TNY253/254/255

7

Rev E

02/12

Figure 11. 3.6 W Constant Voltage-Constant Current Cellular Phone Charger Circuit.

Figure11showsa5.2V,3.6Wcellularphonechargercircuit

thatusestheTNY254andprovidesconstantvoltageandconstant

currentoutputoveranuniversalinput(85to265VAC)range.

TheACinputisrectifiedandfilteredbyD1-D4,C1andC2

tocreateahigh-voltageDCbusconnectedtoT1inserieswith

thehigh-voltageMOSFETinsidetheTNY254.Theinductor

L1formsaπ-filterinconjunctionwithC1andC2.Theresistor

R1dampsresonancesintheinductorL1.Thelowfrequencyof

operationofTNY254(44kHz)allowsuseofthesimpleπ-filter

describedaboveincombinationwithasingleY1-capacitorC8

tomeetworldwideconductedEMIstandards.ThediodeD6,

capacitorC4andresistorR2comprisetheclampcircuitthat

limitstheturn-offvoltagespikeontheTinySwitchDRAINpin

toasafevalue.Thesecondarywindingisrectifiedandfiltered

byD5andC5toprovidethe5.2Voutput.Additionalfiltering

isprovidedbyL2andC6.Theoutputvoltageisdetermined

bythesumoftheoptocouplerU2LEDforwarddrop(~1V)

andZenerdiodeVR1voltage.TheresistorR8,maintainsa

biascurrentthroughtheZenertoimproveitsvoltagetolerance.

AsimpleconstantcurrentcircuitisimplementedusingtheV

oftransistorQ1tosensethevoltageacrossthecurrentsense

resistorR4,whichcanbemadeupofoneormoreresistorsto

Figure 12. 0.5 W Open Loop AC Adapter Circuit.

PI-2244-082898

TinySwitch

D

S

EN

BP

+ 5.2 V

RTN

D1

1N4005

C1

6.8 F

400 V

Fusible

RF1

10

C3

0.1 F

85 - 265

VAC

L1

560 H

D2

1N4005

D3

1N4005

D4

1N4005

R2

100 k

1 W

U2

LTV817

D5

FR201

L2

3.3 H

C5

220 F

25 V

C2

4.7 F

400 V

C6

220 F

16 V

R7

100

R3

22

R4

1

1 W

R9

47

Q1

2N3904

R8

820

VR1

1N5230B

4.7 V

C8

2.2 nF

Y1 Safety

U1

TNY254P

C4

2200 pF

D6

1N4937

R6

0.82

1/2 W

T1

R1

1.2 k

1

2

5

10

R5

18

1/8 W

PI-2190-031501

TinySwitch

D

S

EN

BP

+ 9 V

RTN

D1

1N4004

C1

2.2 F

200 V

Fusible

RF1

1.8

C4

68 pF

1 KV

115 VAC

± 15%

R2

100

D2

1N4004

C3

0.1 F

D3

1N3934

C6

100 F

16V

C2

2.2 F

200 V

VR1

1N5239B

C5

2.2 nF

Y1 Safety

U1

TNY253P

T1

1

5

6

10