XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
XN1049 Switch Power Supply PWM Controller
General Description
XN1049 which is optimized for high performance is a
highly integrated current mode PWM control IC. It is
applied for switch power of the small-sized and
medium-sized for example the power adaptor. For
lower the standby power and higher RoHS compliant,
the IC has the Burst Mode function and very low
startup current and working current. At the condition
of no load or light load, the IC operates in extended
‘burst mode’ to minimize switching loss by lower the
switching frequency. The low startup current and low
operating current contribute to a reliable power on
startup design with XN1049. A large value resistor
could thus be used in the startup circuit to minimize
the power consumption and improve the efficiency of
the power convent.
The internal synchronous slope compensation circuit
improves system large signal stability and reduces the
possible subharmonic oscillation at high PWM duty
cycle output. Leading-edge blanking on current
sense(CS) input removes the signal glitch due to
snubber circuit diode reverse recovery and thus
greatly reduces the external component count and
system cost in the design. XN1049 offers complete
protection coverage with automatic self-recovery
feature including over current protection cycle by
cycle (OCP), over load protection (OLP), under
voltage lockout (UVLO). The gate-driven output is
clamped to maximum 18V to protect the external
MOSFET. Excellent EMI performance is achieved by
using the frequency jitter and the soft-switching at the
totem-pole-gate-drive output. The tone energy at
below 20KHZ is minimized in the design and audio
noise is eliminated during operation. The IC can be
used as the best alternative products of the linear
power supply or the RCC-mode power to improve the
whole performance of the switch power system and
lower the cost. XN1049 is offered in SOT23-6, SOP-8
and DIP-8 packages.
Features
„ Extended burst mode control for improving
efficiency and minimum standby power
„ Low startup current(4uA)
„ Low operation current(1.4mA)
„ Leading edge blanking was built in
„ Synchronous slope compensation was built in
„ Current mode operates
„ External programmable PWM switching
frequency
„ Over current protection cycle by cycle(OCP)
„ Good protection coverage with auto self-
recovery
„ VDD over voltage clamp and under voltage
lockout with hysteresis (UVLO)
„ Maximum gate-drive output clamped voltage
(18V)
„ Frequency jitter
„ Constant limited output power
„ Over load protection(OLP)
„ Free audio noise operation
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 1
June, 2008
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
Applications
Universal switch power supply and offline AC/DC
flyback converter:
„ Battery Charger
„ Power Adaptor
„ Set-Top Box Power Supplies
„ Open-frame SMPS
Typical Application Circuit
Pin Definition and Device Marking
1
GND
6
GATE
2
FB
3
RI
SOT23-6
5
VDD
4
SENSE
1
GATE
2
VDD
3
NC
4
SENSE
DIP8
SOP8
8
GND
7
FB
6
NC
5
RI
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
49: XN1049
Y: Year Code
WWWeek Code
Page 2
X: D = DIP8 S = SOP8
P: P = Pb-free package
Y: Year Code (0-9)
WW: Week Code (1-52)
X: Area Code
V: Internal Version Code (1-9)
June, 2008
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
Ordering Information
Package
8-Pin DIP8, Pb-free
8-Pin SOP8, Pb-free
6-Pin SOT23-6, Pb-free
IC Marking Information
XN1049DP
XN1049SP
49 YWW
Purchasing Device Name
XN1049DP
XN1049SP
XN1049TPSOT23-6
Pin Function Description
Pin Name Pin No.
Pin Type
GND
DIP8/SOP8
8 / 1 Ground
Feedback
FB 7 / 2
Input
Frequency
RI 5 / 3
Setting
NC 3 Floating
NC 6 Floating
SENSE
Current
4/4
Monitoring
VDD
2 / 5 Power
GATE
1 / 6 Output
Function Description
Ground
Feedback input pin. The PWM duty cycle is determined by voltage
into this pin and the current-sense signal at Pin 4
Internal oscillator frequency setting pin. A resistor which is
connected between RI and GND sets the PWM frequency
Floating
Floating
Current detection flyback input pin for estimating reaching the limit
DC power supply pin
Totem-pole gate drive output for the power MOSFET
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 3
June, 2008
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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Block Diagram
XN1049 Switch Power Supply PWM Controller
Absolute Maximum Ratings
Symbol
Parameter
Value
Unit
VDD
Input Voltage
30 V
VFB Input Voltage to FB
-0.3~7
V
VSENSE
VRI
TJ
Input Voltage to Sense Pin
Input Voltage to RI Pin
Work junction temperature
-0.3~7
-0.3~7
-20~150
V
V
TSTG Storage temperature
-55~160
VCV VDD setting voltage
34 V
ICC VDD DC setting voltage
10 mA
Note: Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress
ratings only, functional operation of the device at these or any other conditions beyond those indicated under “recommended
operating conditions” is not implied. Exposure to absolute maximum-rated conditions for extended periods may affect device
reliability.
