© Semiconductor Components Industries, LLC, 2004

November, 2004 − Rev. 1

1

Publication Order Number:

NCP1207A/D

NCP1207A

PWM Current−Mode

Controller for Free Running

Quasi−Resonant Operation

The NCP1207A 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 Dynamic Self−Supply (DSS) drastically simplifies the

transformer design in avoiding the use of an auxiliary winding to

supply the NCP1207A. This feature is particularly useful in

applications where the output voltage varies during operation (e.g.

battery chargers). Due to its high−voltage technology, the IC is

directly connected to the high−voltage DC rail. As a result, the

The transformer core reset detection is done through an auxiliary

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

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

IC permanently latches off.

Finally, the continuous feedback signal monitoring implemented

with an overcurrent fault protection circuitry (OCP) makes the final

design rugged and reliable.

Features

OFF

Typical Applications

PDIP−8

N SUFFIX

CASE 626

1

8

1

8

SO−8

D1, D2 SUFFIX

CASE 751

18

5

3

4

(Top View)

Dmg

CS

HV

PIN CONNECTIONS

7

6

2

NC

FB

Gnd

Drv

MARKING

DIAGRAMS

1207A/P = Device Code

A

= Assembly Location

WL, L

= Wafer Lot

YY, Y

= Year

WW, W

= Work Week

1207AP

AWL

YYWW

1

8

Device

Package

ORDERING INFORMATION

NCP1207ADR2

SOIC−8

2500/Tape & Reel

NCP1207AP

PDIP−8

50 Units/Tube

NCP1207ADR2G

SOIC−8

(Pb−Free)

2500/Tape & Reel

†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.

http://onsemi.com

1207A

ALYW

1

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