TNY255 POWERINT [Power Integrations, Inc.], TNY255 Datasheet - Page 7

• Manufacturer Part Number: TNY255
• Description: TinySwitch Family Energy Efficient, Low Power Off-line Switchers
• Manufacturer: POWERINT [Power Integrations, Inc.]

Figure 12. 0.5 W Open Loop AC Adapter Circuit.
Figure 11. 3.6 W Constant Voltage-Constant Current Cellular Phone Charger Circuit.
constant voltage and constant current output. TinySwitch is
always powered from the input high voltage, therefore it does
not require bias winding for power. Consequently, its operation
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
that uses the TNY254 and provides constant voltage and constant
current output over an universal input (85 to 265VAC) range.
The AC input is rectified and filtered by D1 - D4, C1 and C2 to
85-265
VAC
1N4005
1N4005
Fusible
115 VAC
10
D3
RF1
D1
± 15%
1N4005
1N4005
D2
D4
Fusible
1.8
RF1
6.8 F
400 V
C1
1N4004
1N4004
D2
D1
2.2 F
200 V
1.2 k
560 H
4.7 F
400 V
C1
R1
C2
L1
100 k
100
1 W
R2
2.2 F
200 V
R2
C2
TNY254P
1N4937
68 pF
1 KV
C4
2200 pF
D6
U1
C4
D
S
TNY253P
TinySwitch
U1
EN
BP
1
2
create a high voltage DC bus connected to T1 in series with the
high voltage MOSFET inside the TNY254. The inductor L1
forms a -filter in conjunction with C1 and C2. The resistor R1
damps resonances in the inductor L1. The low frequency of
operation of TNY254 (44kHz) allows use of the simple -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
T1
D
S
LTV817
0.1 F
C3
U2
TinySwitch
1
5
EN
BP
10
5
FR201
T1
Y1 Safety
D5
0.1 F
2.2 nF
2N3904
C3
C8
10
Q1
6
1N3934
D3
47
R9
Y1 Safety
2.2 nF
C5
100 F
1/8 W
18
16V
22
1 W
220 F
1
C6
R5
R4
R3
25 V
C5
100
R7
0.82
1/2 W
R6
1N5239B
VR1
1N5230B
820
220 F
3.3 H
TNY253/254/255
16 V
4.7 V
R8
VR1
C6
L2
+ 9 V
RTN
PI-2244-082898
PI-2190-031501
7/01
+ 5.2 V
RTN
C
7