LTC3901_15 Datasheet, PDF (1/16 Pages) Linear Technology – Secondary Side Synchronous Driver for Push-Pull and Full-Bridge Converters

LTC3901
Secondary Side
Synchronous Driver for Push-Pull
and Full-Bridge Converters
FEATURES
■ _{N-Channel Synchronous MOSFET Driver}
■ _{Programmable Timeout}
■ _{Reverse Inductor Current Sense}
■ _{Gate Drive Transformer Synchronization}
Sequence Monitor
■ _{Wide VCC Supply Range: 4.5V to 11V}
■ _{15ns Rise/Fall Times at VCC = 5V, CL = 4700pF}
■ _{Undervoltage Lockout}
■ _{Small 16-Lead SSOP Package}
U
APPLICATIO S
■ _{48V Input Isolated DC/DC Converters}
■ _{Isolated Telecom Power Supplies}
■ _{Distributed Power Step-Down Converters}
■ _{Industrial Control System Power Supplies}
■ _{Automotive and Heavy Equipment}
DESCRIPTIO
The LTC^®3901 is a secondary side synchronous rectifier
driver designed to be used in isolated push-pull and full-
bridge converter power supplies. The chip drives two
external N-channel MOSFETs and accepts a transformer-
generated bipolar input to maintain sychronization with
the primary side controller.
The LTC3901 provides a full range of protection features
for the external MOSFETs. A programmable timeout func-
tion is included that disables both drivers when the syn-
chronization signal is missing or incorrect. Additionally,
the chip senses the output inductor current through the
drain-source resistance of the two MOSFETs, turning off
the MOSFETs if the inductor current reverses. The LTC3901
also shuts off the drivers if the supply is low or if the
synchronization sequence is incorrect.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
V_IN
36V TO 72V
ISOLATION
BARRIER
T1
MA
MB
ME
DRVA
DRVB
LTC3723
PUSH-PULL
CONTROLLER
COMP V_FB SDRA SDRB
MF
T2
L1
CSE+
V_CC
ME
CSE–
GND
LTC3901
CSF+
PV_CC
MF
CSF–
PGND
SYNC TIMER
OUT
FB
LT4430 OR LT1431
OPTOCOUPLER
DRIVER
COMP
Figure 1. Simplified Isolated Push-Pull Converter
+
C_OUT
V_OUT
12V
3901 F01
3901f
1