PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Rev. 7.1 — 29 June 2015
Product data sheet
1. General description
The PCA9952 and PCA9955 are I2C-bus controlled 16-channel constant current LED
driver optimized for dimming and blinking 57 mA Red/Green/Blue/Amber (RGBA) LEDs in
amusement products. Each LEDn output has its own 8-bit resolution (256 steps) fixed
frequency individual PWM controller that operates at 31.25 kHz with a duty cycle that is
adjustable from 0 % to 99.6 % to allow the LED to be set to a specific brightness value. An
additional 8-bit resolution (256 steps) group PWM controller has both a fixed frequency of
122 Hz and an adjustable frequency between 15 Hz to once every 16.8 seconds with a
duty cycle that is adjustable from 0 % to 99.6 % that is used to either dim or blink all LEDs
with the same value.
Each LEDn output can be off, on (no PWM control), set at its individual PWM controller
value or at both individual and group PWM controller values. The PCA9952 and PCA9955
operate with a supply voltage range of 3 V to 5.5 V and the constant current sink LEDn
outputs allow up to 40 V for the LED supply. The output peak current is adjustable with an
8-bit linear DAC from 225 A to 57 mA.
These devices have built-in open, short load and overtemperature detection circuitry. The
error information from the corresponding register can be read via the I2C-bus. Additionally,
a thermal shutdown feature protects the device when internal junction temperature
exceeds the limit allowed for the process.
The PCA9952 and PCA9955 devices have Fast-mode Plus (Fm+) I2C-bus interface. Fm+
devices offer higher frequency (up to 1 MHz) or more densely populated bus operation
(up to 4000 pF).
The PCA9952 is identical to PCA9955 except for the following differences:
The PCA9952 has only three hardware address pins compared to four on PCA9955.
The PCA9952 has an output enable pin (OE) and the PCA9955 does not.
The active LOW output enable input pin (OE), available only on PCA9952, blinks all the
LEDn outputs and can be used to externally PWM the outputs, which is useful when
multiple devices need to be dimmed or blinked together without using software control.
Software programmable LED Group and three Sub Call I2C-bus addresses allow all or
defined groups of PCA9952/55 devices to respond to a common I2C-bus address,
allowing for example, all red LEDs to be turned on or off at the same time or marquee
chasing effect, thus minimizing I2C-bus commands. On power-up, PCA9952/55 will have
a unique Sub Call address to identify it as a 16-channel LED driver. This allows mixing of
devices with different channel widths. Four hardware address pins on PCA9955 allow up
to 16 devices on the same bus. In the case of PCA9952, three hardware address pins
allow up to 8 devices on the same bus.


PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
The Software Reset (SWRST) function allows the master to perform a reset of the
PCA9952/55 through the I2C-bus, identical to the Power-On Reset (POR) that initializes
the registers to their default state causing the output current switches to be OFF (LED off).
This allows an easy and quick way to reconfigure all device registers to the same
condition.
2. Features and benefits
16 LED drivers. Each output programmable at:
Off
On
Programmable LED brightness
Programmable group dimming/blinking mixed with individual LED brightness
Programmable LEDn output enable delay to reduce EMI and surge currents
16 constant current output channels can sink up to 57 mA, tolerate up to 40 V when
OFF
Output current adjusted through an external resistor
Output current accuracy
6 % between output channels
8 % between PCA9952/55 devices
Open/short load/overtemperature detection mode to detect individual LED errors
1 MHz Fast-mode Plus compatible I2C-bus interface with 30 mA high drive capability
on SDA output for driving high capacitive buses
256-step (8-bit) linear programmable brightness per LEDn output varying from fully off
(default) to maximum brightness using a 31.25 kHz PWM signal
256-step group brightness control allows general dimming (using a 122 Hz PWM
signal) from fully off to maximum brightness (default)
256-step group blinking with frequency programmable from 15 Hz to 16.8 s and duty
cycle from 0 % to 99.6 %
Output state change programmable on the Acknowledge or the STOP Command to
update outputs byte-by-byte or all at the same time (default to ‘Change on STOP’).
Active LOW Output Enable (OE) input pin (only on PCA9952) allows for hardware
blinking and dimming of the LEDs
Four hardware address pins allow 16 PCA9955 devices to be connected to the same
I2C-bus and to be individually programmed
Four software programmable I2C-bus addresses (one LED Group Call address and
three LED Sub Call addresses) allow groups of devices to be addressed at the same
time in any combination (for example, one register used for ‘All Call’ so that all the
PCA9952/55s on the I2C-bus can be addressed at the same time and the second
register used for three different addresses so that 13 of all devices on the bus can be
addressed at the same time in a group). Software enable and disable for each
programmable I2C-bus address.
Unique power-up default Sub Call address allows mixing of devices with different
channel widths
Software Reset feature (SWRST Call) allows the device to be reset through the
I2C-bus
8 MHz internal oscillator requires no external components
PCA9952_PCA9955
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
2 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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NXP Semiconductors
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Internal power-on reset
Noise filter on SDA/SCL inputs
No glitch on LED on power-up
Low standby current
Operating power supply voltage (VDD) range of 3 V to 5.5 V
5.5 V tolerant inputs on non-LED pins
Operating temperature:
20 C to +85 C (PCA9952TW, PCA9955TW)
40 C to +85 C (PCA9952TW/Q900, PCA9955TW/Q900)
ESD protection exceeds 2000 V HBM per JESD22-A114, 750 V CDM (PCA9952TW,
PCA9955TW), and 500 V CDM (PCA9952TW/Q900, PCA9955TW/Q900) per
JESD22-C101
Latch-up testing is done to JEDEC Standard JESD78 Class II, Level B
Packages offered: HTSSOP28
3. Applications
Amusement products
RGB or RGBA LED drivers
LED status information
LED displays
LCD backlights
Keypad backlights for cellular phones or handheld devices
Automotive lighting (PCA9952TW/Q900, PCA9955TW/Q900)
PCA9952_PCA9955
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
3 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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NXP Semiconductors
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
4. Ordering information
Table 1. Ordering information
Type number
Topside Package
marking Name
Description
Version
PCA9952TW
PCA9952 HTSSOP28 plastic thermal enhanced thin shrink small outline package; SOT1172-2
28 leads; body width 4.4 mm; lead pitch 0.65 mm;
exposed die pad
PCA9952TW/Q900[1] PCA9952 HTSSOP28 plastic thermal enhanced thin shrink small outline package; SOT1172-2
28 leads; body width 4.4 mm; lead pitch 0.65 mm;
exposed die pad
PCA9955TW
PCA9955 HTSSOP28 plastic thermal enhanced thin shrink small outline package; SOT1172-2
28 leads; body width 4.4 mm; lead pitch 0.65 mm;
exposed die pad
PCA9955TW/Q900[1] PCA9955 HTSSOP28 plastic thermal enhanced thin shrink small outline package; SOT1172-2
28 leads; body width 4.4 mm; lead pitch 0.65 mm;
exposed die pad
[1] PCA9952TW/Q900 and PCA9955TW/Q900 are AEC-Q100 compliant.
