© Semiconductor Components Industries, LLC, 2006

October, 2006 − Rev. 4

1

Publication Order Number:

NCP1378/D

NCP1378

PWM Current−Mode

Controller for Free−Running

Quasi−Resonant Operation

The NCP1378 combines a true current mode modulator and

a demagnetization detector to ensure full borderline/critical

Conduction Mode in any load/line conditions and minimum drain

voltage switching (Quasi−Resonant operation). Due to its inherent

skip cycle capability, the controller enters burst mode as soon as the

power demand falls below a predetermined level. As this happens at

low peak current, no audible noise can be heard. An internal 8.0

ms

timer prevents the free−run frequency to exceed 100 kHz (therefore

below the 150 kHz CISPR−22 EMI starting limit), while the skip

adjustment capability lets the user select the frequency at which the

burst foldback takes place.

The transformer core reset detection is done through an auxiliary

winding which, brought via a dedicated pin, also enables fast Over

Voltage Protection (OVP). Once an OVP has been detected, the IC

permanently latches off.

The NCP1378 also features an efficient protective circuitry that, in

presence of an overcurrent condition, disables the output pulses and

enters a safe burst mode, trying to restart. Once the default has gone,

the device auto−recovers. Finally an internal 1.0 ms Soft−Start

eliminates the traditional startup stress.

The NCP1378 is tailored for low voltage applications having

UVLO thresholds of 8.4 V (on) and 7.5 V (off).

Features

Typical Applications

*For additional information on our Pb−Free strategy and soldering details, please

download the ON Semiconductor Soldering and Mounting Techniques Reference

Manual, SOLDERRM/D.

SOIC−8

D SUFFIX

CASE 751

PIN CONNECTIONS

Device

Package

ORDERING INFORMATION

NCP1378DR2

SOIC−8

2500 Tape & Reel

MARKING

DIAGRAMS

1

8

PDIP−7

P SUFFIX

CASE 626B

1

Dmg

8 HV

2

FB

3

CS

4

GND

5 Drv

(Top View)

NCP1378P

PDIP−7

50 Units/Rail

1378P

AWL

YYWWG

1

†For information on tape and reel specifications,

including part orientation and tape sizes, please

refer to our Tape and Reel Packaging Specifications

Brochure, BRD8011/D.

NCP1378PG

PDIP−7

(Pb−Free)

50 Units/Rail

http://onsemi.com

A

= Assembly Location

L, WL

= Wafer Lot

Y, YY

= Year

W, WW = Work Week

G or G

= Pb−Free Package

NCP1378DR2G

SOIC−8

(Pb−Free)

2500 Tape & Reel

1

8

1378

ALYW

G

1

8