SC4508 Datasheet, PDF (1/10 Pages) Semtech Corporation – Buck or Buck-Boost(Inverting) Current Mode Controller

SC4508
Buck or Buck-Boost(Inverting)
Current Mode Controller
POWER MANAGEMENT
Description
The SC4508 is a low voltage current mode switching regu-
lator controller that drives a P-channel power MOSFET
with programmable switching frequency. It can be con-
figured in either buck or buck boost (inverting) convert-
ers. The converters can be operated from 2.7V to 15V
input voltage range. The typical operating supply current
is 3mA and a shutdown pin allows the user to turn the
controller off reducing it to less than 200µA. The output
voltage can adjusted by external resistor divider. The
switching frequency is programmable up to 1.5MHz,
allowing small inductor and capacitor values to minimize
PCB space. The operating current level is programmable
via an external sense resistor. Accessible reference volt-
age allows users to make output voltage as low as they
want.
Features
‹ Wide input voltage range 2.7V to 15V
‹ Programmable output voltage
‹ Programmable switching frequency up to 1.5MHz
‹ Buck or buck boost(inverting) configuration
‹ Current mode control with slope compensation
‹ Very low quiescent current in shutdown mode
‹ Accessible reference voltage
‹ MLPQ-12 package
Applications
‹ Low power point of use converters
‹ Single or multiple output low power converters
‹ Positive and/or negative output voltage
‹ DSL cards
‹ Graphic cards
‹ I/O cards
‹ Negative bias supplies
Typical Application Circuits
Vin
Vin
VDD
VREF
FB+
SC4508
CS
FB-
OUT
COMP
SS/SHDN GND OSC
VDD
VREF
FB+
SC4508
CS
FB-
OUT
COMP
SS/SHDN GND OSC
Revision: November 30, 2004
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