MR4530 datasheet(36/43 Pages) SHINDENGEN

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Shindengen Electric MFG.CO.,LTD

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6.6.4 OVP latch circuit by secondary side detection using auxiliary coil

C201

L201

C202

C205

D201

+12V

GND

D112

PC1

PS2501

C113

35V

100μF

D1NL20U

0.047μF

Nc2

Nc1

ZD2

15V,B2

PC1

PS2501

470Ω

Ns1

100Ω

Fig. 6.22 OVP circuit using auxiliary coil

(1)

Circuit configuration

This circuit consists of NC2, an auxiliary coil; PC1, a photocoupler for OVP; R1; C1; D1; and ZD2, a zener diode

for secondary output detection.

(2)

Circuit operation

Set the NC2 coil voltage to 22 V (VCC(OVP) x 1.1) or greater. If the output voltage exceeds the zener voltage, as

the F/B pin is opened, the photocoupler will activate. As a result, the NC2 coil voltage is applied to the VCC pin

(Pin 4) of the MR4000 Series, the VCC voltage exceeds 20 V, and the IC is latched and stopped for OVP.

(3)

Precautions

Take steps to ensure the circuit does not exceed 21 V, the absolute maximum rating for the withstand voltage of

the IC. Proceed carefully while referring to the constants of the components in the diagram above.

6. Supplementary design information

MR4530 Datasheet(PDF) 36 Page - Shindengen Electric Mfg.Co.Ltd

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