Recommended Operating Condition
Symbol
VDD
RI
TA
Parameter
VDD supply voltage
RI resistor value
Operating temperature
Value
10 to 30
100
-20 to 85
Unit
V
Kohm
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 4
June, 2008
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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ESD Information
XN1049 Switch Power Supply PWM Controller
Symbol
VESD-HBM
VESD-MM
Parameter
Value
Human body model on all pins except 3
Vin and VDD
Machine model on all pins
150
Electrical Characteristics
Unit
KV
V
Supply Voltage (VDD)
symbol
parameter
Test condition
VDD_OP
Operation voltage
UVLO_ON
Turn on threshold Voltage
UVLO_OFF Turn-off threshold Voltage
I_VDD_ST
Start up current
VDD=13V,RI=100K
I_VDD_OP
Operation Current
VDD=16V,RI=100K,VFB=3V,
GATE with 1nF to GND
VDD_Clamp VDD Zener Clamp Voltage
Feedback Input Section
IVDD=10mA
VFB_Open
IFB_Short
VTH_PL
TD_PL
ZFB_IN
Max_Duty
VFB Open Loop Voltage
FB Pin Short Current
Power limiting FB Threshold
Power limiting Debounce
Input Impedance
Maximum duty cycle
FB Shorted to GND
Current Sense Section
TLEB
Zsense
TD_OC
TTH_OC
Leading edge Blanking Time
Input impedance
OCP control delay
OCP threshold
GATE with 1nF to GND
FB3V
Oscillator Section
Fosc Frequency
Oscillation
@RI=100K,CS=0,FB=3V
Fosc_BM
Burst mode frequency
Oscillation
@RI=100K,CS=0,FB=1.1V
f_temp
Frequency variation versus TEMP = -20 to 85
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 5
Min Typ Max Unit
30 V
7.5 8.5 9.5 V
13.5 14.3 15.5 V
4 20 uA
1.4 2.4 mA
33 V
4.5 4.9 5.5 V
0.8 mA
3.65 V
47 ms
6 k
75 %
330 ns
40 k
120 ns
0.70 0.75 0.80 V
60 65 70 KHz
22 KHz
5%
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
temp. Deviation
f_VDD
Frequency variation versus VDD = 12 to 25V
VDD
V_RI_Open
RI open Load Voltage
RI_range
50
GATE Output Section
VOL
VOH
VClamp
Tr
Output voltage low
Output voltage high
Output clamp voltage
Rising time
VDD = 16V, Io = -20mA
VDD = 16V, Io = 20mA
10
VDD = 16V, GATE with 1nF to
GND
Tf Falling time
VDD = 16V, GATE with 1nF to
GND
5%
2V
100 150 k
0.8
18
200
V
V
V
ns
70 ns
Typical Operating Characteristics
UVLO(ON) vs Temperature
8.80
8.75
8.70
8.65
8.60
8.55
-25
5 35 65 95
Temperature()
125
UVLO(OFF) vs Temperature
14.05
14.00
13.95
13.90
13.85
13.80
-25
5 35 65 95
Temperature()
125
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 6
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
1.2
1
0.8
0.6
0.4
0.2
0
0
IVDD vs VDD
10 20
VDD(V)
30
IVDD_startup vs VDD
20
15
10
5
0
0 2 4 6 8 10 12 14
VDD(V)
I_Vdd vs Gate load
5
4
3
2
1
0
0 500 1000 1500 2000
load(pF)
50KHz
65KHz
100KHz
Fosc vs Temperature
65.5
65.0
64.5
64.0
63.5
63.0
62.5
62.0
-25
5 35 65 95
Temperature()
125
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 7
June, 2008
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
Function Description
XN1049 is a highly integrated current mode PWM
control IC which is optimized for high performance. It is
applied for switch power of the small-sized and
medium-sized for example the power adaptor. The
knockdown startup current, operation current and burst
mode function at the condition of no load and low load
can decrease the standby cost of the power supply system
effectively, and improve the power convert efficiency.
