Simple, Synchronous
Voltage Mode PWM Controller
POWER MANAGEMENT
Draft
Description
The SC2608B is a versatile voltage-mode PWM control-
ler designed for use in step down DC/DC power supply
applications. A simple, fixed frequency, highly efficient
buck regulator can be implemented using the SC2608B
with minimal external components. The input voltage
range is from +5V to +12V. Internal level shift and drive
circuitry eliminates the need for an expensive P-channel,
high-side MOSFET. The small device footprint allows for
compact circuit design.
SC2608B features include temperature compensated
voltage reference, triangle wave oscillator, current limit
comparator, and an externally compensated error ampli-
fier. Current limit is implemented by sensing the voltage
drop across the bottom MOSFET R
DS(ON)
.
The SC2608B operates at a fixed frequency of 250kHz
providing an optimum compromise between efficiency ,
external component size, and cost.
SC2608B has a thermal protection circuit, which is
activated if the junction temperature exceeds 150
O
C.
SC2608B
Features
+5V or +12V input voltage
250kHz operation
High efficiency (>90%)
1.25% Voltage feedback accuracy over tempera-
ture
Hiccup mode over current protection
1.2A output drive
R
DS(ON)
Current sensing for protection
Industrial temperature range
Available in SO-8 package
Integrated boot strap diode
Thermal Shut down
Fully WEEE and RoHS Compliant
Applications
Termination supplies
Low cost microprocessor supplies
Peripheral card supplies
Industrial power supplies
High density DC/DC conversion
Typical Application Circuit
Figure 1
Revision 4: Jan. 2007
1
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