LT3958 Datasheet PDF - Linear Technology

www.Datasheet-PDF.com

LT3958
Linear Technology

Part Number LT3958
Description SEPIC and Inverting Converter
Page 28 Pages


LT3958 datasheet pdf
Download PDF
LT3958 pdf
View PDF for Mobile


No Preview Available !

FEATURES
n Wide Input Voltage Range: 5V to 80V
n Single Feedback Pin for Positive or Negative
Output Voltage
n Internal 3.3A/84V Power Switch
n Current Mode Control Provides Excellent Transient
Response
n Programmable Operating Frequency (100kHz to
1MHz) with One External Resistor
n Synchronizeable to an External Clock
n Low Shutdown Current < 1μA
n Internal 7.2V Low Dropout Voltage Regulator
n Programmable Input Undervoltage Lockout with
Hysteresis
n Programmable Soft-Start
n Thermally Enhanced QFN (5mm × 6mm) Package
APPLICATIONS
n Automotive
n Telecom
n Industrial
www.DataSheet4U.com
LT3958
High Input Voltage,
Boost, Flyback, SEPIC and
Inverting Converter
DESCRIPTION
The LT®3958 is a wide input range, current mode, DC/DC
converter which is capable of generating either positive
or negative output voltages. It can be configured as either
a boost, flyback, SEPIC or inverting converter. It features
an internal low side N-channel power MOSFET rated for
84V at 3.3A and driven from an internal regulated 7.2V
supply. The fixed frequency, current-mode architecture
results in stable operation over a wide range of supply
and output voltages.
The operating frequency of LT3958 can be set with an
external resistor over a 100kHz to 1MHz range, and can
be synchronized to an external clock using the SYNC pin.
A minimum operating supply voltage of 5V, and a low
shutdown quiescent current of less than 1μA, make the
LT3958 ideally suited for battery-powered systems.
The LT3958 features soft-start and frequency foldback
functions to limit inductor current during start-up.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No RSENSE and ThinSOT are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patents pending.
TYPICAL APPLICATION
VIN
12V TO 40V
High Efficiency Boost Converter
33μH
4.7μF 392k
VIN SW
EN/UVLO
GND
53.6k
LT3958
SGND
SENSE1
SYNC
RT SS
SENSE2
FBX
VC INTVCC
41.2k
300kHz
0.33μF 10k
4.7μF
10nF
4.7μF
s2
VOUT
48V
0.5A
464k
15.8k
3958 TA01a
Efficiency vs Output Current
100
VIN = 24V
95
90
85
80
75
70
0
100 200 300 400 500
OUTPUT CURRENT (mA)
3958 TA01b
3958f
1



No Preview Available !

LT3958
www.DataSheet4U.com
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN, EN/UVLO (Note 5)..............................................80V
SW ............................................................................84V
INTVCC .................................................... VIN + 0.3V, 15V
SYNC ..........................................................................8V
VC, SS.........................................................................3V
RT ............................................................................................... 1.5V
SENSE1, SGND .................. Internally Connected to GND
SENSE2..................................................................±0.3V
FBX ................................................................. –6V to 6V
Operating Temperature Range
(Note 2) ............................................. –40°C to 125°C
Maximum Junction Temperature........................... 125°C
Storage Temperature Range................... –65°C to 125°C
PIN CONFIGURATION
TOP VIEW
36 35 34 33 32 31 30
NC 1
NC 2
SENSE2 3
SGND 4
37
SGND
SENSE1 6
SW 8
SW 9
NC 10
38
SW
12 13 14 15 16 17
28 INTVCC
27 VIN
25 EN/UVLO
24 SGND
23 SGND
21 SW
20 SW
UHE PACKAGE
36-LEAD (5mm s 6mm) PLASTIC QFN
TJMAX = 125°C, θJA = 43°C/W, θJC = 5°C/W
EXPOSED PAD (PIN 37) IS SGND, MUST BE SOLDERED TO SGND PLANE
EXPOSED PAD (PIN 38) IS SW, MUST BE SOLDERED TO SW PLANE
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3958EUHE#PBF
LT3958EUHE#TRPBF
3958
36-Lead (5mm × 6mm) Plastic QFN
–40°C to 125°C
LT3958IUHE#PBF
LT3958IUHE#TRPBF
3958
36-Lead (5mm × 6mm) Plastic QFN
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
3958f
2



No Preview Available !