4.1 Ordering options
Table 2. Ordering options
Type number
Orderable
part number
Package Packing method
PCA9952TW
PCA9952TW,118
HTSSOP28 Reel 13” Q1/T1
*standard mark SMD
PCA9952TW/Q900 PCA9952TW/Q900,118 HTSSOP28 Reel 13” Q1/T1
*standard mark SMD
PCA9955TW
PCA9955TW,118
HTSSOP28 Reel 13” Q1/T1
*standard mark SMD
PCA9955TW/Q900 PCA9955TW/Q900,118 HTSSOP28 Reel 13” Q1/T1
*standard mark SMD
Minimum
order
quantity
2500
2500
2500
2500
Temperature
Tamb = 20 C to +85 C
Tamb = 40 C to +85 C
Tamb = 20 C to +85 C
Tamb = 40 C to +85 C
PCA9952_PCA9955
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
4 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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5. Block diagram
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
PCA9952/55
A0 A1 A2 A3/OE(1) REXT
I/O
REGULATOR
LED0
LED1
LED14
LED15
SCL
SDA
VDD
VSS
RESET
DAC0
INPUT FILTER
POWER-ON
RESET
200 kΩ
I2C-BUS
CONTROL
individual LED
current setting
8-bit DACs
DAC1
DAC
14
DAC
15
OUTPUT DRIVER, DELAY CONTROL
AND ERROR DETECTION
INPUT
FILTER
PWM
REGISTER X
BRIGHTNESS
CONTROL
repetion rate 31.25 kHz
LED STATE
SELECT
REGISTER
÷ 256
31.25 kHz
8 MHz
OSCILLATOR
GRPFREQ
REGISTER
DIM CLOCK
GRPPWM
REGISTER
(DUTY CYCLE
CONTROL)
'0' – permanently OFF
'1' – permanently ON
MUX/
CONTROL
Dim repetition rate = 122 Hz.
Blink repetition rate = 15 Hz to every 16.8 seconds.
(1) On PCA9955 this pin is address pin A3. On PCA9952 this pin is OE.
Fig 1. Block diagram of PCA9952/55
002aae909
PCA9952_PCA9955
Product data sheet
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Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
5 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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NXP Semiconductors
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
6. Pinning information
6.1 Pinning
PCA9952TW
PCA9952TW/Q900
REXT 1
A0 2
A1 3
A2 4
OE 5
LED0 6
LED1 7
LED2 8
LED3 9
VSS 10
LED4 11
LED5 12
LED6 13
LED7 14
(1)
28 VDD
27 SDA
26 SCL
25 RESET
24 VSS
23 LED15
22 LED14
21 LED13
20 LED12
19 VSS
18 LED11
17 LED10
16 LED9
15 LED8
002aae911
a. PCA9952TW; PCA9952TW/Q900
(1) Thermal pad; connected to VSS.
Fig 2. Pin configuration for HTSSOP28
PCA9955TW
PCA9955TW/Q900
REXT 1
A0 2
A1 3
A2 4
A3 5
LED0 6
LED1 7
LED2 8
LED3 9
VSS 10
LED4 11
LED5 12
LED6 13
LED7 14
(1)
28 VDD
27 SDA
26 SCL
25 RESET
24 VSS
23 LED15
22 LED14
21 LED13
20 LED12
19 VSS
18 LED11
17 LED10
16 LED9
15 LED8
002aae912
b. PCA9955TW; PCA9955TW/Q900
PCA9952_PCA9955
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
6 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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NXP Semiconductors
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
6.2 Pin description
Table 3.
Symbol
REXT
A0
A1
A2
OE
LED0
LED1
LED2
LED3
LED4
LED5
LED6
LED7
LED8
LED9
LED10
LED11
LED12
LED13
LED14
LED15
RESET
SCL
SDA
VSS
VDD
PCA9952 pin description
Pin Type
1I
2I
3I
4I
5I
6O
7O
8O
9O
11 O
12 O
13 O
14 O
15 O
16 O
17 O
18 O
20 O
21 O
22 O
23 O
25 I
26 I
27 I/O
10, 19, 24[2] ground
28 power supply
Description
current set resistor input; resistor to ground
address input 0[1]
address input 1[1]
address input 2[1]
active LOW output enable
LED driver 0
LED driver 1
LED driver 2
LED driver 3
LED driver 4
LED driver 5
LED driver 6
LED driver 7
LED driver 8
LED driver 9
LED driver 10
LED driver 11
LED driver 12
LED driver 13
LED driver 14
LED driver 15
active LOW reset input
serial clock line
serial data line
supply ground
supply voltage
[1] In order to obtain the best system level ESD performance, a standard pull-up resistor (10 ktypical) is
required for any address pin connecting to VDD. For additional information on system level ESD
performance, please refer to application notes AN10897 and AN11131.
[2] HTSSOP28 package supply ground is connected to both VSS pins and exposed center pad. VSS pins must
be connected to supply ground for proper device operation. For enhanced thermal, electrical, and board
level performance, the exposed pad needs to be soldered to the board using a corresponding thermal pad
on the board and for proper heat conduction through the board, thermal vias need to be incorporated in the
PCB in the thermal pad region.
PCA9952_PCA9955
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
7 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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NXP Semiconductors
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Table 4.
Symbol
REXT
A0
A1
A2
A3
LED0
LED1
LED2
LED3
LED4
LED5
LED6
LED7
LED8
LED9
LED10
LED11
LED12
LED13
LED14
LED15
RESET
SCL
SDA
VSS
VDD
PCA9955 pin description
Pin Type
1I
2I
3I
4I
5I
6O
7O
8O
9O
11 O
12 O
13 O
14 O
15 O
16 O
17 O
18 O
20 O
21 O
22 O
23 O
25 I
26 I
27 I/O
10, 19, 24[2] ground
28 power supply
Description
current set resistor input; resistor to ground
address input 0[1]
address input 1[1]
address input 2[1]
address input 3[1]
LED driver 0
LED driver 1
LED driver 2
LED driver 3
LED driver 4
LED driver 5
LED driver 6
LED driver 7
LED driver 8
LED driver 9
LED driver 10
LED driver 11
LED driver 12
LED driver 13
LED driver 14
LED driver 15
active LOW reset input
serial clock line
serial data line
supply ground
supply voltage
[1] In order to obtain the best system level ESD performance, a standard pull-up resistor (10 ktypical) is
required for any address pin connecting to VDD. For additional information on system level ESD
performance, please refer to application notes AN10897 and AN11131.
[2] HTSSOP28 package supply ground is connected to both VSS pins and exposed center pad. VSS pins must
be connected to supply ground for proper device operation. For enhanced thermal, electrical, and board
level performance, the exposed pad needs to be soldered to the board using a corresponding thermal pad
on the board and for proper heat conduction through the board, thermal vias need to be incorporated in the
PCB in the thermal pad region.
PCA9952_PCA9955
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
8 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7. Functional description
Refer to Figure 1 “Block diagram of PCA9952/55”.
7.1 Device addresses
Following a START condition, the bus master must output the address of the slave it is
accessing.
For PCA9955 there are a maximum of 16 possible programmable addresses using the
4 hardware address pins.
For PCA9952 there are a maximum of 8 possible programmable addresses using the
3 hardware address pins.
7.1.1 Regular I2C-bus slave address
The I2C-bus slave address of the PCA9955 is shown in Figure 3. To conserve power, no
internal pull-up resistors are incorporated on the hardware selectable address pins and
they must be pulled HIGH or LOW externally. Figure 4 shows the I2C-bus slave address of
the PCA9952.
Remark: Reserved I2C-bus addresses must be used with caution since they can interfere
with:
‘reserved for future use’ I2C-bus addresses (0000 011, 1111 1XX)
slave devices that use the 10-bit addressing scheme (1111 0XX)
slave devices that are designed to respond to the General Call address (0000 000)
High-speed mode (Hs-mode) master code (0000 1XX)
slave address
slave address
1 1 0 A3 A2 A1 A0 R/W
1 1 0 0 A2 A1 A0 R/W
fixed
hardware
selectable
002aae914
fixed
hardware
selectable
002aae915
Fig 3. PCA9955 slave address
Fig 4. PCA9952 slave address
The last bit of the address byte defines the operation to be performed. When set to logic 1
a read is selected, while a logic 0 selects a write operation.
