Simple, Synchronous
Voltage Mode PWM Controller
POWER MANAGEMENT
Description
The SC2608A 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 SC2608A
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.
SC2608A 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 SC2608A operates at a fixed frequency of 250kHz
providing an optimum compromise between efficiency ,
external component size, and cost.
SC2608A has a thermal protection circuit, which is
activated if the junction temperature exceeds 150
O
C.
SC2608A
Features
+5V or +12V input voltage
250kHz operation
High efficiency (>90%)
1.5% Reference voltage accuracy
Hiccup mode over current protection
Robust output drive
R
DS(ON)
Current sensing for protection
Industrial temperature range
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
SC2608
SC2608A
sense
COMP/SS SENSE
+12V/+5V/+3.3V
+12V
GND
VCC
DL
PHASE
DH
BST
VOUT
sense
Figure 1
Revision 2: April, 2006
1
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