www.DataSheet4U.com
LT3958
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temp-
erature range, otherwise specifications are at TA = 25°C. VIN = 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VIN Operating Range
5 80 V
VIN Shutdown IQ
EN/UVLO = 0V
EN/UVLO = 1.15V
0.1 1
6
μA
μA
VIN Operating IQ
VIN Operating IQ with Internal LDO Disabled
SW Pin Current Limit
VC = 0.3V, RT = 41.2k
VC = 0.3V, RT = 41.2k, INTVCC = 7.5V
SENSE2 = SENSE1
1.6 2.2
350 400
l 3.3 4.0 4.6
mA
μA
A
SW Pin On Voltage
SENSE2 Input Bias Current
ISW = 2A
Current Out of Pin
180 mV
–65 μA
Error Amplifier
FBX Regulation Voltage (VFBX(REG))
FBX > 0V (Note 3)
FBX < 0V (Note 3)
l 1.569 1.6 1.631
l –0.816 –0.800 –0.784
V
V
FBX Overvoltage Lockout
FBX > 0V (Note 4)
FBX < 0V (Note 4)
6 8 10
7 11 14
%
%
FBX Pin Input Current
FBX = 1.6V (Note 3)
FBX = –0.8V (Note 3)
70 100
–10 10
nA
nA
Transconductance gm (ΔIVC /ΔFBX)
VC Output Impedance
(Note 3)
(Note 3)
230 μS
5 MΩ
VFBX Line Regulation (ΔVFBX/[ΔVIN • VFBX(REG)])
VC Current Mode Gain (ΔVVC /ΔVSENSE)
VC Source Current
FBX > 0V, 5V < VIN < 80V (Notes 3, 6)
FBX < 0V, 5V < VIN < 80V (Notes 3, 6)
VC = 1.5V, FBX = 0V, Current Out of Pin
0.006
0.005
10
–15
0.03
0.038
%/ V
%/ V
V/ V
μA
VC Sink Current
FBX = 1.7V
FBX = –0.85V
12 μA
11 μA
Oscillator
Switching Frequency
RT Voltage
RT = 140k to SGND, FBX = 1.6V, VC = 1.5V
RT = 41.2k to SGND, FBX = 1.6V, VC = 1.5V
RT = 10.5k to SGND, FBX = 1.6V, VC = 1.5V
FBX = 1.6V
80 100 120
270 300 330
850 1000 1200
1.2
kHz
kHz
kHz
V
SW Minimum Off-Time
200 275
ns
SW Minimum On-Time
250 300
ns
SYNC Input Low
0.4
SYNC Input High
1.5
SS Pull-Up Current
SS = 0V, Current Out of Pin
–10 μA
Low Dropout Regulator
INTVCC Regulation Voltage
INTVCC Undervoltage Lockout Threshold
Falling INTVCC
UVLO Hysteresis
l7
7.2 7.4
3.55 3.75 4.00
0.15
V
V
V
INTVCC Overvoltage Lockout Threshold
11.5 12.8
V
3958f
3



No Preview Available !

LT3958
www.DataSheet4U.com
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temp-
erature range, otherwise specifications are at TA = 25°C. VIN = 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
INTVCC Current Limit
INTVCC Load Regulation (ΔVINTVCC / VINTVCC)
INTVCC Line Regulation (ΔVINTVCC / [ΔVIN • VINTVCC])
Dropout Voltage (VIN – VINTVCC)
INTVCC Current in Shutdown
INTVCC Voltage to Bypass Internal LDO
Logic Inputs
VIN = 80V
VIN = 20V
0 < IINTVCC < 10mA, VIN = 8V
8V < VIN < 80V
VIN = 6V, IINTVCC = 10mA, VC = 0V
EN/UVLO = 0V, INTVCC = 8V
19 24 29
50
–1 –0.4
0.005 0.025
500
16
7.5
mA
mA
%
%/ V
mV
μA
V
EN/UVLO Threshold Voltage Falling
EN/UVLO Voltage Hysteresis
VIN = INTVCC = 8V
l 1.17 1.22 1.27
20
V
mV
EN/UVLO Input Low Voltage
EN/UVLO Pin Bias Current Low
IVIN Drops Below 1μA
EN/UVLO = 1.15V
0.4
1.7 2 2.5
V
μA
EN/UVLO Pin Bias Current High
EN/UVLO = 1.33V
10 100
nA
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT3958E is guaranteed to meet performance specifications
from the 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3958I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3: The LT3958 is tested in a feedback loop which servos VFBX to the
reference voltages (1.6V and –0.8V) with the VC pin forced to 1.3V.
Note 4: FBX overvoltage lockout is measured at VFBX(OVERVOLTAGE) relative
to regulated VFBX(REG).
Note 5: For 5V < VIN < 6V, the EN/UVLO pin must not exceed VIN.
Note 6: EN/UVLO = 1.33V when VIN = 5V.
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted.
Positive Feedback Voltage
vs Temperature, VIN
1.604
1.602
VIN = 80V
1.600
1.598
1.596
VIN = 24V
VIN = 8V
1.594
1.592
VIN = INTVCC = 5V
1.590
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3958 G01
Negative Feedback Voltage
vs Temperature, VIN
–792
–794
–796
–798
–800
–802
VIN = INTVCC = 5V
VIN = 8V
VIN = 24V
VIN = 80V
–804
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3958 G02
4
Quiescent Current
vs Temperature, VIN
1.8
VIN = 80V
1.7
VIN = 24V
1.6
VIN = INTVCC = 5V
1.5
1.4
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3958 G03
3958f



LT3958 datasheet pdf
Download PDF
LT3958 pdf
View PDF for Mobile


Related : Start with LT395 Part Numbers by
LT3952 60V LED Driver LT3952
Linear
LT3952 pdf
LT3954 40V IN LED Converter LT3954
Linear Technology
LT3954 pdf
LT3955 LED Converter LT3955
Linear
LT3955 pdf
LT3956 Constant-Current and Constant-Voltage Converter LT3956
Linear Technology
LT3956 pdf
LT3957 SEPIC and Inverting Converter LT3957
Linear Technology
LT3957 pdf
LT3957A Boost / Flyback / SEPIC and Inverting Converter LT3957A
Linear Technology
LT3957A pdf
LT3958 SEPIC and Inverting Converter LT3958
Linear Technology
LT3958 pdf
LT3958 SEPIC and Inverting Converter LT3958
Linear Technology
LT3958 pdf

Index :   0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z   

This is a individually operated, non profit site. If this site is good enough to show, please introduce this site to others.
Since 2010   ::   HOME   ::   Contact