7.1.2 LED All Call I2C-bus address
Default power-up value (ALLCALLADR register): E0h or 1110 000X
Programmable through I2C-bus (volatile programming)
At power-up, LED All Call I2C-bus address is enabled. PCA9952/55 sends an ACK
when E0h (R/W = 0) or E1h (R/W = 1) is sent by the master.
See Section 7.3.10 “ALLCALLADR, LED All Call I2C-bus address” for more detail.
PCA9952_PCA9955
Product data sheet
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Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
9 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Remark: The default LED All Call I2C-bus address (E0h or 1110 000X) must not be used
as a regular I2C-bus slave address since this address is enabled at power-up. All of the
PCA9952/55s on the I2C-bus will acknowledge the address if sent by the I2C-bus master.
7.1.3 LED bit Sub Call I2C-bus addresses
3 different I2C-bus addresses can be used
Default power-up values:
SUBADR1 register: ECh or 1110 110X
SUBADR2 register: ECh or 1110 110X
SUBADR3 register: ECh or 1110 110X
Programmable through I2C-bus (volatile programming)
At power-up, SUBADR1 is enabled while SUBADR2 and SUBADR3 I2C-bus
addresses are disabled.
Remark: At power-up SUBADR1 identifies this device as a 16-channel driver.
See Section 7.3.9 “LED bit Sub Call I2C-bus addresses for PCA9952/55” for more detail.
Remark: The default LED Sub Call I2C-bus addresses may be used as regular I2C-bus
slave addresses as long as they are disabled.
7.2 Control register
Following the successful acknowledgement of the slave address, LED All Call address or
LED Sub Call address, the bus master will send a byte to the PCA9952/55, which will be
stored in the Control register.
The lowest 7 bits are used as a pointer to determine which register will be accessed
(D[6:0]). The highest bit is used as Auto-Increment Flag (AIF). The AIF is active by default
at power-up.
This bit along with the MODE1 register bit 5 and bit 6 provide the Auto-Increment feature.
register address
AIF D6 D5 D4 D3 D2 D1 D0
Auto-Increment Flag
002aad850
Fig 5.
reset state = 80h
Remark: The Control register does not apply to the Software Reset I2C-bus address.
Control register
When the Auto-Increment Flag is set (AIF = logic 1), the seven low-order bits of the
Control register are automatically incremented after a read or write. This allows the user to
program the registers sequentially. Four different types of Auto-Increment are possible,
depending on AI1 and AI0 values of MODE1 register.
PCA9952_PCA9955
Product data sheet
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Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Table 5. Auto-Increment options
AIF AI1[1] AI0[1] Function
0 0 0 no Auto-Increment
1 0 0 Auto-Increment for registers (00h to 41h). D[6:0] roll over to 00h after the last
register 41h is accessed.
1 0 1 Auto-Increment for individual brightness registers only (0Ah to 19h). D[6:0] roll
over to 0Ah after the last register (19h) is accessed.
1 1 0 Auto-Increment for MODE1 to IREF15 control registers (00h to 31h).
D[6:0] roll over to 00h after the last register (31h) is accessed.
1 1 1 Auto-Increment for global control registers and individual brightness registers
(08h to 19h). D[6:0] roll over to 08h after the last register (19h) is accessed.
[1] AI1 and AI0 come from MODE1 register.
Remark: Other combinations not shown in Table 5 (AIF + AI[1:0] = 001b, 010b and 011b)
are reserved and must not be used for proper device operation.
AIF + AI[1:0] = 000b is used when the same register must be accessed several times
during a single I2C-bus communication, for example, changes the brightness of a single
LED. Data is overwritten each time the register is accessed during a write operation.
AIF + AI[1:0] = 100b is used when all the registers must be sequentially accessed, for
example, power-up programming.
AIF + AI[1:0] = 101b is used when the 16 LED drivers must be individually programmed
with different values during the same I2C-bus communication, for example, changing color
setting to another color setting.
AIF + AI[1:0] = 110b is used when MODE1 to IREF15 registers must be programmed with
different settings during the same I2C-bus communication.
AIF + AI[1:0] = 111b is used when the 16 LED drivers must be individually programmed
with different values in addition to global programming.
Only the 7 least significant bits D[6:0] are affected by the AIF, AI1 and AI0 bits.
When the Control register is written, the register entry point determined by D[6:0] is the
first register that will be addressed (read or write operation), and can be anywhere
between 00h and 41h (as defined in Table 6). When AIF = 1, the Auto-Increment Flag is
set and the rollover value at which the register increment stops and goes to the next one
is determined by AIF, AI1 and AI0. See Table 5 for rollover values. For example, if MODE1
register bit AI1 = 0 and AI0 = 1 and if the Control register = 1001 0000, then the register
addressing sequence will be (in hexadecimal):
10 11 19 0A 0B 19 0A 0B … as long as the master
keeps sending or reading data.
If MODE1 register bit AI1 = 0 and AI0 = 0 and if the Control register = 1010 0010, then the
register addressing sequence will be (in hexadecimal):
22 23 41 00 01 19 0A 0B … as long as the master
keeps sending or reading data.
PCA9952_PCA9955
Product data sheet
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Rev. 7.1 — 29 June 2015
© NXP Semiconductors N.V. 2015. All rights reserved.
11 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
If MODE1 register bit AI1 = 0 and AI0 = 1 and if the Control register = 1000 0101, then the
register addressing sequence will be (in hexadecimal):
05 06 19 0A 0B 19 0A 0B … as long as the master
keeps sending or reading data.
Remark: Writing to registers marked ‘not used’ will return NACK.
