POWER MANAGEMENT
1
www.semtech.com
SC4508
Buck or Buck-Boost(Inverting)
Current Mode Controller
Description
Revision: October 14, 2004
Features
Typical Application Circuits
Applications
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
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
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 200
A. 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.
VREF
CS
OUT
VDD
FB+
FB-
COMP
SS/SHDN
OSC
SC4508
Vin
GND
CS
OSC
VDD
Vin
SS/SHDN
FB-
GND
SC4508
OUT
FB+
VREF
COMP
2
2004 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
SC4508
Electrical Characteristics
Absolute Maximum Rating
Unless specified: V
DD
= 2.7V to 15V , T
A
= T
J
= -40C to 125C
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Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters
specified in the Electrical Characteristics section is not implied.
3
2004 Semtech Corp.
www.semtech.com
POWER MANAGEMENT
SC4508
Electrical Characteristics
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S
n
Unless specified: V
DD
= 2.7V to 15V , T
A
= T
J
= -40C to 125C
Note:
(1) This device is ESD sensitive. Use of standard ESD handling precautions is required.
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