NCP1255

http://onsemi.com

2

Figure 1. Typical Application Example

Eris

Vbulk

.

.

ramp

comp.

OPP

Vout

OVP

.

1

2

3

4

5

8

6

7

Eris

BO

NCP1255

Table 1. PIN FUNCTION DESCRIPTION

Pin No.

Pin Name

Function

Pin Description

1

OPP/OVP

Adjust the Over Power Protection.

Latches off the part

A resistive divider from the auxiliary winding to this pin sets the

OPP compensation level. When brought above 3 V, the part is fully

latched off.

2

FB

Feedback pin

Hooking an optocoupler collector to this pin will allow regulation.

3

CS

Current sense + ramp

compensation

This pin monitors the primary peak current but also offers a means

to introduce ramp compensation.

4

GND

−

The controller ground.

5

DRV

Driver output

The driver’s output to an external MOSFET gate.

6

Supplies the controller

This pin is connected to an external auxiliary voltage and supplies

the controller. When above a certain level, the part fully latches off.

7

BO

Brown−Out input

A voltage below the programmed level stops the controller. When

above, the controller can start.

8

Timer

Sets the timer duration

A 22−kW resistor sets the duration to 200 ms. When shorted to

ground or made open, this pin limits the internal current and fixes

the timer duration.

Table 2. ORDERING INFORMATION AND OPTIONS

Controller

Frequency

OCP Latched

OCP Auto−Recovery

Package

NCP1255AD65R2G

65 kHz

Yes

No

0.6

SOIC−8

(Pb−Free)

2500 / Tape

& Reel

NCP1255BD65R2G

65 kHz

No

Yes

0.6

NCP1255CD65R2G

65 kHz

Yes

No

0.7

NCP1255DD65R2G

65 kHz

No

Yes

0.7

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specification Brochure, BRD8011/D.