SG1577A_10 Datasheet, PDF (1/15 Pages) Fairchild Semiconductor – Dual Synchronous DC/DC Controller

August 2010
SG1577A
Dual Synchronous DC/DC Controller
Features
ƒ Integrated Two Sets of MOSFET Drivers
ƒ Two Independent PWM Controllers
ƒ Constant Frequency Operation: Free-Running
Fixed Frequency Oscillator Programmable:
61kHz to 340kHz
ƒ Maximum Input Supply Voltage: 15V
ƒ Programmable Output as Low as 0.7V
ƒ Internal Error Amplifier Reference Voltage:
0.7V±1.5%
ƒ Two Soft-Start / EN Functions
ƒ Programmable Over-Current Protection (OCP)
ƒ 30V HIGH Voltage Pin for Bootstrap Voltage
ƒ Output Over-Voltage Protection (OVP)
ƒ 20-Pin SOP
Applications
ƒ CPU and GPU Vcore Power Supply
ƒ Power Supply Requiring Two Independent Outputs
Description
The SG1577A is a high-efficiency, voltage-mode, dual-
channel, synchronous DC/DC PWM controller for two
independent outputs. The two channels are operated
out of phase. The internal reference voltage is trimmed
to 0.7V±1.5%. It is connected to the error amplifier’s
positive terminal for voltage feedback regulation.
The soft-start circuit ensures the output voltage can be
gradually and smoothly increased from zero to its final
regulated value. The soft-start pin can also be used for
chip-enable function. When two soft-start pins are
grounded, the chip is disabled and the total operation
current can be reduced to under 0.7mA.
The fixed-frequency is programmable from 60kHz to
340kHz. The Over-Current Protection (OCP) level can
be programmed by an external current-sense resistor. It
has two integrated sets of internal MOSFET drivers.
SG1577A is available in a 20-pin SOP package.
Ordering Information
Part Number
SG1577ASY
Operating Temperature Range
-40°C to +105°C
Package
20-Lead, Small Outline Package
(SOP-20)
Packing Method
Tape & Reel
© 2009 Fairchild Semiconductor Corporation
SG1577A • Rev. 1.0.2
www.fairchildsemi.com