200W ATX PC Power Supply

Thanks to Pavel Ruzicka for his permission to publish this article on this site. Author: Pavel Ruzicka

Email: pavouk@comp.cz

Web: http://pavouk.comp.cz

Here I bring you wiring diagram of PCs power supply of DTK company. This power

supply has ATX design and 200W performance. I was drawed diagram, when I

repaired this power supply.

This power supply circuit uses chip TL494. Similar circuit is used in the most power

supplies with output power about 200W.Device use push-pull transistor circuit with

regulation of output voltage.

Line

vol

tage

goe

s th

roug

h in

put f

ilter

circ

uit (

C1,

R1,

T1,

C4,

T5)

to th

e br

idge

rect

ifier

. Whe

n vo

ltage

is s

witc

hed

from

230V

to 1

15V,

then

rect

ifier

wor

ks li

ke a

dou

bler

. Var

isto

rs Z

1 an

d Z2

hav

e ov

ervo

ltage

pro

tect

func

tion

on th

e lin

e in

put.

Ther

mis

tor N

TCR

1 lim

its in

put c

urre

nt u

ntil

capa

cito

rs C

5 an

d C

6 ar

e ch

arge

d. R

2 an

d R

3 ar

e on

ly fo

r dis

char

ge

capa

cito

rs a

fter d

isco

nnec

ting

pow

er s

uppl

y. W

hen

pow

er s

uppl

y is

con

nect

ed to

the

line

volta

ge, t

hen

at fi

rst a

re c

harg

ed

capa

cito

rs C

5 an

d C

6 to

geth

er fo

r abo

ut 3

00V.

Then

take

a ru

n se

cond

ary

pow

er s

uppl

y co

ntro

lled

by tr

ansi

stor

Q12

and

on

his

outp

ut w

ill be

vol

tage

. Beh

ind

the

volta

ge

regu

lato

r IC

3 w

ill be

vol

tage

5V,

whi

ch g

oes

in to

the

mot

herb

oard

and

it is

nec

essa

ry fo

r tur

n-on

logi

c an

d fo

r "W

ake

on

som

ethi

ng" f

unct

ions

.

Nex

t uns

tabi

lized

vol

tage

goe

s th

roug

h di

ode

D30

to th

e m

ain

cont

rol c

hip

IC1

and

cont

rol t

rans

isto

rs Q

3 an

d Q

4. W

hen

mai

n po

wer

sup

ply

is ru

nnin

g, th

en th

is v

olta

ge g

oes

from

+12

V ou

tput

thro

ugh

diod

e D

.

Stan

d-B

y m

ode

In s

tand

-by

mod

e is

mai

n po

wer

sup

ply

bloc

ked

by p

ositi

ve v

olta

ge o

n th

e PS

-ON

pin

thro

ugh

resi

stor

R23

from

seco

ndar

y po

wer

sup

ply.

Bec

ause

of t

his

volta

ge is

ope

ned

trans

isto

r Q10

, whi

ch o

pens

Q1,

whi

ch a

pplie

s re

fere

nce

volta

ge +

5V fr

om p

in 1

4 IO

1 to

pin

4 IO

1. S

witc

hed

circ

uit i

s to

tally

blo

cked

. Tra

nzis

tors

Q3

and

Q4

are

both

ope

ned

and

shor

t-circ

uit w

indi

ng o

f aux

iliary

tran

sfor

mer

T2.

Due

to s

hort-

circ

uit i

s no

vol

tage

on

the

pow

er c

ircui

t. By

vol

tage

on

pin

4

we

can

driv

e m

axim

um p

ulse

-wid

th o

n th

e IO

1 ou

tput

. Zer

o vo

ltage

mea

ns th

e hi

ghes

t pul

se-w

idth

. +5V

mea

ns th

at p

ulse

disa

ppea

r.

Now

we

can

expl

ain

func

tion

of ru

nnin

g po

wer

sup

ply.