7.3 Register definitions
Table 6. Register summary[1]
Register
D6 D5 D4 D3 D2 D1 D0 Name
number
(hexadecimal)
00h 0 0 0 0 0 0 0 MODE1
01h 0 0 0 0 0 0 1 MODE2
02h 0 0 0 0 0 1 0 LEDOUT0
03h 0 0 0 0 0 1 1 LEDOUT1
04h 0 0 0 0 1 0 0 LEDOUT2
05h 0 0 0 0 1 0 1 LEDOUT3
06h 0 0 0 0 1 1 0 -
07h 0 0 0 0 1 1 1 -
08h 0 0 0 1 0 0 0 GRPPWM
09h 0 0 0 1 0 0 1 GRPFREQ
0Ah 0 0 0 1 0 1 0 PWM0
0Bh 0 0 0 1 0 1 1 PWM1
0Ch 0 0 0 1 1 0 0 PWM2
0Dh 0 0 0 1 1 0 1 PWM3
0Eh 0 0 0 1 1 1 0 PWM4
0Fh 0 0 0 1 1 1 1 PWM5
10h 0 0 1 0 0 0 0 PWM6
11h 0 0 1 0 0 0 1 PWM7
12h 0 0 1 0 0 1 0 PWM8
13h 0 0 1 0 0 1 1 PWM9
14h 0 0 1 0 1 0 0 PWM10
15h 0 0 1 0 1 0 1 PWM11
16h 0 0 1 0 1 1 0 PWM12
17h 0 0 1 0 1 1 1 PWM13
18h 0 0 1 1 0 0 0 PWM14
19h 0 0 1 1 0 0 1 PWM15
1Ah to 21h
--------
22h 0 1 0 0 0 1 0 IREF0
23h 0 1 0 0 0 1 1 IREF1
24h 0 1 0 0 1 0 0 IREF2
25h 0 1 0 0 1 0 1 IREF3
26h 0 1 0 0 1 1 0 IREF4
Type
Function
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
Mode register 1
Mode register 2
LEDn output state 0
LEDn output state 1
LEDn output state 2
LEDn output state 3
not used[1]
not used[1]
group duty cycle control
group frequency
brightness control LED0
brightness control LED1
brightness control LED2
brightness control LED3
brightness control LED4
brightness control LED5
brightness control LED6
brightness control LED7
brightness control LED8
brightness control LED9
brightness control LED10
brightness control LED11
brightness control LED12
brightness control LED13
brightness control LED14
brightness control LED15
not used[1]
output gain control register 0
output gain control register 1
output gain control register 2
output gain control register 3
output gain control register 4
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Table 6. Register summary[1] …continued
Register
D6 D5 D4 D3 D2 D1 D0 Name
number
(hexadecimal)
27h 0 1 0 0 1 1 1 IREF5
28h 0 1 0 1 0 0 0 IREF6
29h 0 1 0 1 0 0 1 IREF7
2Ah 0 1 0 1 0 1 0 IREF8
2Bh 0 1 0 1 0 1 1 IREF9
2Ch 0 1 0 1 1 0 0 IREF10
2Dh 0 1 0 1 1 0 1 IREF11
2Eh 0 1 0 1 1 1 0 IREF12
2Fh 0 1 0 1 1 1 1 IREF13
30h 0 1 1 0 0 0 0 IREF14
31h 0 1 1 0 0 0 1 IREF15
32h to 39h
--------
3Ah 0 1 1 1 0 1 0 OFFSET
3Bh 0 1 1 1 0 1 1 SUBADR1
3Ch 0 1 1 1 1 0 0 SUBADR2
3Dh 0 1 1 1 1 0 1 SUBADR3
3Eh 0 1 1 1 1 1 0 ALLCALLADR
3Fh 0 1 1 1 1 1 1 RESERVED1
40h 1 0 0 0 0 0 0 RESERVED2
41h 1 0 0 0 0 0 1 RESERVED3
42h 1 0 0 0 0 1 0 PWMALL
43h 1 0 0 0 0 1 1 IREFALL
Type
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read/write
read only
read only
write only
write only
44h
45h
46h to 7Fh
1 0 0 0 1 0 0 EFLAG0
1 0 0 0 1 0 1 EFLAG1
--------
read only
read only
read only
Function
output gain control register 5
output gain control register 6
output gain control register 7
output gain control register 8
output gain control register 9
output gain control register 10
output gain control register 11
output gain control register 12
output gain control register 13
output gain control register 14
output gain control register 15
not used[1]
Offset/delay on LEDn outputs
I2C-bus subaddress 1
I2C-bus subaddress 2
I2C-bus subaddress 3
All Call I2C-bus address
reserved[2]
reserved[2]
reserved[2]
brightness control for all LEDn
output gain control for all registers
IREF0 to IREF15
output error flag 0
output error flag 1
not used[1]
[1] Remark: Writing to registers marked ‘not used’ will return a NACK.
[2] Remark: Writing to registers marked ‘reserved’ will not change any functionality in the chip.
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7.3.1 MODE1 — Mode register 1
Table 7. MODE1 - Mode register 1 (address 00h) bit description
Legend: * default value.
Bit Symbol
Access
Value Description
7 AIF
read only
0
Register Auto-Increment disabled.
1* Register Auto-Increment enabled.
6 AI1
R/W 0* Auto-Increment bit 1 = 0. Auto-increment range as defined in Table 5.
1 Auto-Increment bit 1 = 1. Auto-increment range as defined in Table 5.
5 AI0
R/W 0* Auto-Increment bit 0 = 0. Auto-increment range as defined in Table 5.
1 Auto-Increment bit 0 = 1. Auto-increment range as defined in Table 5.
4 SLEEP R/W
0* Normal mode[1].
1 Low-power mode. Oscillator off[2][3].
3 SUB1
R/W
0 PCA9952; PCA9955 does not respond to I2C-bus subaddress 1.
1* PCA9952; PCA9955 responds to I2C-bus subaddress 1.
2 SUB2
R/W
0* PCA9952; PCA9955 does not respond to I2C-bus subaddress 2.
1 PCA9952; PCA9955 responds to I2C-bus subaddress 2.
1 SUB3
R/W
0* PCA9952; PCA9955 does not respond to I2C-bus subaddress 3.
1 PCA9952; PCA9955 responds to I2C-bus subaddress 3.
0
ALLCALL
R/W
0 PCA9952; PCA9955 does not respond to LED All Call I2C-bus address.
1* PCA9952; PCA9955 responds to LED All Call I2C-bus address.
[1] It takes 500 s max. for the oscillator to be up and running once SLEEP bit has been set to logic 0. Timings on LEDn outputs are not
guaranteed if PWMx, GRPPWM or GRPFREQ registers are accessed within the 500 s window.
[2] No blinking or dimming is possible when the oscillator is off.
[3] The device must be reset if the LED driver output state is set to LDRx=11 after the device is set back to Normal mode.
7.3.2 MODE2 — Mode register 2
Table 8. MODE2 - Mode register 2 (address 01h) bit description
Legend: * default value.
Bit Symbol
Access
Value Description
7 OVERTEMP read only 0*
O.K.
1 overtemperature condition
6 FAULTTEST R/W
0* LED fault test complete
1 start fault test
5
DMBLNK
R/W
0* group control = dimming.
1 group control = blinking.
4-
read only 0*
reserved
3 OCH
R/W 0* outputs change on STOP command
1 outputs change on ACK
2-
read only 1*
reserved
1-
read only 0*
reserved
0-
read only 1*
reserved
PCA9952_PCA9955
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14 of 48


PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7.3.3 LEDOUT0 to LEDOUT3, LED driver output state
Table 9. LEDOUT0 to LEDOUT3 - LED driver output state registers (address 02h to 05h)
bit description
Legend: * default value.
Address Register Bit Symbol Access Value
Description
02h LEDOUT0 7:6 LDR3 R/W 00*
LED3 output state control
5:4 LDR2
R/W 00*
LED2 output state control
3:2 LDR1
R/W 00*
LED1 output state control
1:0 LDR0
R/W 00*
LED0 output state control
03h LEDOUT1 7:6 LDR7 R/W 00*
LED7 output state control
5:4 LDR6
R/W 00*
LED6 output state control
3:2 LDR5
R/W 00*
LED5 output state control
1:0 LDR4
R/W 00*
LED4 output state control
04h
LEDOUT2 7:6 LDR11
R/W 00*
LED11 output state control
5:4 LDR10
R/W 00*
LED10 output state control
3:2 LDR9
R/W 00*
LED9 output state control
1:0 LDR8
R/W 00*
LED8 output state control
05h
LEDOUT3 7:6 LDR15
R/W 00*
LED15 output state control
5:4 LDR14
R/W 00*
LED14 output state control
3:2 LDR13
R/W 00*
LED13 output state control
1:0 LDR12
R/W 00*
LED12 output state control
LDRx = 00 — LED driver x is off (default power-up state).
LDRx = 01 — LED driver x is fully on (individual brightness and group dimming/blinking
not controlled).
LDRx = 10 — LED driver x individual brightness can be controlled through its PWMx
register.
LDRx = 11 — LED driver x individual brightness and group dimming/blinking can be
controlled through its PWMx register and the GRPPWM registers.
Remark: Setting the device in low power mode while being on group dimming/blinking
mode may cause the LED output state to be in an unknown state after the device is set
back to normal mode. The device must be reset and all register values reprogrammed.
