TNY253/254/255
D1
1N4934
10
L1
15 μH
T1
+ 7.5 V
RTN
1
4
+
C5
47 μF
10 V
C4
330 μF
10 V
8
Optional
C1
U2
R1
100 Ω
1/2 W
D
S
DC IN
120 - 375
VDC
SFH615-2
EN
BP
TinySwitch
U1
TNY253P
0.01 μF
1 kV
R2
1 kΩ
C3
0.1 μF
C2
56 pF
1 kV
VR1
1N5235B
–
C6
680 pF
Y1 Safety
PI-2246-082898
Figure 9. 1.3 W TV Standby Circuit using TNY253.
D2
SB540
L1
10 μH
T1
+ 5 V
RTN
1
10
8
R1
150 kΩ
1 W
C4
2700 μF
6.3 V
C2
C5
4700 pF
1 kV
220 μF
10 V
4
D1
1N4937
D
S
EN
BP
Optional
TinySwitch
U1
TNY255P
C1
R2
68 Ω
240 - 375
VDC
U2
LTV817
0.01 μF
1 kV
C3
0.1 μF
VR1
1N5229B
PI-2242-082898
Figure 10. 10 W Standby Supply Circuit.
useꢀofꢀaꢀlowꢀcostꢀEE16ꢀcoreꢀtransformerꢀupꢀtoꢀtheꢀ10ꢀWꢀlevel.ꢀ
Figureꢀ10ꢀshowsꢀaꢀ5ꢀV,ꢀ10ꢀWꢀcircuitꢀforꢀsuchꢀanꢀapplication.ꢀ
Theꢀcircuitꢀoperatesꢀfromꢀtheꢀhigh-voltageꢀDCꢀsupplyꢀalreadyꢀ
availableꢀfromꢀtheꢀmainꢀpowerꢀsupply.ꢀꢀCapacitorꢀC1ꢀfiltersꢀtheꢀ
high-voltageꢀDCꢀsupply,ꢀandꢀisꢀnecessaryꢀonlyꢀifꢀthereꢀisꢀaꢀlongꢀ
traceꢀlengthꢀfromꢀtheꢀsourceꢀofꢀtheꢀDCꢀsupplyꢀtoꢀtheꢀinputsꢀofꢀ
theꢀstandbyꢀcircuit.ꢀꢀTheꢀhigh-voltageꢀDCꢀbusꢀisꢀappliedꢀtoꢀtheꢀ
primaryꢀwindingꢀofꢀT1ꢀinꢀseriesꢀwithꢀtheꢀꢀintegratedꢀhigh-voltageꢀ
MOSFETꢀinsideꢀtheꢀTNY255.ꢀꢀTheꢀdiodeꢀD1,ꢀcapacitorꢀC2ꢀandꢀ
resistorꢀR1ꢀcompriseꢀtheꢀclampꢀcircuitꢀthatꢀlimitsꢀtheꢀturn-offꢀ
voltageꢀspikeꢀonꢀtheꢀTinySwitchꢀDRAINꢀpinꢀtoꢀaꢀsafeꢀvalue.ꢀ
TheꢀsecondaryꢀwindingꢀisꢀrectifiedꢀandꢀfilteredꢀbyꢀD2ꢀandꢀC4ꢀ
toꢀprovideꢀtheꢀ5ꢀVꢀouput.ꢀꢀAdditionalꢀfilteringꢀisꢀprovidedꢀbyꢀ
L1ꢀandꢀC5.ꢀTheꢀoutputꢀvoltageꢀisꢀdeterminedꢀbyꢀtheꢀsumꢀofꢀtheꢀ
optocouplerꢀU2ꢀLEDꢀforwardꢀdropꢀ(~ꢀ1ꢀV)ꢀandꢀZenerꢀdiodeꢀ
VR1ꢀvoltage.ꢀꢀTheꢀresistorꢀR2,ꢀmaintainsꢀaꢀbiasꢀcurrentꢀthroughꢀ
theꢀZenerꢀtoꢀimproveꢀitsꢀvoltageꢀtolerance.ꢀForꢀtighterꢀtolerance,ꢀ
aꢀTL431ꢀprecisionꢀreferenceꢀICꢀfeedbackꢀcircuitꢀmayꢀbeꢀused.
Cellular Phone Charger
TheꢀTinySwitchꢀisꢀwellꢀsuitedꢀforꢀapplicationsꢀthatꢀrequireꢀaꢀ
constantꢀvoltageꢀandꢀconstantꢀcurrentꢀoutput.ꢀꢀTinySwitchꢀisꢀ
alwaysꢀpoweredꢀfromꢀtheꢀinputꢀhigh-voltage,ꢀthereforeꢀitꢀdoesꢀ
notꢀrequireꢀbiasꢀwindingꢀforꢀpower.ꢀꢀConsequently,ꢀitsꢀopera-
tionꢀisꢀnotꢀdependentꢀonꢀtheꢀlevelꢀofꢀtheꢀoutputꢀvoltage.ꢀꢀThisꢀ
allowsꢀforꢀconstantꢀcurrentꢀchargerꢀdesignsꢀthatꢀworkꢀdownꢀtoꢀ
zeroꢀvoltsꢀonꢀtheꢀoutput.ꢀ
Rev E
02/12
6
POWERINT [ Power Integrations ]