The internal synchronous slope compensation, the leading
edge blanking function of the flyback pin not only
decrease the component number, but also improve the
stability of the system and avoid the harmonics generation.
XN1049 also have multiform general recovery protection
mode. The main function is described as below.
Startup Current and Startup Control
Startup current of XN1049 is designed to be very low at
4μA so that VDD could be charged up above UVLO
threshold level and device starts up quickly. A large value
startup resistor can therefore be used to minimize the
power loss, predigest the design of startup circuit and
provides reliable startup in application. For the design of
AC/DC adaptor with universal input range, a startup
resistor of 2 M, 1/8 W could be used together with a
VDD capacitor to provide a fast startup and low power
dissipation solution.
Operating Current
The operating current of XN1049 is low at 1.4mA. Good
efficiency is achieved with low operating current together
and extended burst mode control circuit which can
decrease the requirement of the VDD hold capacitor.
Extended Burst Mode Operation
At the condition of zero load or light load, most of the
power dissipation in a switching mode power supply is
from switching loss on the MOSFET transistor, the core
loss of the transformer and the loss on the snubber circuit.
The magnitude of power loss is in proportion to the number
of switching events within a period of time. Reducing
switching events leads to the reduction on the power loss
and thus conserves the energy. XN1049 self adjusts the
switching mode according to the loading condition. At the
condition of no load or light/medium load, the FB input
drops below burst mode threshold level. Device enters
Burst Mode control on the basis of the judgment. The gate
drive output switches only when VDD voltage drops below
a preset level and FB input is active. Otherwise the gate
drive remains at off-state to minimize the switching loss
and reduces the standby power consumption to the greatest
extend. The frequency control also eliminates the audio
noise at any loading conditions.
Oscillator Operation
A resistor connected between RI and GND sets the
charge/discharge time of the constant current source to the
internal cap and thus the PWM oscillator frequency is
determined. The relationship between RI and switching
frequency follows the below equation
within the specified RI in Kohm range at nominal loading
operational condition.
Fosc
=
6500
RI (Kohm)
(Khz)
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
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XN1049 (Innuovo)
Switch Power Supply PWM Controller

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XN1049 Switch Power Supply PWM Controller
Current Sensing and Leading Edge Blanking
Cycle-by-Cycle current limiting is offered in XN1049
current mode PWM control. The switch current is
detected by a sense resistor into the sense pin. An internal
leading edge blanking circuit chops off the sense voltage
spike at initial MOSFET on state due to snubber diode
reverse recovery so that the external RC filtering on sense
input is no longer required. The current limit comparator
is disabled and thus cannot turn off the external MOSFET
during the blanking period. PWM duty cycle is
determined by the current sense input voltage and the FB
input voltage.
Internal Synchronized Slope Compensation
Built-in slope compensation circuit adds slope voltage
onto the current sense input voltage for PWM generation.
This greatly improves the close loop stability at CCM and
prevents the sub-harmonic oscillation and thus reduces
the output ripple voltage.
Gate Drive
The GATE of XN1049 is connected to the gate of an
external MOSFET for power switch control. The gate
drive strength which is too weak results in over switch loss
of MOSFET while too strong gate drive output
compromises the over EMI. A good tradeoff which is in
output strength and dead time control is achieved through
the design of the built-in totem pole gate. The low standby
loss and good EMI system design is easier to achieve with
this dedicated control scheme. An internal 18V clamp is
added for MOSFET gate protection at higher than expected
VDD input.
Protection Controls
Good power supply system reliability is achieved with its
rich protection features including Cycle-by-Cycle current
limiting (OCP), Over Load Protection (OLP) and over
voltage clamp, Under Voltage Lockout on VDD (UVLO).
The built-in OCP protection circuit can detect the average
of the PWM signal effectively. At overload condition when
FB input voltage exceeds power limit threshold value for
more than TD_PL, control circuit reacts to shut down the
output power MOSFET. Device restarts when VDD voltage
drops below UVLO limit. It is clamped when VDD is
higher than threshold value. The power MOSFET is shut
down when VDD drops below UVLO limit and device
enters power on start-up sequence thereafter.
Xi’an Innuovo Microelectronics Co., Ltd.
DS.XN1049V1.0
Page 9
June, 2008
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