7.3.4 GRPPWM, group duty cycle control
Table 10. GRPPWM - Group brightness control register (address 08h) bit description
Legend: * default value
Address Register Bit Symbol Access Value
Description
08h
GRPPWM 7:0 GDC[7:0] R/W
1111 1111* GRPPWM register
When DMBLNK bit (MODE2 register) is programmed with logic 0, a 122 Hz fixed
frequency signal is superimposed with the 31.25 kHz individual brightness control signal.
GRPPWM is then used as a global brightness control allowing the LEDn outputs to be
dimmed with the same value. The value in GRPFREQ is then a ‘Don’t care’.
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
General brightness for the 16 outputs is controlled through 256 linear steps from 00h
(0 % duty cycle = LEDn output off) to FFh (99.6 % duty cycle = maximum brightness).
Applicable to LEDn outputs programmed with LDRx = 11 (LEDOUT0 to LEDOUT3
registers).
When DMBLNK bit is programmed with logic 1, GRPPWM and GRPFREQ registers
define a global blinking pattern, where GRPFREQ contains the blinking period (from
67 ms to 16.8 s) and GRPPWM the duty cycle (ON/OFF ratio in %).
duty cycle = G-----D-----C-------7---:--0----
256
(1)
7.3.5 GRPFREQ, group frequency
Table 11. GRPFREQ - Group frequency register (address 09h) bit description
Legend: * default value.
Address Register Bit Symbol Access Value
Description
09h
GRPFREQ 7:0 GFRQ[7:0] R/W
0000 0000* GRPFREQ register
GRPFREQ is used to program the global blinking period when DMBLNK bit (MODE2
register) is equal to 1. Value in this register is a ‘Don’t care’ when DMBLNK = 0.
Applicable to LEDn outputs programmed with LDRx = 11 (LEDOUT0 to LEDOUT3
registers).
Blinking period is controlled through 256 linear steps from 00h (67 ms, frequency 15 Hz)
to FFh (16.8 s).
global
blinking
period
=
G-----F----R----Q-------7----:--0-------+-----1-
15.26
s
(2)
7.3.6 PWM0 to PWM15, individual brightness control
Table 12. PWM0 to PWM15 - PWM registers 0 to 15 (address 0Ah to 19h) bit description
Legend: * default value.
Address Register Bit Symbol Access Value
Description
0Ah PWM0 7:0 IDC0[7:0] R/W 0000 0000* PWM0 Individual Duty Cycle
0Bh PWM1 7:0 IDC1[7:0] R/W 0000 0000* PWM1 Individual Duty Cycle
0Ch PWM2 7:0 IDC2[7:0] R/W 0000 0000* PWM2 Individual Duty Cycle
0Dh PWM3 7:0 IDC3[7:0] R/W 0000 0000* PWM3 Individual Duty Cycle
0Eh PWM4 7:0 IDC4[7:0] R/W 0000 0000* PWM4 Individual Duty Cycle
0Fh PWM5 7:0 IDC5[7:0] R/W 0000 0000* PWM5 Individual Duty Cycle
10h PWM6 7:0 IDC6[7:0] R/W 0000 0000* PWM6 Individual Duty Cycle
11h PWM7 7:0 IDC7[7:0] R/W 0000 0000* PWM7 Individual Duty Cycle
12h PWM8 7:0 IDC8[7:0] R/W 0000 0000* PWM8 Individual Duty Cycle
13h PWM9 7:0 IDC9[7:0] R/W 0000 0000* PWM9 Individual Duty Cycle
14h PWM10 7:0 IDC10[7:0] R/W 0000 0000* PWM10 Individual Duty Cycle
15h PWM11 7:0 IDC11[7:0] R/W 0000 0000* PWM11 Individual Duty Cycle
16h PWM12 7:0 IDC12[7:0] R/W 0000 0000* PWM12 Individual Duty Cycle
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Table 12. PWM0 to PWM15 - PWM registers 0 to 15 (address 0Ah to 19h) bit description
…continued
Address Register Bit Symbol Access Value
Description
17h PWM13 7:0 IDC13[7:0] R/W 0000 0000* PWM13 Individual Duty Cycle
18h PWM14 7:0 IDC14[7:0] R/W 0000 0000* PWM14 Individual Duty Cycle
19h PWM15 7:0 IDC15[7:0] R/W 0000 0000* PWM15 Individual Duty Cycle
A 31.25 kHz fixed frequency signal is used for each output. Duty cycle is controlled
through 256 linear steps from 00h (0 % duty cycle = LEDn output off) to FFh
(99.6 % duty cycle = LEDn output at maximum brightness). Applicable to LEDn outputs
programmed with LDRx = 10 or 11 (LEDOUT0 to LEDOUT3 registers).
duty
cycle
=
I---D-----C----x-----7----:--0----
256
(3)
Remark: The first lower end 8 steps of PWM and the last (higher end) steps of PWM will
not have effective brightness control of LEDs due to edge rate control of LEDn output
pins.
7.3.7 IREF0 to IREF15, LEDn output current value registers
These registers reflect the gain settings for output current for LED0 to LED15.
Table 13. IREF0 to IREF15 - LEDn output gain control registers (address 22h to 31h)
bit description
Legend: * default value.
Address Register Bit Access Value Description
22h
IREF0
7:0 R/W
00h* LED0 output current setting
23h
IREF1
7:0 R/W
00h* LED1 output current setting
24h
IREF2
7:0 R/W
00h* LED2 output current setting
25h
IREF3
7:0 R/W
00h* LED3 output current setting
26h
IREF4
7:0 R/W
00h* LED4 output current setting
27h
IREF5
7:0 R/W
00h* LED5 output current setting
28h
IREF6
7:0 R/W
00h* LED6 output current setting
29h
IREF7
7:0 R/W
00h* LED7 output current setting
2Ah
IREF8
7:0 R/W
00h* LED8 output current setting
2Bh
IREF9
7:0 R/W
00h* LED9 output current setting
2Ch
IREF10 7:0 R/W
00h* LED10 output current setting
2Dh
IREF11 7:0 R/W
00h* LED11 output current setting
2Eh
IREF12 7:0 R/W
00h* LED12 output current setting
2Fh
IREF13 7:0 R/W
00h* LED13 output current setting
30h
IREF14 7:0 R/W
00h* LED14 output current setting
31h
IREF15 7:0 R/W
00h* LED15 output current setting
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7.3.8 OFFSET — LEDn output delay offset register
Table 14. OFFSET - LEDn output delay offset register (address 3Ah) bit description
Legend: * default value.
Address Register Bit Access Value Description
3Ah OFFSET 7:4 read only 0000* not used
3:0 R/W
1000* LEDn output delay offset factor
The OFFSET register should not be changed while the LEDn output is on and pulsing.
The PCA9955 can be programmed to have turn-on delay between LEDn outputs. This
helps to reduce peak current for the VDD supply and reduces EMI.
The order in which the LEDn outputs are enabled will always be the same (channel 0 will
enable first and channel 15 will enable last).
OFFSET control register bits [3:0] determine the delay used between the turn-on times as
follows:
0000 = no delay between outputs (all on, all off at the same time)
0001 = delay of 1 clock cycle (125 ns) between successive outputs
0010 = delay of 2 clock cycles (250 ns) between successive outputs
0011 = delay of 3 clock cycles (375 ns) between successive outputs
:
1111 = delay of 15 clock cycles (1.875 s) between successive outputs
Example: If the value in the OFFSET register is 1000 the corresponding delay =
8 125 ns = 1 s delay between successive outputs.
channel 0 turns on at time 0 s
channel 1 turns on at time 1 s
channel 2 turns on at time 2 s
channel 3 turns on at time 3 s
channel 4 turns on at time 4 s
channel 5 turns on at time 5 s
channel 6 turns on at time 6 s
channel 7 turns on at time 7 s
channel 8 turns on at time 8 s
channel 9 turns on at time 9 s
channel 10 turns on at time 10 s
channel 11 turns on at time 11 s
channel 12 turns on at time 12 s
channel 13 turns on at time 13 s
channel 14 turns on at time 14 s
channel 15 turns on at time 15 s
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7.3.9 LED bit Sub Call I2C-bus addresses for PCA9952/55
Table 15. SUBADR1 to SUBADR3 - I2C-bus subaddress registers 1 to 3 (address 3Bh to
3Dh) bit description
Legend: * default value.
