Low Power Dual Synchronous DC/DC
Controller With Current Sharing Circuitry
POWER MANAGEMENT
Description
The SC1175 is a versatile 2 phase, synchronous, voltage mode
PWM controller that may be used in two distinct ways. First, the
SC1175 is ideal for applications where point of use output power
exceeds any single input power budget. Alternatively, the SC1175
can be used as a dual switcher. The SC1175 features a tempera-
ture compensated voltage reference, over current protection with
50% fold-back and internal level-shifted, high-side drive circuitry.
In current sharing configuration, the SC1175 can produce a single
output voltage from two separate voltage sources (which can be
different voltage levels) while maintaining current sharing between
the channels. Current sharing is programmable to allow loading
each input supply as required by the application.
In dual switcher configuration, two feedback paths are provided
for independent control of the separate outputs. The device will
provide a regulated output from flexibly configured inputs (3.3V,
5V, 12V), provided 5V is present for V
CC
. The two switchers are
180° out of phase to minimize input and output ripple.
SC1175
Features
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300kHz fixed frequency operation
Soft Start and Enable function
Power Good output provided
Over current protection with 50% fold-back
Phase-shifted switchers minimize ripple
High efficiency operation, >90%
Programmable output(s) as low as 1.25V
Industrial temperature range
SOIC 20 pin package
Two Phase, Current Sharing Controller
Flexible, same or separate V
IN
Programmable current sharing
Combined current limit with fold-back
2 phases operating opposed for ripple reduction
Thermal distribution via multi-phase output
Applications
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Graphics cards
DDR Memory
Peripheral add-in card
SSTL Termination
Dual-Phase power supply
Power supplies requiring two outputs
Two Independent PWM Controllers
Flexible, same or separate V
IN
Independent control for each channel
Independent and separate current limit
2 phases operating opposed for ripple reduction (if same
V
IN
used)
Typical Application Circuit
2 Channels with Current Sharing
Revision 7/31/2000
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