© 2008 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN4800A/C, FAN4801/1S/2/2L • Rev. 1.0.1

7

Pin Configuration

Figure 6. Pin Configuration (Top View

)

Pin Definitions

Pin #

Name

Description

1

IEA

Output of PFC Current Amplifier.

The signal from this pin is compared with an internal

sawtooth to determine the pulse width for PFC gate drive.

2

IAC

Input AC Current.

For normal operation, this input provides current reference for the multiplier.

The suggested maximum IAC is 100µA.

3

ISENSE

PFC Current Sense.

The non-inverting input of the PFC current amplifier and the output of

multiplier and PFC ILIMIT comparator.

4

VRMS

Line-Voltage Detection.

Line voltage detection. The pin is used for PFC multiplier.

5

SS

PWM Soft-Start.

During startup, the SS pin charges an external capacitor with a 10µA

constant current source. The voltage on FBPWM is clamped by SS during startup. In the event

of a protection condition occurring and/or PWM disabled, the SS pin is quickly discharged.

6

FBPWM

PWM Feedback Input.

The control input for voltage-loop feedback of PWM stage.

7

RT/CT

Oscillator RC Timing Connection.

8

RAMP

PWM RAMP Input.

In current mode, this pin functions as the current sense input; when in

voltage mode, it is the feed forward sense input from PFC output 380V (feedforward ramp).

9

ILIMIT

Peak Current Limit Setting for PWM.

The peak current limits setting for PWM.

10

GND

Ground.

11

OPWM

PWM Gate Drive.

The totem-pole output drive for PWM MOSFET. This pin is internally

clamped under 15V to protect the MOSFET.

12

OPFC

PFC Gate Drive.

The totem pole output drive for PWM MOSFET. This pin is internally clamped

under 15V to protect the MOSFET.

13

VDD

Supply.

The power supply pin. The threshold voltages for startup and turn-off are 11V and

9.3V, respectively. The operating current is lower than 10mA.

14

VREF

Reference Voltage.

Buffered output for the internal 7.5V reference.

15

FBPFC

Voltage Feedback Input for PFC.

The feedback input for PFC voltage loop. The inverting

input of PFC error amplifier. This pin is connected to the PFC output through a divider network.

16

VEA

Output of PFC Voltage Amplifier.

The error amplifier output for PFC voltage feedback loop.

A compensation network is connected between this pin and ground.