SC4508A Datasheet, PDF (1/21 Pages) Semtech Corporation – Buck or Buck-Boost (Inverting) Current Mode Controller

SC4508A
Buck or Buck-Boost (Inverting)
Current Mode Controller
POWER MANAGEMENT
Description
The SC4508A is a low voltage current mode switching
regulator controller that drives a P-channel power
MOSFET with programmable switching frequency. It can
be configured in either buck or buck boost (inverting) con-
verters. 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 di-
vider. The switching frequency is programmable up to
1.5MHz, allowing small inductor and capacitor values to
minimize PCB space. The operating current level is pro-
grammable via an external sense resistor. Accessible ref-
erence voltage 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
‹ Hiccup mode after 32 cycle-by-cycle OCP
‹ 4mm x 4mm MLPQ-12 lead free package. This
product is fully WEEE and RoHS compliant
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
V+
VREF
FB+
FB-
COMP
SC4508A
CS
OUT
SS/EN
GND OSC
Vout
V+
VREF
FB+
FB-
COMP
SC4508A
CS
OUT
SS/EN
GND OSC
Vout
Revision: July 25, 2007
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