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BD7692FJ-E2

Power Factor Correction Controller IC

ROHM Semiconductor 

BD7692FJ

3 About ErrAMP - continued

3.4 VS Overvoltage Gain Increase Function (DOVP)

When output voltage rises by startup or a rapid change of the output load, output voltage rises for a long term because a

voltage control loop is slow. The VS pin voltage becomes VOVP (2.625 V Typ) (equivalent to +5 % of output voltage), the

error amplifier increases the speed of the voltage control loop. By this operation, it reduces ON width of OUT and

prevents a long-term rise of the output voltage. When the VS pin voltage decreases under VOVP (2.625 V Typ), this

operation stops.

3.5 VS Overvoltage Protection Function (SOVP)

IC has static OVP for the time when VS is above the overvoltage gain increase function voltage VOVP.

The VS pin voltage rises from VOVP1 (2.725 V Typ), it stops switching immediately. The VS pin voltage less than VOVP2

(2.600 V Typ), it starts switching. Figure 5 shows the operation.

PFC

Output

VOVP1

VOVP2

VS

OUT

Switching

Stop

Figure 5. VS Overvoltage Protection Operation

3.6 Over Voltage Reduce Function at Start Up (OVR)

When the VS pin voltage performs a rise in startup to VGUP (2.250 V Typ) (equivalent to -10 % of output voltage), it

discharges the EO voltage to the off threshold voltage forcibly. OUT pulse width is narrows when the EO voltage falls,

through rate of output voltage becomes slow and reduces over voltage in the startup.

This function is effective only once after VCCUVLO cancellation.

4 OVP Pin Over Voltage Protection

The OVP pin is an overvoltage protection function to use when VS feedback circuit is above static OVP (cf. Figure 6) at the

time of abnormality. When the OVP pin voltage rises over VOVP3 (2.7 V Typ), it stops switching operation after tOVP3 (60 µs

Typ) (cf. Figure 7). If the OVP pin becomes VOVP4 (2.6 V Typ) or less, it restarts operation.

PFC-OUT

OVP

OVP

VOVP3

OUT

2.7V/2.6V

Driver

Logic

Figure 6. OVP Over Voltage Protection

OUT

tOVP3

Figure 7. Timing Chart

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TSZ22111 • 15 • 001

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TSZ02201-0F2F0A200320-1-2

04.Oct.2018 Rev.001

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