© 2010 Fairchild Semiconductor Corporation

www.fairchildsemi.com

FAN4800AS/CS/01S/02S • Rev. 1.0.1

6

Pin Configuration

Figure 7.

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

. The pin is used for the 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. If a

protection condition occurs and/or PWM is 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 feedforward 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 19V to protect the MOSFET.

12

OPFC

PFC Gate Drive

. The totem-pole output drive for PFC 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.