Address Register
Bit Symbol Access Value
Description
3Bh SUBADR1 7:1 A1[7:1] R/W 1110 110* I2C-bus subaddress 1
0 A1[0]
R only 0*
reserved
3Ch SUBADR2 7:1 A2[7:1] R/W 1110 110* I2C-bus subaddress 2
0 A2[0]
R only 0*
reserved
3Dh SUBADR3 7:1 A3[7:1] R/W 1110 110* I2C-bus subaddress 3
0 A3[0]
R only 0*
reserved
Default power-up values are ECh, ECh, ECh. At power-up, SUBADR1 is enabled while
SUBADR2 and SUBADR3 are disabled. The power-up default bit subaddress of ECh
indicates that this device is a 16-channel LED driver.
All three subaddresses are programmable. Once subaddresses have been programmed
to their right values, SUBx bits need to be set to logic 1 in order to have the device
acknowledging these addresses (MODE1 register) (0). When SUBx is set to logic 1, the
corresponding I2C-bus subaddress can be used during either an I2C-bus read or write
sequence.
7.3.10 ALLCALLADR, LED All Call I2C-bus address
Table 16. ALLCALLADR - LED All Call I2C-bus address register (address 3Eh) bit
description
Legend: * default value.
Address Register
Bit Symbol Access Value
Description
3Eh ALLCALLADR 7:1 AC[7:1] R/W 1110 000* ALLCALL I2C-bus
address register
0 AC[0] R only 0*
reserved
The LED All Call I2C-bus address allows all the PCA9952/55s on the bus to be
programmed at the same time (ALLCALL bit in register MODE1 must be equal to logic 1
(power-up default state)). This address is programmable through the I2C-bus and can be
used during either an I2C-bus read or write sequence. The register address can also be
programmed as a Sub Call.
Only the 7 MSBs representing the All Call I2C-bus address are valid. The LSB in
ALLCALLADR register is a read-only bit (0).
If ALLCALL bit = 0, the device does not acknowledge the address programmed in register
ALLCALLADR.
7.3.11 RESERVED1
This register is reserved.
7.3.12 RESERVED2, RESERVED3
These registers are reserved.
PCA9952_PCA9955
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7.3.13 PWMALL — brightness control for all LEDn outputs
When programmed, the value in this register will be used for PWM duty cycle for all the
LEDn outputs and will be reflected in PWM0 through PWM15 registers.
Write to any of the PWM0 to PWM15 registers will overwrite the value in corresponding
PWMn register programmed by PWMALL.
Table 17. PWMALL - brightness control for all LEDn outputs register (address 42h)
bit description
Legend: * default value.
Address Register Bit Access
Value
Description
42h PWMALL 7:0 write only 0000 0000* duty cycle for all LEDn outputs
7.3.14 IREFALL register: output current value for all LEDn outputs
The output current setting for all outputs is held in this register. When this register is
written to or updated, all LEDn outputs will be set to a current corresponding to this
register value.
Write to IREF0 to IREF15 will overwrite the output current settings.
Table 18. IREFALL - Output gain control for all LEDn outputs (address 43h) bit description
Legend: * default value.
Bit Symbol Access
Value
Description
7:0 IREFALL write only 00h*
Current gain setting for all LEDn outputs.
7.3.15 LED driver constant current outputs
In LED display applications, PCA9952/55 provides nearly no current variations from
channel to channel and from device to device. The maximum current skew between
channels is less than 6 % and less than 8 % between devices.
7.3.15.1 Adjusting output peak current
The PCA9952/55 scales up the reference current (Iref) set by the external resistor (Rext) to
sink the output current (IO) at each output port. The maximum output peak current for the
outputs can be set using Rext. In addition, the constant value for current drive at each of
the outputs is independently programmable using command registers IREF0 to IREF15.
Alternatively, programming the IREFALL register allows all outputs to be set at one current
value determined by the value in IREFALL register.
Equation 4 and Equation 5 can be used to calculate the minimum and maximum constant
current values that can be programmed for the outputs for a chosen Rext.
IO_LED_LSB
=
9---0---0------m----V-- 1--
Rext 4
IO_LED_MAX
=
255 IO_LED_LSB
=
9---0---0------m----V--
Rext
2----54---5-
(4)
(5)
For a given IREFx setting,
IO_LED
=
IREFx 9---0---0------m----V-- 1-- .
Rext 4
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
Example 1: If Rext = 1 k, IO_LED_LSB = 225 A, IO_LED_MAX = 57.375 mA.
So each channel can be programmed with its individual IREFx in 256 steps and in 225 A
increments to a maximum output current of 57.375 mA independently.
Example 2: If Rext = 2 k, IO_LED_LSB = 112.5 A, IO_LED_MAX = 28.687 mA.
So each channel can be programmed with its individual IREFx in 256 steps and in
112.5 A increments to a maximum output channel of 28.687 mA independently.
80
IO(LEDn)
(mA)
60
IREFx = 255
002aag288
40
20
0
1 2 3 4 5 6 7 8 9 10
Rext (kΩ)
Fig 6.
IO(LEDn) (mA) = IREFx (0.9 / 4) / Rext (k)
maximum IO(LEDn) (mA) = 255 (0.9 / 4) / Rext (k)
Remark: Default IREFx at power-up = 0.
Maximum ILED versus Rext
57.375(1)
IO(target)
(mA)
40
30
20
10
0
0
31 63 95
(1) Assuming Rext = 1 k.
Fig 7. IO(target) versus IREFx value
002aaf396
127 159 191 223 255
IREFx[7:0] value
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PCA9955 (NXP)
16-channel constant current LED driver

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PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
7.3.16 LED error detection
The PCA9952/55 is capable of detecting an LED open or a short condition at its LEDn
output. To detect LED error status, user must initiate the LEDn output fault test. The
LEDout channel under test must be ON to conduct this test.
Setting MODE2[6] = 1 initiates the FAULTTEST. The entire test sequence takes up to
52 s. Once the test cycle begins, all outputs will be turned off (no matter where they are
in the group or individual PWM cycle) until entire test sequence is finished and next
register read or write is activated. Then each output will be enabled at its previously
defined output current level based on IREFx for 1.25 s. Only those channels with an
LEDOUT value other than 00h will be tested. If the output is selected to be fully on,
individual dim, or individual and group dim that channel will be tested; however, its
operation will be affected for one entire 32 s individual PWM cycle. At the end of the test
cycle PCA9952/55 writes out the 16 error flag bits to EFLAGn.
Before reading the error flag register EFLAGn, user should verify if the FAULTTEST is
complete by reading MODE2 register. MODE2[6] = 0 indicates that the test is complete
and the error status is ready in EFLAG0 and EFLAG1.
The error flags in registers EFLAG0 and EFLAG1 can now be read.
Table 19. EFLAG0, EFLAG1 - Error flag registers (address 44h, 45h) bit description
Legend: * default value.
