SC4808A Datasheet, PDF (1/31 Pages) Semtech Corporation – 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.
Typical Application Circuit
SC4808A/B
High Performance Dual
Ended PWM Controller
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
Vo
Vin
Gnd_Out
Gnd_In
RSENSE
Revision October 20, 2005
OUTA RC
OUTB REF
CS
SYNC
VCC
SYNC ^FB
LUVLO GND
SC4808
1
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