TPS40074_15 Datasheet, PDF (1/42 Pages) Texas Instruments – MIDRANGE INPUT SYNCHRONOUS BUCK CONTROLLER WITH VOLTAGE FEED-FORWARD

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TPS40074
SLUS617B – APRIL 2005 – REVISED OCTOBER 2006
MIDRANGE INPUT SYNCHRONOUS BUCK CONTROLLER
WITH VOLTAGE FEED-FORWARD
FEATURES
• Operation Over 4.5-V to 28-V Input Range
• Fixed-Frequency Voltage-Mode Controller
• Integrated Unity Gain Amplifier for Remote
Output Sensing
• Predictive Gate Drive™ Generation II for
Improved Efficiency
• <1% Internal 700-mV Reference
• Input Voltage Feed Forward Control
• Prebiased Output Compatible
• Internal Gate Drive Outputs for High-Side and
Synchronous N-Channel MOSFETs
• Switching Frequency Programmable to 1 MHz
• 20-Pin QFN Package
• Thermal Shutdown Protection
• Software Design Tool and EVM Available
APPLICATIONS
• Power Modules
• Networking/Telecom
• Industrial
• Servers
DESCRIPTION
The TPS40074 is a mid voltage, wide input (4.5-V to
28-V), synchronous, step-down controller, offering
design flexibility for a variety of user programmable
functions, including; soft start, UVLO, operating
frequency, voltage feed-forward and high-side FET
sensed short circuit protection.
The TPS40074 incorporates MOSFET gate drivers
for external N-channel high side and synchronous
rectifier (SR) MOSFETs. The gate drive logic
incorporates second generation predictive anti-cross
conduction circuitry to prevent simultaneous high
side and synchronous rectifier conduction, while
minimizing to eliminating current flow in the body
diode of the SR FET. The TPS40074 allows for
starting into pre-biased outputs by not allowing the
synchronous rectifier FET to turn on until the
commanded voltage during soft start is greater than
the existing pre-bias voltage.
The TPS40074 uses voltage feed-forward control
techniques to provide good line regulation over a
wide input voltage range, and fast response to input
line transients. Voltage feed-forward also provides
nearly constant power stage gain with input variation
to ease loop compensation of wide input range
designs. The externally programmable short circuit
protection provides fault current limiting, as well as
hiccup mode operation for low power dissipation in
the presence of a shorted output. The TPS40074 is
packaged in a 20-pin QFN package for better
thermal performance at higher voltages and
frequencies, as well as reduced footprint.
SIMPLIFIED APPLICATION DIAGRAM
V_OUT−
V_OUT+
(at Load) (at Load)
1
20
SA−
SA+
TPS 40074
2 SAO
SYNC 19
3 GND
PGD 18
4 SS
LVBP 17
5 FB
RT 16
6 COMP
KFF 15
SYNC IN
PowerGood OUT
7 PGND
ILIM 14
V_IN
8 LDRV
VDD 13
9 DBP
SW
10
HDRV 12
BOOST
11
V_OUT−
V_OUT+
UDG−04075
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Predictive Gate Drive is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2005–2006, Texas Instruments Incorporated