NCP1560

http://onsemi.com

4

PIN DESCRIPTION

Pin

Name

Application Information

1

This pin is connected to the bulk DC input voltage supply. A constant current source supplies current from

range is 21.5 V to 150 V.

2

UV/OV

Input supply voltage is scaled down and sampled by means of a resistor divider. The supply voltage must

be scaled down between 1.52 V and 3.61 V within the specified input voltage range.

3

NC

Not Connected.

4

FF

varying the feedforward ramp amplitude in proportion to the input voltage, changes in loop bandwidth are

eliminated.

5

CS

Over current sense input. If the CS voltage exceeds 0.48 V or 0.57 V, the converter enters the

Cycle−by−Cycle or Cycle Skip current limit mode, respectively.

6

The capacitor connected between this pin and ground sets the Cycle Skip period. A soft−start sequence

follows at the conclusion of the fault period.

7

A single external resistor between this pin and GND sets the oscillator fixed frequency.

8

An external resistor between this pin and GND sets the voltage on the Max DC Comparator inverting

input. The duty cycle is limited by comparing the voltage on the Max DC Comparator inverting input to the

Feedforward Ramp.

9

SS

An internal 6.2 mA current source charges the external capacitor connected to this pin. The duty cycle is

limited during startup by comparing the voltage on this pin to the Oscillator Ramp.

10

The error signal from an external error amplifier is fed into this input and compared to the Feedforward

Ramp. A series diode and resistor offset the voltage on this pin before it is applied to the PWM

Comparator inverting input.

11

Precision 5.0 V reference output. Maximum output current is 6.0 mA.

12

transitions.

13

OUT2

Output of the PWM controller with leading and trailing edge overlap delay. OUT2 can be used to drive a

synchronous rectifier topology, an active clamp/reset switch, or both.

14

GND

Control circuit ground.

15

OUT1

Main output of the PWM controller.

16

Positive input supply voltage. This pin is connected to an external capacitor for energy storage. An

to the IC via this pin, by means of an auxiliary winding.