AS2214

Primary Side PWM Controller

ASTEC Semiconductor

86

Pin Function Description

Pin Number

Function

Description

Positive supply voltage for the IC.

Output of 5V series regulator.

3

COMP

This pin is the error amplifier output. Typically used to provide loop compensation to

Inverting input of the error amplifier. The non-inverting input is a trimmed 2.5 V

bandgap reference.

5

ISNS

A voltage proportional to inductor current is connected to this pin. The PWM uses this

information to terminate the gate drive of the output.

6

SS

This pin provides a 6

µA current source to linearly charge an external capacitor. This pin

is compared to the RAMP pin in the soft start comparator, terminating output pulses when

RAMP goes above the SS voltage.

7

RAMP

This pin is a level-shifted and buffered oscillator signal used to provide slope compensa-

tion to the current sense signal. The pin also serves as the non-inverting input of the soft-

start comparator.

8

RT/CT

9

OV

This pin latches SS low when pulled above 2.5 V. The latch can be reset by pulling

OV above 4 V then back to ground.

10

ACP

This pin detects the presence of AC signal and drives LEN high.

11

LEN

This pin must be high to enable starting. The pin can also clear all latches by going low

then high.

12

BOK

This pin monitors the bulk voltage through a resistor divider and, when BOK exceeds

2.5 V, provides a 50

µA current source for hysteresis. When BOK drops below 2.5V, SS

is pulled low and the hysteresis current is turned off. Auto-restart after a brown-out is

possible.

13

GND

Circuit common ground.

14

OUT

This totem pole output is designed to directly drive a power MOSFET switch capable of

sourcing and sinking peak currents up to 1 A.