Som

ebod

y pu

shes

the

pow

er b

utto

n on

com

pute

r. M

othe

boar

d lo

gic

put t

o gr

ound

inpu

t pin

PS-

ON

. Tra

nsis

tor Q

10 c

lose

s

and

next

Q1

clos

es. C

apac

itor C

15 b

egin

s hi

s ch

argi

ng th

roug

h R

15 a

nd o

n th

e pi

n 4

IC1

begi

ns d

ecre

ase

volta

ge to

zer

o

than

ks to

R17

. Due

to th

is v

olta

ge is

max

imum

pul

se-w

idth

con

tinuo

sly

incr

ease

d an

d m

ain

pow

er s

uppl

y sm

ooth

ly g

oes

run.

In a

nor

mal

ope

ratio

n is

pow

er s

uppl

y co

ntro

lled

by IC

1. W

hen

trans

isto

rs Q

1 an

d Q

2 ar

e cl

osed

, the

n Q

3 an

d Q

4 ar

e

open

ed. W

hen

we

wan

t to

open

one

from

pow

er tr

ansi

stor

s (Q

1, Q

2), t

hen

we

have

to c

lose

his

exc

iting

tran

sist

or (Q

3,

Q4)

. Cur

rent

goe

s vi

a R

46 a

nd D

14 a

nd o

ne w

indi

ng T

2. T

his

curre

nt e

xcite

vol

tage

on

base

of p

ower

tran

sist

or a

nd d

ue

to p

ositi

ve fe

edba

ck tr

ansi

stor

goe

s qu

ickl

y to

sat

urat

ion.

Whe

n th

e im

puls

e is

fini

shed

, the

n bo

th e

xciti

ng tr

ansi

stor

s go

es

to o

pen.

Pos

itive

feed

back

dis

sape

ars

and

over

shoo

t on

the

exci

ting

win

ding

qui

ckly

clo

ses

pow

er tr

ansi

stor

. Afte

r it i

s

proc

ess

repe

tead

with

sec

ond

trans

isto

r. Tr

ansi

stor

s Q

1 an

d Q

2 al

tern

atel

y co

nnec

ts o

ne e

nd o

f prim

ary

win

ding

to

posi

tive

or n

egat

ive

volta

ge. P

ower

bra

nch

goes

from

em

itor o

f Q1

(col

lect

or Q

2) th

roug

h th

e th

ird w

indi

ng o

f exc

iting

trans

form

er T

2. N

ext t

hrou

g pr

imar

y w

indi

ng o

f mai

n tra

nsfo

rmer

T3

and

capa

cito

r C7

to th

e vi

rtual

cen

ter o

f sup

ply

volta

ge.

Out

put v

olta

ge s

tabi

lisat

ion

Out

put v

olta

ges

+5V

and

+12V

are

mea

sure

d by

R25

and

R26

and

thei

r out

put g

oes

to th

e IC

1. O

ther

vol

tage

s ar

e no

t

stab

ilised

and

they

are

just

ified

by

win

ding

num

ber a

nd d

iode

pol

arity

. On

the

outp

ut is

nec

essa

ry re

acta

nce

coil

due

to

high

freq

uenc

y in

terfe

renc

e.

This

vol

tage

is ra

ted

from

vol

tage

bef

ore

coil,

pul

se-w

idth

and

dur

atio

n cy

cle.

On

the

outp

ut b

ehin

d th

e re

ctifi

er d

iode

s is

a

com

mon

coi

l for

all

volta

ges.

Whe

n w

e ke

ep d

irect

ion

of w

indi

ngs

and

win

ding

num

ber c

orre

spon

ding

to o

utpu

t vol

tage

s,

then

coi

l wor

ks li

ke a

tran

sfor

mer

and

we

have

com

pens

atio

n fo

r irre

gula

r loa

d of

indi

vidu

al v

olta

ges.

In a

com

mon

pra

ctis

e ar

e vo

ltage

dev

iatio

ns to

10%

from

rate

d va

lue.

