LT3959_15 Datasheet, PDF (1/26 Pages) Linear Technology – Wide Input Voltage Range Boost/SEPIC/Inverting Converter with 6A, 40V Switch

LT3959
Features
Wide Input Voltage Range
Boost/SEPIC/Inverting Converter
with 6A, 40V Switch
Description
n _{Wide VIN Range: 1.6V (2.5V Start-Up) to 40V}
n _{Positive or Negative Output Voltage Programming}
with a Single Feedback Pin
n _{PGOOD Output Voltage Status Report}
n _{Internal 6A/40V Power Switch}
n _{Programmable Soft-Start}
n _{Programmable Operating Frequency (100kHz to 1MHz)}
with One External Resistor
n _{Synchronizable to an External Clock}
n _{Low Shutdown Current < 1µA}
n _{INTVCC Regulator Supplied from VIN or DRIVE}
n _{Programmable Input Undervoltage Lockout with}
Hysteresis
n _{Thermally Enhanced QFN (5mm × 6mm) and TSSOP}
Packages
Applications
n _Automotive
n _Telecom
n _Industrial
The LT^®3959 is a wide input range, current mode, DC/DC
controller which is capable of regulating either positive or
negative output voltages from a single feedback pin. It can
be configured as a boost, SEPIC or inverting converter.
It features an internal low side N-channel MOSFET rated
for 6A at 40V and driven from an internal regulated sup-
ply provided from V_IN or DRIVE. The fixed frequency,
current-mode architecture results in stable operation over
a wide range of supply and output voltages. The operating
frequency of LT3959 can be set over a 100kHz to 1MHz
range with an external resistor, or can be synchronized
to an external clock using the SYNC pin.
The LT3959 features soft-start and frequency foldback
functions to limit inductor current during start-up and
output short-circuit. A window comparator on the FBX
pin reports via the PGOOD pin, providing output voltage
status indication.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 7825665.
Typical Application
2.5V to 24V Input, 12V Output SEPIC Converter
Excellent for Automotive 12V Post Regulator
V_IN
2.5V TO
24V
4.7µF
L1A
50V
C_IN
22µF
50V
×2
150k
124k
121k
V_IN
EN_UVLO
SW
L1B
LT3959 _GND
27.4k
300kHz
TIE TO SGND
IF NOT USED
PGOOD
SYNC
DRIVE
RT
SS
FBX
V_C SGND GNDK INTV_CC
105K
0.1µF 7.5k
22nF
15.8K
4.7µF
COUT
47µF
16V
×2
V_OUT
12V
500mA AT V_IN = 2.5V
1.5A AT V_IN > 8V
3959 TA01a
For more information www.linear.com/LT3959
Efficiency vs Output Current
100
V_IN = 12V
95
90
85
80
75
70
65
60
0
200 400 600 800 1000
OUTPUT CURRENT (mA)
3959 TA01b
3959fa
1