TNY253/254/255
+
1
T1
D1
1N4934
10
L1
15
µH
C4
330
µF
10 V
C5
47
µF
10 V
+ 7.5 V
4
8
RTN
Optional
DC IN
120-375 VDC
C1
0.01
µF
1 kV
R1
100
Ω
1/2 W
D
TinySwitch
EN
BP
U1
TNY253P
S
U2
SFH615-2
R2
1 kΩ
C2
56 pF
1 kV
C3
0.1
µF
VR1
1N5235B
–
C6
680 pF
Y1 Safety
PI-2246-082898
Figure 9. 1.3 W TV Stand-by Circuit using TNY253.
D2
SB540
10
1
T1
L1
10
µH
C4
2700
µF
6.3 V
C5
220
µF
10 V
R1
150 kΩ
1W
C2
4700 pF
1 kV
D1
1N4937
4
8
+5V
RTN
Optional
D
TinySwitch
EN
BP
240-375
VDC
C1
0.01
µF
1 kV
U1
TNY255P
S
U2
LTV817
R2
68
Ω
C3
0.1
µF
VR1
1N5229B
PI-2242-082898
Figure 10. 10 W PC Stand-by Supply Circuit.
PC Standby
The TNY255 was designed specifically for applications such as
PC standby, which require up to 10W of power from 230VAC
or 100/115VAC with doubler circuit. The TNY255 operates at
130kHz as opposed to 44kHz for TNY253/254. The higher
frequency operation allows the use of a low cost EE16 core
transformer up to the 10W level. Figure10 shows a 5V, 10W
circuit for such an application. The circuit operates from the
high voltage DC supply already available from the main power
supply. Capacitor C1 filters the high voltage DC supply, and is
necessary only if there is a long trace length from the source of
the DC supply to the inputs of the PC standby circuit. The high
voltage DC bus is applied to the primary winding of T1 in series
with the integrated high voltage MOSFET inside the TNY255.
The diode D1, capacitor C2 and resistor R1 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 D2 and C4 to provide the 5V ouput. Additional
filtering is provided by L1 and C5. The output voltage is
determined by the sum of the optocoupler U2 LED forward
drop (~ 1V) and Zener diode VR1 voltage. The resistor R2,
maintains a bias current through the Zener to improve its
voltage tolerance.
Cellular Phone Charger
The
TinySwitch
is well suited for applications that require a
6
C
7/01
POWERINT [ POWER INTEGRATIONS, INC. ]
