NCP1207A(2004) 查看數據表（PDF） - ON Semiconductor

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NCP1207A
(Rev.:2004)

PWM Current-Mode Controller for Free Running Quasi-Resonant Operation

ON Semiconductor 

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

short−circuit trip point is not dependent upon any VCC auxiliary level.

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

• Free−Running Borderline/Critical Mode Quasi−Resonant Operation

• Current−Mode with Adjustable Skip−Cycle Capability

• No Auxiliary Winding VCC Operation

• Auto−Recovery Overcurrent Protection

• Latching Overvoltage Protection

• External Latch Triggering, e.g. Via Overtemperature Signal

• 500 mA Peak Current Source/Sink Capability

• Undervoltage Lockout for VCC Below 10 V

• Internal 1.0 ms Soft−Start

• Internal 8.0 ms Minimum TOFF

• Adjustable Skip Level

• Internal Temperature Shutdown

• Direct Optocoupler Connection

• SPICE Models Available for TRANsient Analysis

• Pb−Free Package is Available

Typical Applications

• AC/DC Adapters for Notebooks, etc.

• Offline Battery Chargers

• Consumer Electronics (DVD Players, Set−Top Boxes, TVs, etc.)

• Auxiliary Power Supplies (USB, Appliances, TVs, etc.)

http://onsemi.com

8

1

8

1

MARKING

DIAGRAMS

8

SO−8

D1, D2 SUFFIX

CASE 751

1207A

ALYW

1

8

PDIP−8

N SUFFIX

CASE 626

1

1207AP

AWL

YYWW

1207A/P = Device Code

A

= Assembly Location

WL, L = Wafer Lot

YY, Y = Year

WW, W = Work Week

PIN CONNECTIONS

Dmg 1

FB 2

CS 3

Gnd 4

8 HV

7 NC

6 VCC

5 Drv

(Top View)

ORDERING INFORMATION

Device

Package

Shipping†

NCP1207ADR2 SOIC−8 2500/Tape & Reel

NCP1207ADR2G

NCP1207AP

SOIC−8

(Pb−Free)

PDIP−8

2500/Tape & Reel

50 Units/Tube

†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.

© Semiconductor Components Industries, LLC, 2004

1

November, 2004 − Rev. 1

Publication Order Number:

NCP1207A/D

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