Address Register Bit Access Value Description
44h EFLAG0 7:0 R only 00h* Error flag 0; lower 8-bit channel error status
45h EFLAG1 7:0 R only 00h* Error flag 1; upper 8-bit channel error status
Remark: The LED open and short-circuit error status bits share the same error flag
registers (EFLAG0/EFLAG1). If both LED open and short-circuit conditions exist on
different LED outputs, the error status bits in error flag registers report only the
open-circuits first and disregards the short-circuits. If only one of the two conditions (that
is, LED open-circuits or short-circuits) exists, then the error status bits in error flag
registers will report all of those faulted channels. For all unused LED outputs, user must
program their LED outputs to the ‘OFF’ state (LDRx = 00) and IREFx value to 00h, and all
unused LED output pins must be pulled up to VDD with a recommended 100 kshared
resistor. The states of the unused LED channels have no effect upon the FAULTTEST and
always return 0s in EFLAG0/EFLAG1 registers.
7.3.16.1 Open-circuit detection principle
The PCA9952/55 LED open-circuit detection compares the effective current level IO with
the open load detection threshold current Ith(det). If IO is below the threshold Ith(det), the
PCA9952/55 detects an open load condition. This error status can be read out as an
error flag through the registers EFLAG0 and EFLAG1. For open-circuit error detection of
an output channel, that channel must be ON.
Table 20. Open-circuit detection
State of
output port
Condition of
output current
OFF
ON
IO = 0 mA
IO < Ith(det)[1]
IO Ith(det)[1]
Error status code
Description
0
1
channel n error status bit 0
detection not possible
open-circuit
normal
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16-channel Fm+ I2C-bus 57 mA constant current LED driver
[1] Ith(det) = 0.5 IO(target) (typical). This threshold may be different for each I/O and only depends on IREFx and
Rext.
7.3.16.2 Short-circuit detection principle
The LED short-circuit detection compares the effective voltage level (VO) with the
shorted-load detection threshold voltages Vth(trig). If VO is above the Vth(trig) threshold, the
PCA9952/55 detects a shorted-load condition. If VO is below the Vth(trig) threshold, no error
is detected or error bit is reset. This error status can be read out as an error flag through
the registers EFLAG0 and EFLAG1. For short-circuit error detection, a channel must be
on.
Table 21. Shorted-load detection
State of
output port
Condition of
output voltage
OFF -
ON VO Vth(trig)[1]
VO < Vth(trig)[1]
Error status code
Description
0
1
channel n error status bit 0
detection not possible
short-circuit
normal
[1] Vth 2.5 V.
Remark: The error status does not distinguish between an LED short condition and an
LED open condition. When an LED fault condition is noted, the LEDn outputs should be
turned off to prevent heat dissipation in the chip and the repair should be done.
7.3.17 Overtemperature protection
If the PCA9952/55 chip temperature exceeds its limit (Tth(otp), see Table 24), all output
channels will be disabled until the temperature drops below its limit minus a small
hysteresis (Thys, see Table 24). When an overtemperature situation is encountered, the
OVERTEMP flag (bit 7) is set in the MODE2 register. Once the die temperature reduces
below the Tth(otp) Thys, the chip will return to the same condition it was prior to the
overtemperature event and the OVERTEMP flag will be cleared.
7.4 Active LOW output enable input
Remark: Only the PCA9952 has the OE pin.
The active LOW output enable (OE) pin on PCA9952 allows to enable or disable all the
LEDn outputs at the same time.
When a LOW level is applied to OE pin, all the LEDn outputs are enabled.
When a HIGH level is applied to OE pin, all the LEDn outputs are high-impedance.
The OE pin can be used as a synchronization signal to switch on/off several PCA9952
devices at the same time. This requires an external clock reference that provides blinking
period and the duty cycle.
The OE pin can also be used as an external dimming control signal. The frequency of the
external clock must be high enough not to be seen by the human eye, and the duty cycle
value determines the brightness of the LEDs.
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Remark: Do not use OE as an external blinking control signal when internal global
blinking is selected (DMBLNK = 1, MODE2 register) since it will result in an undefined
blinking pattern. Do not use OE as an external dimming control signal when internal global
dimming is selected (DMBLNK = 0, MODE2 register) since it will result in an undefined
dimming pattern.
7.5 Power-on reset
When power is applied to VDD, an internal power-on reset holds the PCA9952/55 in a
reset condition until VDD has reached VPOR. At this point, the reset condition is released
and the PCA9952/55 registers and I2C-bus state machine are initialized to their default
states (all zeroes) causing all the channels to be deselected. Thereafter, VDD must be
pulled lower than 1 V and stay LOW for longer than 20 s. The device will reset itself, and
allow 2 ms for the device to fully wake up.
7.6 Hardware reset recovery
When a reset of PCA9952/55 is activated using an active LOW input on the RESET pin, a
reset pulse width of 2.5 s minimum is required. The maximum wait time after RESET pin
is released is 1.5 ms.
7.7 Software reset
The Software Reset Call (SWRST Call) allows all the devices in the I2C-bus to be reset to
the power-up state value through a specific formatted I2C-bus command. To be performed
correctly, it implies that the I2C-bus is functional and that there is no device hanging the
bus.
The maximum wait time after software reset is 1 ms.
The SWRST Call function is defined as the following:
1. A START command is sent by the I2C-bus master.
2. The reserved General Call address ‘0000 000’ with the R/W bit set to ‘0’ (write) is sent
by the I2C-bus master.
3. The PCA9952/55 device(s) acknowledge(s) after seeing the General Call address
‘0000 0000’ (00h) only. If the R/W bit is set to ‘1’ (read), no acknowledge is returned to
the I2C-bus master.
4. Once the General Call address has been sent and acknowledged, the master sends
1 byte with 1 specific value (SWRST data byte 1):
a. Byte 1 = 06h: the PCA9952/55 acknowledges this value only. If byte 1 is not equal
to 06h, the PCA9952/55 does not acknowledge it.
If more than 1 byte of data is sent, the PCA9952/55 does not acknowledge any more.
5. Once the correct byte (SWRST data byte 1) has been sent and correctly
acknowledged, the master sends a STOP command to end the SWRST function: the
PCA9952/55 then resets to the default value (power-up value) and is ready to be
addressed again within the specified bus free time (tBUF).
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16-channel Fm+ I2C-bus 57 mA constant current LED driver
General Call address
SWRST data byte 1
S0 0 0 0 0 0 0 0A0 0 0 0 0 1 1 0AP
START condition
acknowledge
from slave
acknowledge
from slave
STOP
condition
002aac900
Fig 8. SWRST Call
The I2C-bus master must interpret a non-acknowledge from the PCA9952/55 (at any time)
as a ‘SWRST Call Abort’. The PCA9952/55 does not initiate a reset of its registers. This
happens only when the format of the SWRST Call sequence is not correct.
7.8 Individual brightness control with group dimming/blinking
A 31.25 kHz fixed frequency signal with programmable duty cycle (8 bits, 256 steps) is
used to control individually the brightness for each LED.
On top of this signal, one of the following signals can be superimposed (this signal can be
applied to the 16 LEDn outputs control registers LEDOUT0 to LEDOUT3):
A lower 122 Hz fixed frequency signal with programmable duty cycle (8 bits,
256 steps) is used to provide a global brightness control.
A programmable frequency signal from 15 Hz to every 16.8 seconds (8 bits,
256 steps) with programmable duty cycle (8 bits, 256 steps) is used to provide a
global blinking control.
