SC4808B-1 Datasheet, PDF (1/28 Pages) Semtech Corporation – High Performance Dual Ended PWM Controller

SC4808B-1
High Performance Dual
Ended PWM Controller
POWER MANAGEMENT
Description
The SC4808B-1 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 SC4808B-
1’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 SC4808B-1 also features a turn on threshold of 4.4V
and is available in MSOP-10 package.
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
‹ MSOP-10 lead free package. This product is fully 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
Gnd_In
RSENSE
Revision: January 11, 2006
OUTA RC
OUTB REF
CS
SYNC
VCC
SYNC ^FB
LUVLO GND
SC4808
1
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