PR8275
High Voltage Start-Up PWM Controller
Pin Descriptions
PINꢀ NAMEꢀ
FUNCTIONꢀ
Thisꢀpinꢀisꢀtoꢀprogramꢀtheꢀswitchingꢀfrequency.ꢀByꢀconnectingꢀaꢀresistorꢀ
toꢀgroundꢀtoꢀsetꢀtheꢀswitchingꢀfrequency.ꢀ
1ꢀ
RTꢀ
Voltageꢀfeedbackꢀpinꢀ(sameꢀasꢀtheꢀCOMPꢀpinꢀinꢀUC384X),ꢀByꢀconnectingꢀ
aꢀphotoꢁcouplerꢀtoꢀcloseꢀtheꢀcontrolꢀloopꢀandꢀachieveꢀtheꢀregulation.ꢀ
Currentꢀsenseꢀpin,ꢀconnectꢀtoꢀsenseꢀtheꢀMOSFETꢀcurrentꢀ
2ꢀ COMPꢀ
3ꢀ
4ꢀ
5ꢀ
6ꢀ
7ꢀ
CSꢀ
GNDꢀ Groundꢀ
OUTꢀ GateꢀdriveꢀoutputꢀtoꢀdriveꢀtheꢀexternalꢀMOSFETꢀ
VCCꢀ Supplyꢀvoltageꢀpinꢀ
NCꢀ
UnconnectedꢀPinꢀ
Connectꢀthisꢀpinꢀtoꢀpositiveꢀterminalꢀofꢀbulkꢀcapacitorꢀtoꢀprovideꢀtheꢀ
startupꢀcurrentꢀforꢀtheꢀcontroller.ꢀWhenꢀVccꢀvoltageꢀtripsꢀtheꢀUVLO(on),ꢀ
thisꢀHVꢀloopꢀwillꢀbeꢀoffꢀtoꢀsaveꢀtheꢀpowerꢀlossꢀonꢀtheꢀstartupꢀcircuit.ꢀ
8ꢀ
HVꢀ
ꢀ
ꢀ
ꢀ
Fig.2
ꢀ
V1.0
2/10
ETC [ ETC ]