1 2 3 4 5 6 7 8 9 10 11 12
252 254 256
251 253 255 1 2 3 4 5 6 7 8 9 10 11
Brightness Control signal (LEDn)
M × 256 × 125 ns
with M = (0 to 255)
(GRPPWM Register)
N × 125 ns
with N = (0 to 255)
(PWMx Register)
256 × 125 ns = 32 μs
(31.25 kHz)
Group Dimming signal
256 × 256 × 125 ns = 8.19 ms (122 Hz)
12345678
12345678
resulting Brightness + Group Dimming signal
002aaf935
Fig 9.
Minimum pulse width for LEDn Brightness Control is 125 ns.
Minimum pulse width for Group Dimming is 32 s.
When M = 1 (GRPPWM register value), the resulting LEDn Brightness Control + Group Dimming signal will have 1 pulse of the
LED Brightness Control signal (pulse width = N 125 ns, with ‘N’ defined in PWMx register).
This resulting Brightness + Group Dimming signal above shows a resulting Control signal with M = 8.
Brightness + Group Dimming signals
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16-channel Fm+ I2C-bus 57 mA constant current LED driver
8. Characteristics of the I2C-bus
The I2C-bus is for 2-way, 2-line communication between different ICs or modules. The two
lines are a serial data line (SDA) and a serial clock line (SCL). Both lines must be
connected to a positive supply via a pull-up resistor when connected to the output stages
of a device. Data transfer may be initiated only when the bus is not busy.
8.1 Bit transfer
One data bit is transferred during each clock pulse. The data on the SDA line must remain
stable during the HIGH period of the clock pulse as changes in the data line at this time
will be interpreted as control signals (see Figure 10).
SDA
SCL
Fig 10. Bit transfer
data line
stable;
data valid
change
of data
allowed
mba607
8.1.1 START and STOP conditions
Both data and clock lines remain HIGH when the bus is not busy. A HIGH-to-LOW
transition of the data line while the clock is HIGH is defined as the START condition (S). A
LOW-to-HIGH transition of the data line while the clock is HIGH is defined as the STOP
condition (P) (see Figure 11).
SDA
SCL
S
START condition
Fig 11. Definition of START and STOP conditions
P
STOP condition
mba608
8.2 System configuration
A device generating a message is a ‘transmitter’; a device receiving is the ‘receiver’. The
device that controls the message is the ‘master’ and the devices which are controlled by
the master are the ‘slaves’ (see Figure 12).
PCA9952_PCA9955
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16-channel Fm+ I2C-bus 57 mA constant current LED driver
SDA
SCL
MASTER
TRANSMITTER/
RECEIVER
SLAVE
RECEIVER
SLAVE
TRANSMITTER/
RECEIVER
MASTER
TRANSMITTER
MASTER
TRANSMITTER/
RECEIVER
I2C-BUS
MULTIPLEXER
SLAVE
Fig 12. System configuration
002aaa966
8.3 Acknowledge
The number of data bytes transferred between the START and the STOP conditions from
transmitter to receiver is not limited. Each byte of eight bits is followed by one
acknowledge bit. The acknowledge bit is a HIGH level put on the bus by the transmitter,
whereas the master generates an extra acknowledge related clock pulse.
A slave receiver which is addressed must generate an acknowledge after the reception of
each byte. Also a master must generate an acknowledge after the reception of each byte
that has been clocked out of the slave transmitter. The device that acknowledges has to
pull down the SDA line during the acknowledge clock pulse, so that the SDA line is stable
LOW during the HIGH period of the acknowledge related clock pulse; set-up time and hold
time must be taken into account.
A master receiver must signal an end of data to the transmitter by not generating an
acknowledge on the last byte that has been clocked out of the slave. In this event, the
transmitter must leave the data line HIGH to enable the master to generate a STOP
condition.
data output
by transmitter
data output
by receiver
SCL from master
S
START
condition
1
Fig 13. Acknowledgement on the I2C-bus
2
not acknowledge
acknowledge
89
clock pulse for
acknowledgement
002aaa987
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9. Bus transactions
PCA9952; PCA9955
16-channel Fm+ I2C-bus 57 mA constant current LED driver
slave address(1)
control register
S 1 1 0 A3 A2 A1 A0 0 A X D6 D5 D4 D3 D2 D1 D0 A
data for register D[7:0](2)
AP
START condition
R/W Auto-Increment flag
acknowledge
from slave
(1) Slave address shown for PCA9955.
(2) See Table 6 for register definition.
Fig 14. Write to a specific register
acknowledge
from slave
acknowledge
from slave
STOP
condition
002aae918
slave address(1)
control register
MODE1 register data(2)
S 1 1 0 A3 A2 A1 A0 0 A 1 0 0 0 0 0 0 0 A
A
START condition
R/W
acknowledge
from slave
MODE1
register selection
Auto-Increment on
ALLCALLADR register data
(cont.)
AP
acknowledge
from slave
acknowledge
from slave
MODE2 register data
A (cont.)
acknowledge
from slave
acknowledge
from slave
STOP
condition
002aae919
(1) Slave address shown for PCA9955.
(2) AI1, AI0 = 00. See Table 5 for Auto-Increment options.
Remark: Care should be taken to load the appropriate value here in the AI1 and AI0 bits of the MODE1 register for
programming the part with the required Auto-Increment options.
Fig 15. Write to all registers using the Auto-Increment feature
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xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxx x x x xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xx xx xxxxx
xxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxx x x
xxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxx xxx
slave address(1)
control register
PWM0 register data
S 1 1 0 A3 A2 A1 A0 0 A 1 0 0 0 1 0 1 0 A
A
START condition
R/W
acknowledge
from slave
PWM14 register data
PWM0
register selection
acknowledge
from slave
acknowledge
from slave
Auto-Increment on
register rollover
PWM15 register data
PWM0 register data
(cont.)
A
A
A
PWM1 register data
A (cont.)
acknowledge
from slave
PWM14 register data
PWM15 register data
A AP
acknowledge
from slave
acknowledge
from slave
acknowledge
from slave
acknowledge
from slave
acknowledge
from slave
STOP
condition
002aae920
This example assumes that AIF + AI[1:0] = 101b.
(1) Slave address shown for PCA9955.
Fig 16. Multiple writes to Individual Brightness registers only using the Auto-Increment feature


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16-channel constant current LED driver

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16-channel Fm+ I2C-bus 57 mA constant current LED driver
slave address(1)
control register
ReSTART
condition slave address(1)
data from MODE1 register
S 1 1 0 A3 A2 A1 A0 0 A 1 0 0 0 0 0 0 0 A Sr 1 1 0 A3 A2 A1 A0 1 A
A (cont.)
START condition
R/W
acknowledge
from slave
MODE1
register selection
Auto-Increment on
data from MODE2 register data from LEDOUT0
acknowledge
from slave
data from
EFLAG1 register
R/W
acknowledge
from slave
data from
MODE1 register
acknowledge
from master
(cont.) A A
A A (cont.)
acknowledge
from master
data from last read byte
(cont.)
AP
acknowledge
from master
acknowledge
from master
acknowledge
from master
not acknowledge STOP
from master condition
This example assumes that the MODE1[5] = 0 and MODE1[6] = 0.
(1) Slave address shown for PCA9955.
Fig 17. Read all registers using the Auto-Increment feature
002aae921
slave address(1)
data from register
data from register
S 1 1 0 A3 A2 A1 A0 1 A
A
data from register
AP
START condition
R/W acknowledge
from slave
acknowledge
from master
no acknowledge STOP
from master condition
002aae922
Remark: A read operation can be done without doing a write operation before it. In this case, the data sent out is from the
register pointed to by the control register (written to during the last write operation) with the Auto-Increment options in the
MODE1 register (written to during the last write operation).
(1) Slave address shown for PCA9955.
Fig 18. Read of registers
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