November 2012
SG1577
Dual Synchronous DC/DC Controller
Features
Description
The SG1577 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 0.7 V ±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 0.55 mA. The fixed-
frequency is programmable from 60 kHz to 320 kHz.
The Over-Current Protection (OCP) level can be
programmed by an external current sense resistor. It
has two integrated sets of internal MOSFET drivers.
SG1577 is available in the 20-pin SOP package.
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Integrated Two Sets of MOSFET Drivers
Two Independent PWM Controllers
Constant Frequency Operation: Free-running Fixed
Frequency Oscillator Programmable: 60 kHz to
320 kHz
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Wide Range Input Supply Voltage: 8~15 V
Programmable Output as Low as 0.7 V
Internal Error Amplifier Reference Voltage:
0.7 V ±1.5%
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Two Soft-Start / EN Functions
Programmable Over-Current Protection (OCP)
30 V HIGH Voltage Pin for Bootstrap Voltage
Output Over-Voltage Protection (OVP)
SOP 20-Pin
Applications
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CPU and GPU Vcore Power Supply
Power Supply Requiring Two Independent Outputs
Ordering Information
Operating
Temperature Range
Packing
Part Number
Package
Method
SG1577SY
-40°C to +85°C
20-Lead, Small Outline Package (SOP-20)
Tape & Reel
© 2009 Fairchild Semiconductor Corporation
SG1577 • Rev. 1.0.6
www.fairchildsemi.com