TNY254 Power Integrations Inc., TNY254 Datasheet - Page 6

• Manufacturer Part Number: TNY254
• Description: TinySwitch Family Energy Efficient/ Low Power Off-line Switchers
• Manufacturer: Power Integrations Inc.

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
Figure 10. 10 W PC Stand-by Supply Circuit.
Figure 9. 1.3 W TV Stand-by Circuit using TNY253.
TNY253/254/255
6
C
7/01
240-375
VDC
120-375 VDC
DC IN
–
+
Optional
0.01 F
1 kV
C1
Optional
0.01 F
1 kV
C1
150 k
1 W
R1
56 pF
100
1 kV
1/2 W
C2
R1
4700 pF
1 kV
C2
TNY255P
TNY253P
1N4937
D1
U1
U1
D
S
D
S
TinySwitch
TinySwitch
1
4
1
4
EN
BP
EN
BP
T1
T1
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
0.1 F
0.1 F
C3
10
10
8
8
C3
1N4934
SB540
Y1 Safety
D1
LTV817
680 pF
D2
U2
C6
2700 F
SFH615-2
1N5235B
6.3 V
C4
VR1
U2
330 F
1 k
15 H
10 V
R2
C4
L1
1N5229B
VR1
10 H
68
L1
R2
47 F
10 V
220 F
C5
10 V
C5
RTN
+ 7.5 V
+ 5 V
RTN
PI-2242-082898
PI-2246-082898