Abstract

The VIPer12A is an integrated PWM and MOSFET

circuit for low power application in the 5W range,

typically in Cellular Phone Adapters. It is housed in

surface mount SO-8 and DIP8 packages.

With the availability of VIPer12A in SO-8 package

and the limited number of external components for

a real PWM operation, building a compact and

performant power supply becomes simple.

The travel adaptor design presented here, has

been made with the aim of minimising overall cost

for a secondary voltage and current regulated

adapter, topology widely used in Cellular Phone

Adapters.

The VIPer12A presents itself as the answer for

lower consumption in standby, like in home

appliances where it will be required to limit non

negligible off the use consumptions, as

recommended by the “European Commission of

Energy”. Today regulations demand less than 1

Watt. Thanks to VIPer12A low power consumption,

it is possible to achieve 100mW standby power in

a wide range of operations.

1.0 PRINCIPLE OF OPERATION

The circuit is a standard Flyback converter with

secondary current and voltage regulation driving

the VIPer12A feedback pin through an

optocoupler.

1.1 The VIPer12A

1.1.1 Start-up phase

VIPer12A, as any member of the VIPer family, has

an integrated high voltage current source to charge

C3 Vdd capacitor until it reaches its startup level

(15V). When Vdd gets to 15V, the VIPer switches,

supplied by the energy stored in C3, until it is

supplied through the auxiliary winding.

1.1.2 Auxiliary Supply

VIPer12A has a wide operating voltage range from

9V to 40V, respectively maximum and minimum

values for undervoltage and overvoltage

protections. This wide voltage supply range

simplifies the design of the VIPer12A supply but, to

ensure proper operation of the application in any

case, it is advised:

- in normal operation, to supply VIPer12A within its

operating range;

- in standby mode, to minimize auxiliary

consumption to achieve very low standby power;

- in short circuit, to limit output power by going into

an hiccup mode;

- in constant current mode, to ensure current

regulation below 2V before going into hiccup

mode.

VIPER12A属于集成电路（IC） > AC DC 转换器，离线开关。意法半导体（ST）集团制造生产的VIPER12AAC DC 转换器，离线开关该系列是元器件级控制产品，用于构建将交流市电转换为直流电（通常电压大幅降低）的设备。集成和未集成系统主要开关元件的器件均包括在内。由于高输入输出电压比，以及此类系统中通常需要隔离，这些器件通常与外部变压器配合使用。尽管通常使用定制变压器来实现此用途，但也有许多专门用于此用途的库存产品，请参见“开关转换器，SMPS 变压器”标题。