STSR3
SYNCHRONOUS RECTIFIERS SMART DRIVER FOR FLYBACK
s s
s s s
s
SUPPLY VOLTAGE RANGE: 4V TO 5.5V TYPICAL PEAK OUTPU...
STSR3
SYNCHRONOUS RECTIFIERS SMART DRIVER FOR FLYBACK
s s
s s s
s
SUPPLY
VOLTAGE RANGE: 4V TO 5.5V TYPICAL PEAK OUTPUT CURRENT: (SOURCE 2A, SINK 3.5A) OPERATING FREQUENCY: 30 TO 750 KHz SMART TURN-OFF ANTICIPATION TIMING AUTOMATIC TURN OFF FOR DUTY CYCLE LESS THAN 14% POSSIBILITY TO OPERATE IN DISCONTINUOUS MODE
SO-8
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DESCRIPTION STSR3 Smart Driver IC provides a high current outputs to properly drive secondary Power
Mosfets used as Synchronous Rectifier in low output
voltage, high efficiency Flyback Converters. From a synchronizing clock input, withdrawn on the secondary side of the isolation transformer, the IC generates a driving signal with set dead times with respect to the primary side PWM signal. The IC operation prevents secondary side shoot-through conditions at turn-on of the primary
switch providing anticipation in turn-off the output. This smart function is implemented by a fast cycle-after-cycle logic control mechanism, based on a high frequency oscillator synchronized by the clock signal. This anticipation is externally set through external component. A special Inhibit function allows to shut-off the drive output. This feature makes discontinuous conduction mode possible and avoids reverse conduction of the synchronous rectifier.
SCHEMATIC DIAGRAM
Vcc
2
+
BIAS UVLO
5.7V
CK 4
PEAK DETECTOR
ANTICIPATION SET
3 SETANT
+
HIGH FREQUENCY OSCILLATOR
DIGITAL CONTROL
OUTPUT BUFFER
+
7 OUTGATE
INHIBIT 5
+ 25mV
1 N/C
6
8
SGLGND
PW...