TNY253/254/255
D5
FR201
L2
T1
3.3 μH
+ 5.2 V
1
2
10
5
C5
220 μF
25 V
C6
220 μF
16 V
C4
2200 pF
R2
100 kΩ
1 W
D1
1N4005
D2
1N4005
RTN
D6
1N4937
R8
820 Ω
D
EN
BP
TinySwitch
U1
TNY254P
U2
LTV817
R7
100 Ω
C1
6.8 μF
400 V
C2
4.7 μF
400 V
S
85 - 265
VAC
RF1
10 Ω
R9
47 Ω
R3
22 Ω
Fusible
Q1
2N3904
VR1
1N5230B
4.7 V
C3
0.1 μF
R1
1.2 kΩ
R5
18 Ω
1/8 W
D3
1N4005
D4
1N4005
L1
560 μH
R4
1 Ω
1 W
R6
0.82 Ω
1/2 W
C8
2.2 nF
Y1 Safety
PI-2244-082898
Figure 11. 3.6 W Constant Voltage-Constant Current Cellular Phone Charger Circuit.
D3
1N3934
T1
1
+ 9 V
10
6
C6
100 μF
16V
D1
1N4004
VR1
1N5239B
5
RTN
C2
2.2 μF
200 V
C1
2.2 μF
200 V
D
S
115 VAC
15ꢀ
EN
BP
TinySwitch
U1
TNY253P
C4
68 pF
1 KV
C3
0.1 μF
C5
D2
1N4004
2.2 nF
R2
100 Ω
RF1
1.8 Ω
Y1 Safety
Fusible
PI-2190-031501
Figure 12. 0.5 W Open Loop AC Adapter Circuit.
Figureꢀ11ꢀshowsꢀaꢀ5.2ꢀV,ꢀ3.6ꢀWꢀcellularꢀphoneꢀchargerꢀcircuitꢀ
thatꢀusesꢀtheTNY254ꢀandꢀprovidesꢀconstantꢀvoltageꢀandꢀconstantꢀ
capacitorꢀC4ꢀandꢀresistorꢀR2ꢀcompriseꢀtheꢀclampꢀcircuitꢀthatꢀ
limitsꢀtheꢀturn-offꢀvoltageꢀspikeꢀonꢀtheꢀTinySwitchꢀDRAINꢀpinꢀ
toꢀaꢀsafeꢀvalue.ꢀꢀTheꢀsecondaryꢀwindingꢀisꢀrectifiedꢀandꢀfilteredꢀ
byꢀD5ꢀandꢀC5ꢀtoꢀprovideꢀtheꢀ5.2ꢀVꢀoutput.ꢀꢀAdditionalꢀfilteringꢀ
isꢀprovidedꢀbyꢀL2ꢀandꢀC6.ꢀꢀTheꢀoutputꢀvoltageꢀisꢀdeterminedꢀ
byꢀtheꢀsumꢀofꢀtheꢀoptocouplerꢀU2ꢀꢀLEDꢀforwardꢀdropꢀ(~ꢀ1ꢀV)ꢀ
andꢀZenerꢀdiodeꢀVR1ꢀvoltage.ꢀꢀTheꢀresistorꢀR8,ꢀmaintainsꢀaꢀ
biasꢀcurrentꢀthroughꢀtheꢀZenerꢀtoꢀimproveꢀitsꢀvoltageꢀtolerance.ꢀ
currentꢀoutputꢀoverꢀanꢀuniversalꢀinputꢀ(85ꢀtoꢀ265ꢀVAC)ꢀrange.ꢀ
TheꢀACꢀinputꢀisꢀrectifiedꢀandꢀfilteredꢀbyꢀD1ꢀ-ꢀD4,ꢀC1ꢀandꢀC2ꢀ
toꢀcreateꢀaꢀhigh-voltageꢀDCꢀbusꢀconnectedꢀtoꢀT1ꢀinꢀseriesꢀwithꢀ
theꢀhigh-voltageꢀMOSFETꢀinsideꢀtheꢀTNY254.ꢀꢀTheꢀinductorꢀ
L1ꢀformsꢀaꢀπ-filterꢀinꢀconjunctionꢀwithꢀC1ꢀandꢀC2.ꢀꢀTheꢀresistorꢀ
R1ꢀdampsꢀresonancesꢀinꢀtheꢀinductorꢀL1.ꢀꢀTheꢀlowꢀfrequencyꢀofꢀ
operationꢀofꢀTNY254ꢀ(44ꢀkHz)ꢀallowsꢀuseꢀofꢀtheꢀsimpleꢀπ-filterꢀ
describedꢀaboveꢀinꢀcombinationꢀwithꢀaꢀsingleꢀꢀY1-capacitorꢀC8ꢀ
toꢀmeetꢀworldwideꢀconductedꢀEMIꢀstandards.ꢀꢀTheꢀdiodeꢀD6,ꢀ
AꢀsimpleꢀconstantꢀcurrentꢀcircuitꢀisꢀimplementedꢀusingꢀtheꢀVBEꢀ
ofꢀtransistorꢀQ1ꢀtoꢀsenseꢀtheꢀvoltageꢀacrossꢀtheꢀcurrentꢀsenseꢀ
resistorꢀR4,ꢀwhichꢀcanꢀbeꢀmadeꢀupꢀofꢀoneꢀorꢀmoreꢀresistorsꢀtoꢀ
Rev E
02/12
7
POWERINT [ Power Integrations ]
