High Performance Dual
Ended PWM Controller
POWER MANAGEMENT
Description
The SC4808A/B is a dual-ended, high frequency, integrated
PWM controller, optimized for isolated applications that
require minimum space. It can be configured for current
or voltage mode operation with required control circuitry
where secondary side error amplifier is used.
Some of the key features are high frequency operation of
1 MHz that allows the use of smaller components thus
saving cost and valuable board space. An internal ramp
on the Current Sense pin allows Internal Slope
Compensation programmed by an external resistor. Other
features include programmable frequency up to 1MHz,
Pulse by Pulse current and Line Monitoring Input with
Hysteresis to reduce stress on the power components.
A unique oscillator is used to synchronize two SC4808’s to
work out of phase. This minimizes the input and output
ripple thus reducing noise on the output line and reducing
stress and size of input/output filter components. The dual
outputs can be configured in Push-Pull, Half Bridge and
Full Bridge format with programmable dead time between
two outputs depending on the size of the timing
components.
The SC4808 also features a turn on threshold of 12V for
SC4808A and 4.4V for SC4808B. They are available in
MSOP-10 packages.
SC4808A/B
Features
120µA starting current
Pulse by pulse current limit
Programmable operation up to 1MHz
Internal soft start
Programmable line undervoltage lockout
Over current shutdown
Dual output drive stages on push-pull configuration
Programmable internal slope compensation
Programmable mode of operation (peak current mode
or voltage mode)
External frequency synchronization
Bi-phase mode of operation
-40 to 105 °C operating temperature
10 Pin MSOP lead free package available. WEEE and
RoHS compliant.
Applications
Telecom equipment and power supplies
Networking power supplies
Industrial power supplies
Push-pull converter
Half bridge converter
Full bridge converter
Isolated VRM’s
Typical Application Circuit
Vo
Vin
Gnd_Out
RSENSE
Gnd_In
OUTA
OUTB
CS
VCC
SYNC
RC
REF
SYNC
FB
LUVLO GND
SC4808
Revision October 20, 2005
1
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