LM2746 Datasheet, PDF (1/24 Pages) National Semiconductor (TI) – Low Voltage N-Channel MOSFET Synchronous Buck Regulator Controller

May 2005
LM2746
Low Voltage N-Channel MOSFET Synchronous Buck
Regulator Controller
General Description
The LM2746 is a high-speed synchronous buck regulator
controller with a feedback voltage accuracy of ±1%. It can
provide simple down conversion to output voltages as low as
0.6V. Though the control sections of the IC are rated for 3 to
5.5V, the driver sections are designed to accept input supply
rails as high as 16V. The use of non-overlapping MOSFET
gate drivers helps avoid potential shoot-through problems
while maintaining high efficiency. The IC is designed for the
more cost-effective option of driving only N-channel MOS-
FETs in both the high-side and low-side positions. It senses
the low-side switch voltage drop for providing a simple,
adjustable current limit.
The fixed-frequency voltage-mode PWM control architecture
is adjustable from 50 kHz to 1 MHz with one external resis-
tor. This wide range of switching frequency gives the power
supply designer the flexibility to make better tradeoffs be-
tween component size, cost and efficiency.
Features include soft-start, input undervoltage lockout
(UVLO) and Power Good (based on both undervoltage and
overvoltage detection). In addition, the shutdown pin of the
IC can be used for providing startup delay, and the soft-start
pin can be used for implementing precise tracking, for the
purpose of sequencing with respect to an external rail.
Features
n Power stage input voltage from 1V to 16V
n Control stage input voltage from 3V to 5.5V
n Output voltage adjustable down to 0.6V
n Power good flag and shutdown
n Output overvoltage and undervoltage detection
n ±1% feedback voltage accuracy over temperature
n Low-side adjustable current sensing
n Adjustable soft-start
n Tracking and sequencing with shutdown and soft start
pins
n Switching frequency from 50 kHz to 1 MHz
n Exposed pad TSSOP-14 package
Applications
n Cable Modem, DSL and ADSL
n Laser Jet and Ink Jet Printers
n Low Voltage Power Modules
n DSP, ASIC, Core and I/O
Typical Application
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