STEVAL-ISA126V1

5 V-2 A, 115 kHz flyback with temporary extra-power

management based on the VIPER28HN

Data brief

Features

•

•

Output Voltage: 5 V

•

•

•

Precision of output regulation: ΔV

•

High Frequency output Voltage ripple:

ΔV

•

Max ambient operating temperature: TA 60

ºC

•

800 V avalanche rugged power section

•

PWM operation , at 115 kHz with frequency

jittering for lower EMI

•

Limiting current with adjustable set point

•

On-board soft-start

•

Safe auto-restart after a fault condition, low

stand-by power (< 50 mW at 265 Vac)

•

Adjustable and accurate over voltage

protection, thermal shutdown with

hysteresis, delayed overload protection

•

RoHS compliant

Description

This document describes a 5 V-2 A application

with 3.3 A peak current capability for 1.9 sec,

using VIPer28H, a new off-line high voltage

converter from STMicroelectronics.

In some applications an SMPS, normally

supposed to deliver a certain amount of power,

from time to time undergoes load peaks that can

be even two or more times as much, but only for

a time interval which is short if compared to the

thermal time constants of the power components.

Typical examples of such loads are printers and

audio systems.

In these cases, it is more cost-effective to

thermally design the system for the maximum

continuous power and not for the peak power

demand, which will be sustained only for a limited

time window.

Such a design is possible thanks to the EPT

function of VIPER28H, which allows the designer

to fix the maximum time window during which the

converter is able to manage the peak power still

maintaining output voltage regulation. If the

overload lasts more than this time window, the

converter is automatically shut down in auto-

restart mode, in order to avoid the damaging of

the power components.

December 2013

DocID025423 Rev 1

1/4

For further information contact your local STMicroelectronics sales

office

www.st.com