tny274 Power Integrations, Inc., tny274 Datasheet - Page 6

• Manufacturer Part Number: tny274
• Description: Energy Ef?cient, Of?ine Switcher With Enhanced Flexibility And Extended Power Range
• Manufacturer: Power Integrations, Inc.

At near maximum load, TinySwitch-III will conduct during
nearly all of its clock cycles (Figure 6). At slightly lower load,
it will “skip” additional cycles in order to maintain voltage
regulation at the power supply output (Figure 7). At medium
loads, cycles will be skipped and the current limit will be reduced
(Figure 8). At very light loads, the current limit will be reduced
even further (Figure 9). Only a small percentage of cycles will
occur to satisfy the power consumption of the power supply.
The response time of the ON/OFF control scheme is very fast
compared to PWM control. This provides tight regulation and
excellent transient response.
200
100
Figure 9. Operation at Very Light Load.
400
200
Figure 10. Power Up with Optional External UV Resistor (4 MΩ)
10
0
5
0
0
6
TNY274-280
V
0
I
CLOCK
D
DRAIN
DRAIN
MAX
V
G
6/06
V
EN
V
V
DC-INPUT
Connected to EN/UV Pin.
DRAIN
BYPASS
Time (ms)
1
PI-2661-072400
2
200
100
200
100
Figure 11. Power Up Without Optional External UV Resistor
200
100
Figure 13. Slow Power Down Timing with Optional External
400
200
400
300
200
100
400
300
200
100
10
Figure 12. Normal Power Down Timing (without UV).
0
5
0
0
0
0
0
0
0
0
0
V
V
V
Connected to EN/UV Pin.
DC-INPUT
(4 MΩ) UV Resistor Connected to EN/UV Pin.
DRAIN
BYPASS
Time (ms)
Time (s)
Time (s)
2.5
.5
1
V
V
V
DC-INPUT
DC-INPUT
V
DRAIN
DRAIN
2
5
1