Fro

m th

e in

tern

al 5

-V re

fere

nce

regu

lato

r (pi

n 14

IC1)

goe

s re

fere

nce

volta

ge th

roug

h th

e vo

ltage

div

ider

R24

/R19

to in

verti

ng in

put(p

in 2

) of e

rror a

mpl

ifier

. Fro

m th

e

outp

ut o

f pow

er s

uppl

y co

mes

vol

tage

thro

ugh

divi

der R

25,R

26/R

20,R

21 to

the

non

inve

rting

inpu

t (pi

n 1)

. Fee

dbac

k C

1,

R18

pro

vide

s st

abilit

y of

regu

lato

r. Vo

ltage

from

erro

r am

plifi

er is

com

pare

d to

the

ram

p vo

ltage

acr

oss

capa

cito

r C11

.

Whe

n th

e ou

tput

vol

tage

is d

ecre

ased

, the

n vo

ltage

on

the

erro

r am

plifi

er is

tood

ecre

ased

. Exc

iting

pul

se is

long

er, p

ower

trans

isto

rs Q

1 an

d Q

2 ar

e lo

nger

ope

ned,

wid

th o

f pul

se b

efor

e ou

tput

coi

l is

grat

er a

nd o

utpu

t pow

er is

incr

ease

d. T

he

seco

nd e

rror a

mpl

ifier

is b

lock

ed b

y vo

ltage

on

the

pin

15 IC

1.

Pow

erG

ood

Mai

nboa

rd n

eeds

"Pow

erG

ood"

sig

nal.

Whe

n al

l out

put v

olta

ges

goes

to s

tabl

e, th

en P

ower

Goo

d si

gnal

goe

s to

+5V

(logi

cal o

ne).

Pow

erG

ood

sign

al is

usu

ally

con

nect

ed to

the

RES

ET s

igna

l.

+3.3

V Vo

ltage

sta

bilis

atio

n

Look

at c

ircui

t con

nect

ed to

out

put v

olta

ge +

3.3V

. Thi

s ci

rcui

t mak

es a

dditi

onal

volta

ge s

tabi

lisat

ion

due

to lo

ss o

f vol

tage

on c

able

s. T

here

are

one

aux

iliary

wire

from

con

nect

or fo

r mea

sure

3.3

V vo

ltage

on

mot

herb

oard

. Nex

t goe

s to

the

curre

nt

regu

lato

r ZIC

1, w

hich

ope

ns Q

13.

For e

xam

ple

whe

n vo

ltage

incr

ease

s (s

mal

l loa

d), t

rans

isto

r Q13

is m

ore

open

ed a

nd n

egat

ive

puls

es a

cros

s D

32

decr

ease

s ou

tput

vol

tage

.

Ove

rvol

tage

circ

uit

This

circ

uit i

s co

mpo

sed

from

Q5,

Q6

and

man

y di

scre

te c

ompo

nent

s. C

ircui

t gua

rds

all o

f out

put v

olta

ges

and

whe

n th

e

som

e lim

it is

exc

eede

d, p

ower

sup

ply

is s

topp

ed.

For e

xam

ple

whe

n I b

y m

ista

ke s

hort-

circ

uit -

5V w

ith +

5V, t

hen

posi

tive

volta

ge g

oes

acro

ss D

10, R

28, D

9 to

the

base

Q6.

This

tran

sist

or is

now

ope

ned

and

open

s Q

5. +

5V fr

om p

in 1

4 IC

1 co

mes

acr

oss

diod

e D

11 to

the

pin

4 IC

1 an

d po

wer

supp

ly is

blo

cked

. Bey

ond

that

goe

s vo

ltage

aga

in to

bas

e Q

6. P

ower

sup

ply

is s

till b

lock

ed, u

ntil

he is

dis

conn

ecte

d fro

m

pow

er li

ne in

put.

ATX

Mot

herb

oard

Pow

er

AT

X po

wer

con

nect

or o

n th

e m

othe

rboa

rd c

onsi

sts

of tw

o ro

w o

f pin

s.

This

con

nect

or fr

om th

e AT

X po

wer

sup

ply

can

only

be

fitte

d in

one

way

.

