Samsung D61B Training Manual page 60

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Circuit Operation Description
6)Chopper Circuit (12Vamp, 12-18V)
[Function Description]
The oscillation of the primary IC8301 (STR-F6267) provides the voltage to the secondary coil (Pins 15 and 16).
Constant voltage regulation for the secondary side is controlled by the Chopper Regulator IC8001 (SI-8050S).
[Protection Features]
-Over Voltage Protection
The Latch circuit is activated by the IC8301 (STR-6267) to stop the circuit when the Vcc terminal voltage exceeds
the OVP activating voltage Vcc(OVP)=28V(TYP).
-Over Current Protection
IC8301 (STR-F6267) has a pulse by pulse over-current protection circuit which detects the peak value of the drain
current of the FET per every pulse.
The detection resistors R8301 & RX8301 convert the current to voltage and Pin 2 of the STR-F6267 detects it.
When this value exceeds the set point, the FET cuts OFF to cut out the current and is released to ON by the next
cycle.
Repeating OFF and ON results in the current limit.
IC8001 (SI-8050S) has a built-in over-current protection circuit which is activated around 3.1A.
-Overload Protection
IC8301 (STR-F6267) performs UVLO (Under Voltage Lockout) during the overload status (the drain current is
limited by OCP behavior) caused by a malfunction of the loading side.
This feature protects the IC in case of overload to the secondary side.
-Overheating Protection
For overheating protection, the latch circuit is activated when the temperature of the chip IC8301 (STR-F6267)
exceeds 140℃.
The actual temperature detection is done by the control circuit element.
IC8001 (SI-8050S) employs a built-in overheat protection.
Samsung Electronics
6-21

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