PQ1PF1 データシートの表示（PDF） - Sharp Electronics

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PQ1PF1

Primary Regulator for Switching Power Supply (50W Class)

Sharp Electronics 

Primary Regulators

4. FB-terminal

Fig.6 shows circuit example of feedback signal input circuit for fixed output voltage.

Fig.6

VCC

GND 2 5

1 VDS

PQ1PF1

43

FB

VCA

R

+

C

PC1

+

PC1

PQ1PF1

Output voltage is controlled by connecting photocoupler PC1 between FB-terminal and GND terminal . When output voltage or

transmisslon waveform is unstable, connect C&R on both sides of PC1 to reduce gain of control system.

5. Overcurrent detection circuit

This module detects drain current ID of MOS-FET, and minimize output pulse width by pulse-by-pulse at ID=2.5A TYP.

6. Overheat protection circuit

Overheat protection circuit starts to operate when internal temperature of IC is at 140˚C TYP. CA voltage VCA will be released from

clamped voltage 3.6V and the capacitor CA which is connected to CA terminal will be charged again by 10µA of charge current.

When VCA increases to 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 required. Output shut-down condition is

maintained even if lowering internal temperature of IC. To restart, Vcc needs to be lowered less than 9.3V by applying input voltage

again.

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