Color

Pin

Name

Description

1

+3.3

V

Pow

er +

3.3V

2 +3

.3V

Po

wer

+3.

3V

3

GN

D

Gro

und

4

+5V

V

cc +

5V

5

GN

D

Gro

und

6

+5V

V

cc +

5V

7

GN

D

Gro

und

8

PWR

OK

Pow

er G

ood

9

5VSB

+5

V S

tand

by

10

+1

2V

Pow

er +

12V

11

+3.3

V

Pow

er +

3.3V

12

-12V

Po

wer

-12V

13

GN

D

Gro

und

14

PS

-ON

R

emot

e Po

wer

ON

/OFF

15

G

ND

G

roun

d

16

GN

D

Gro

und

17

G

ND

G

roun

d

18

-5V

Po

wer

-5V

19

+5V

V

cc +

5V

20

+5

V

Vcc

+5V

AT P

C P

ower

Sup

ply

1

Ref

eren

ce a

nd S

ourc

es:

• Th

is sc

hem

atic

has

bee

n su

bmitt

ed b

y Zs

olt S

ebes

tyen

AT P

C P

ower

Sup

ply

2

Ref

eren

ce a

nd S

ourc

es:

• Th

is sc

hem

atic

has

bee

n su

bmitt

ed b

y Zs

olt S

ebes

tyen

AT P

C P

ower

Sup

ply

3

Ref

eren

ce a

nd S

ourc

es:

• Th

is sc

hem

atic

has

bee

n su

bmitt

ed b

y Zs

olt S

ebes

tyen

AT P

C P

ower

Sup

ply

4

Ref

eren

ce a

nd S

ourc

es:

• Th

is sc

hem

atic

has

bee

n su

bmitt

ed b

y Zs

olt S

ebes

tyen

AT P

C P

ower

Sup

ply

5

Ref

eren

ce a

nd S

ourc

es:

• Th

is sc

hem

atic

has

bee

n su

bmitt

ed b

y Zs

olt S

ebes

tyen

Oth

er v

alue

s no

t ind

icat

ed o

n sc

hem

atic

are

:

• R

31 =

1 K

Ohm

•

R35

= 1

00 K

Ohm

•

R40

= 3

.3 K

Ohm

•

R34

= 1

00 K

Ohm

•

R36

= 3

.3 K

Ohm

•

R39

= 8

.2 K

Ohm

•

R43

= 2

.2 K

Ohm

•

R25

= 1

KO

hm

• R

20 =

3.9

KO

hm

• R

37 =

2.2

KO

hm

• R

55 =

56

KO

hm

• R

26 =

2.2

KO

hm

• R

27 =

2.2

KO

hm

• R

28 =

1.2

KO

hm

• R

29 =

910

Ohm

•

R13

= 4

.2 K

Ohm

•

R24

= 2

.2 K

Ohm

•

R11

= 3

.3 K

Ohm

•

R12

= 3

.3 K

Ohm

•

R41

= 5

10 O

hm

• V

R1

= 2

KO

hm

• C

18 =

4.7

uF

•

C20

= 1

0 uF

•

C12

= 2

.2 u

F

• C

10 =

1 u

F

• C

13 =

4.7

uF

AT Motherboard Power

(At the Computer)

2x MOLEX 15-48-0106 CONNECTOR at the Computer.

2x MOLEX 90331-0001 CONNECTOR at the Powersupply cables.

P8

Pin Name Color Description

1 PG Orange Power Good, +5 VDC when all voltages has stabilized. 2 +5V Red +5 VDC (or n/c) 3 +12V Yellow +12 VDC 4 -12V Blue -12 VDC 5 GND Black Ground 6 GND Black Ground

P9

Pin Name Color Description

1 GND Black Ground 2 GND Black Ground 3 -5V White or Yellow -5 VDC 4 +5V Red +5 VDC 5 +5V Red +5 VDC 6 +5V Red +5 VDC Note: Pins part number is 08-50-0276, Product specification is PS-90331.