VIPER12A Ver la hoja de datos (PDF) - STMicroelectronics

Número de pieza

componentes Descripción

Fabricante

VIPER12A

LOW POWER OFF LINE SMPS PRIMARY SWITCHER

STMicroelectronics 

VIPer12ADIP / VIPer12AS

Figure 8 : Rectangular U-I output characteristics for battery charger

F1

AC IN

T2

C3

D4

C4

C5

ISO1

C6

R1

C2

D1

D3

U1

FB

VDD

CONTROL

VIPerX2A

DRAIN

SOURCE

T1

C1

D2

C7

R2

D5

DCOUT

U2

R3

Vcc

R4

Vref

R5

C8

C10

-

+

C9

+

-

GND

R7

R8 TSM101

R10

R6

R9

GND

RECTANGULAR U-I OUTPUT

CHARACTERISTIC

A complete regulation scheme can achieve

combined and accurate output characteristics.

Figure 8 presents a secondary feedback through

an optocoupler driven by a TSM101. This device

offers two operational amplifiers and a voltage

reference, thus allowing the regulation of both

output voltage and current. An integrated OR

function performs the combination of the two

resulting error signals, leading to a dual voltage

and current limitation, known as a rectangular

output characteristic.

This type of power supply is especially useful for

battery chargers where the output is mainly used in

current mode, in order to deliver a defined charging

rate. The accurate voltage regulation is also

convenient for Li-ion batteries which require both

modes of operation.

WIDE RANGE OF VDD VOLTAGE

The VDD pin voltage range extends from 9V to 38V.

This feature offers a great flexibility in design to

achieve various behaviors. In figure 8 a forward

configuration has been chosen to supply the

device with two benefits:

– as soon as the device starts switching, it

immediately receives some energy from the

auxiliary winding. C5 can be therefore reduced

and a small ceramic chip (100 nF) is sufficient to

insure the filtering function. The total start up

time from the switch on of input voltage to output

voltage presence is dramatically decreased.

– the output current characteristic can be

maintained even with very low or zero output

voltage. Since the TSM101 is also supplied in

forward mode, it keeps the current regulation up

whatever the output voltage is.The VDD pin

voltage may vary as much as the input voltage,

that is to say with a ratio of about 4 for a wide

range application.

8/15

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