PQ1PF1 查看數據表（PDF） - Sharp Electronics

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PQ1PF1

Primary Regulator for Switching Power Supply (50W Class)

Sharp Electronics 

Primary Regulators

PQ1PF1

3-3 Overvoltage protection function

Fig.4 shows overvoltage protection circuit. Photocoupler PC2 becomes ON-state when output voltage is in overvoltage condition.

When PC2 is ON-state, current from Vcc via resistor R charges capacitor CA and CA voltage VCA increases. When VCA reaches CA

threshold voltageVCA( OVP) 7.7V, internal constant voltage supply of IC becomes OFF-state and maintain shut-down state. To maintain

output shut-down condition, 0.3mA (Vcc=11V) TYP. is reguired. To restart, Vcc needs to be lowered less than operation stopping

voltage VCC(OFF) 9.3V by applying input voltage again.

Fig.4 Overvoltage Protection Cricuit

R

PC2

CA

5

VCC

3

CA PQ1PF1

3-4 ON/OFF control function

IC operation can be stopped and output voltage can be OFF-state by lowering CA voltage VCA less than 0.6V TYP. Fig.5 shows ON/

OFF control circuit. When transistor Q1 becomes ON-state by external signal and VCA is less than 0.6V, output turns off. Output is

ON-state again by soft start function which is caused by Q1 OFF.

Fig. 5 ON/OFF Control Function

Q1

CA

3

CA

PQ1PF1

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