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NCP1254

Current-Mode PWM Controller for Off-line Power Supplies featuring Peak Power Excursion

ON Semiconductor 

NCP1254

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Current-Mode PWM

Controller for Off-line

Power Supplies featuring

Peak Power Excursion

The NCP1254 is a highly integrated PWM controller capable of

delivering a rugged and high performance offline power supply in a

TSOP−6 package. With a supply range up to 35 V, the controller hosts

a jittered 65−kHz switching circuitry operated in peak current mode

control. When the power on the secondary side starts to decrease, the

controller automatically folds back its switching frequency down to a

minimum level of 26 kHz. As the power further goes down, the part

enters skip cycle while freezing the peak current setpoint.

To help building rugged converters, the controller features several

key protective features: a non−dissipative Over Power Protection for a

constant maximum output current regardless of the input voltage, two

latched over voltage protection inputs − either through a dedicated pin

or via the Vcc input and a dual−level auto−recovery/latched overload/

short−circuit timer.

The controller architecture is designed to authorize a transient peak

power excursion when the current setpoint hits the limit. At this point,

the switching frequency is increased from 65 kHz to 130 kHz until the

peak event disappears. The timer duration is then modulated as the

converter crosses a peak power excursion mode (long) or undergoes a

short circuit (short).

Features

• 65−kHz Fixed−frequency Current−mode Control Operation with

130−kHz Excursion

• Internal and Adjustable Over Power Protection (OPP) Circuit

• Frequency Foldback down to 26 kHz and Skip−cycle in Light Load

Conditions

• Adjustable Slope Compensation

• Internally Fixed 4−ms Soft−start

• Fixed Timer−based Auto−recovery Overload/Short−circuit Protection

• 100% to 25% Timer Reduction from Overload to Short−circuit Fault

• Double Vcc Hiccup for a Reduced Average Power in Fault Mode

• Frequency Jittering in Normal and Frequency Foldback Modes

• Latched OVP Input for Improved Robustness and Latched OVP on Vcc

• Up to 35−V Vcc Maximum Rating

• Extremely Low No−load Standby Power

• This is a Pb−Free Device

Typical Applications

• Converters requiring peak−power capability such as printers power

supplies, ac−dc adapters for game stations.

This document contains information on a product under development. ON Semiconductor

reserves the right to change or discontinue this product without notice.

http://onsemi.com

1

TSOP−6

CASE 318G

STYLE 13

MARKING DIAGRAM

54xAYWG

G

1

54

= Specific Device Code

x

= A or B

A

= Assembly Location

Y

= Year

W

= Work Week

G

= Pb−Free Package

(Note: Microdot may be in either location)

PIN CONNECTIONS

GND 1

6 DRV

FB 2

OPP/Latch 3

5 VCC

4 CS

(Top View)

ORDERING INFORMATION

See detailed ordering and shipping information in the package

dimensions section on page 2 of this data sheet.

© Semiconductor Components Industries, LLC, 2013

1

March, 2013 − Rev. P1

Publication Order Number:

NCP1254/D

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