R2A20111SP/DD

REJ03F0231-0100 Rev.1.00 Mar 28, 2007

Page 4 of 40

(1) Setting the PFC function hold time for momentary outage

When the PFC-ON pin is driven below 0.79 V (typ.) due to a momentary outage, the delay pin functions as source

current. PFC operation continues until the capacitor is charged to 1.2 V (typ.). After the voltage on the delay pin

reaches 1.2 V (typ.), the pin functions as sink current, and PFC operation terminates. The PFC function hold time

can be set by the value of the external capacitor.

(2) Shutdown

When this pin is pulled up to 4 V (typ.) or higher, the IC enters the shutdown state. Accordingly, the VREF signal

becomes low and the operating current becomes several hundred

μA. The IC does not resume operation until Vcc

falls to 4 V (max.) or below.

CGND Pin:

This pin is the non-inverting input to the current amplifier.

CAI Pin:

This pin is the inverting input to the current amplifier and functions as source current for PFC control. AC current is

controlled to be proportional to the source current and the power factor is corrected.

VREF Pin:

Temperature-compensated voltage with an accuracy of 5 V ± 3% is output from this pin. The pin should supply no

more than 5 mA (max.) source current. This pin has no sink capabilities.

CAO Pin:

This pin is the current amplifier output, and is connected to the phase-compensation circuit of the current amplifier.

The result of comparison of the voltage on this pin and the CT pin produces the pulse output from the OUT pin. The

pulse is limited when the voltage on the CAO pin rises.

CLIMIT Pin:

This pin is for detecting overcurrent. When the voltage on this pin drops to 1.3 V (typ.) or below, OUT pin is stopped.

RT Pin:

This pin is for frequency adjustment of the oscillator and connected to GND via resistor. The IC operating frequency is

determined by this resistance value and the CT pin capacitance value.

Additionally, this resistance value determines the maximum current on the CAI pin and the current on the DELAY pin.

CT Pin:

This pin is for frequency adjustment of the oscillator and connected to GND via capacitor. The IC operating frequency

is determined by this capacitance value and the resistance value of the RT pin.

PFC-ON Pin:

This pin is applied smoothing voltage of rectified AC voltage and detects the input AC voltage level. When 0.82 V

(typ.) or more is applied to this pin, PFC operation starts. When the voltage is 0.79 V (typ.) or lower, the PFC operation

stops after the PFC operation hold time (refer to the description of DELAY pin operation).

IAC Pin:

This pin is for detecting waveform of the input AC voltage.

FB Pin:

This pin is the input to the voltage amplifier. This pin is applied to voltage divided PFC output with resistors. The

feedback loop is intended to keep 2.5 V (typ.).

When output voltage rises up and the voltage of this pin is higher than 2.688 V (typ.) or more, the OUT pin is stopped.

Moreover, when this voltage of this pin is 0.52 V (typ.) or lower, the OUT pin is also stopped. These functions detect

overvoltage, low voltage, and feedback-loop disconnection.