HA16174P/FP

Rev.1.00 Jan 06, 2006 page 19 of 36

4-2. Operation on a Momentary Outage

(PFC operation hold on momentary outage: PFC hold function)

(1) When the Momentary Outage is Short

During a momentary outage, the voltage on the PFC-ON pin is discharged. When it reaches 1.6 V, charging of the

capacitor on the DELAY pin starts. The voltage on the PFC-ON pin continues to fall and, when it reaches 1.4 V,

source current begins to flow through the pin. The lower the PFC-ON voltage, the greater the amount of current, so

the PFC-ON pin voltage does not fall below the level determined by the external resistor and the source current.

AC-voltage input is resumed, if the DELAY pin voltage doesn’t reach 1.25 V before the PFC-On pin voltage rises

above 1.75 V, the PFC output voltage resumes quickly. In this case, the soft-start function does not operate.

Full-wave rectified AC

PFC-ON

DELAY

OUT

PF output voltage

Ipfc-on

1.6 V

1.75 V

1.25 V

Figure 6 PFC Hold Function Operation Waveform 1

The hold time for PFC operation is adjusted by the value of the capacitance on the DELAY pin. Note, however, that

if VCC voltage of IC is not normally supplied during a momentary outage, the PFC-ON hold function does not

operate.