TNY253/254/255
D5
L2
FR201
3.3 µH
T1
1
2
10
+ 5.2 V
C6
220 µF
16 V
C4
2200 pF
C5
220 µF
25 V
R2
100 kΩ
1 W
RTN
D1
1N4005
5
D2
1N4005
D6
R8
820 Ω
TinySwitch
EN
1N4937
D
U1
TNY254P
U2
BP
R7
100 Ω
LTV817
S
85-265
VAC
C1
C2
RF1
10 Ω
6.8 µF 4.7 µF
400 V 400 V
R9
47 Ω
R3
22 Ω
Q1
2N3904
Fusible
C3
0.1 µF
R1
1.2 kΩ
R5
18 Ω
1/8 W
D3
1N4005
D4
1N4005
VR1
1N5230B
4.7 V
L1
560 µH
R4
1 Ω
1 W
C8
2.2 nF
Y1 Safety
R6
0.82 Ω
1/2 W
PI-2244-082898
Figure 11. 3.6 W Constant Voltage-Constant Current Cellular Phone Charger Circuit.
D3
1N3934
T1
1
10
+ 9 V
C6
100 µF
16V
VR1
1N5239B
D1
1N4004
RTN
6
5
TinySwitch
EN
C1
2.2 µF
200 V
C2
2.2 µF
200 V
D
S
115 VAC
15ꢀ
U1
TNY253P
BP
C4
68 pF
1 KV
C5
2.2 nF
Y1 Safety
C3
0.1 µF
D2
1N4004
R2
100 Ω
RF1
1.8 Ω
Fusible
PI-2190-031501
Figure 12. 0.5 W Open Loop AC Adapter Circuit.
create a high voltage DC bus connected to T1 in series with the
high voltage MOSFET inside the TNY254. The inductor L1
forms a π-filter in conjunction with C1 and C2. The resistor R1
damps resonances in the inductor L1. The low frequency of
operationofTNY254(44kHz)allowsuseofthesimple π-filter
described above in combination with a single Y1-capacitor C8
to meet worldwide conducted EMI standards. The diode D6,
capacitor C4 and resistor R2 comprise the clamp circuit that
limits the turn-off voltage spike on the TinySwitch DRAIN pin
to a safe value. The secondary winding is rectified and filtered
by D5 and C5 to provide the 5.2V output. Additional filtering
constant voltage and constant current output. TinySwitch is
always powered from the input high voltage, therefore it does
notrequirebiaswindingforpower. Consequently, itsoperation
is not dependent on the level of the output voltage. This allows
for constant current charger designs that work down to zero
volts on the output.
Figure11 shows a 5.2V, 3.6W cellular phone charger circuit
thatusestheTNY254andprovidesconstantvoltageandconstant
current output over an universal input (85 to 265VAC) range.
The AC input is rectified and filtered by D1 - D4, C1 and C2 to
C
7
7/01
POWERINT [ Power Integrations ]
