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TNY274P 参数 Datasheet PDF下载

TNY274P图片预览
型号: TNY274P
PDF下载: 下载PDF文件 查看货源
内容描述: 高能效,离线式开关具有更大的灵活性和扩展功率范围 [Energy Efficient, Off-Line Switcher with Enhanced Flexibility and Extended Power Range]
分类和应用: 开关
文件页数/大小: 24 页 / 1604 K
品牌: POWERINT [ Power Integrations ]
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TNY274-280  
C5  
2.2 nF  
250 VAC  
L2  
D7  
Ferrite Bead  
3.5 × 7.6 mm  
VR1  
BYV28-200  
T1  
+12 V, 1 A  
P6KE150A  
NC  
8
6
J3  
J4  
C11  
100 µF  
25 V  
C10  
1000 µF  
25 V  
D1  
1N4007  
F1  
D2  
R2  
1
3
1N4007  
100 Ω  
RTN  
C4  
10 nF  
1 kV  
3.15 A  
J1  
R1  
C1  
6.8 µF  
400 V  
C2  
22 µF  
400 V  
1 kΩ  
R7  
20 Ω  
4
85-265  
VAC  
RV1  
275 VAC  
D5  
1N4007GP  
2
5
D6  
UF4003  
R5*  
3.6 MΩ  
J2  
D3  
1N4007  
D4  
1N4007  
VR2  
1N5255B  
28 V  
L1  
1 mH  
C6  
VR3  
BZX79-C11  
11 V  
1 µF  
60 V  
R3  
47 Ω  
1/8 W  
*R5 and R8 are optional  
components  
R6  
390 Ω  
1/8 W  
R8*  
21 kΩ  
1%  
C7 is configurable to adjust  
U1 current limit, see circuit  
description  
U2  
PC817A  
D
EN/UV  
BP/M  
S
S
R4  
2 kΩ  
1/8 W  
C7 †  
100 nF  
50 V  
TinySwitch-III  
U1  
TNY278P  
PI-4244-021406  
Figure 14. TNY278P, 12 V, 1 A Universal Input Power Supply.  
LED forward drop, current will flow in the optocoupler LED.  
This will cause the transistor of the optocoupler to sink current.  
When this current exceeds the ENABLE pin threshold current  
the next switching cycle is inhibited. When the output voltage  
fallsbelowthefeedbackthreshold,aconductioncycleisallowed  
to occur and, by adjusting the number of enabled cycles, output  
regulation is maintained. As the load reduces, the number of  
enabled cycles decreases, lowering the effective switching  
frequencyandscalingswitchinglosseswithload. Thisprovides  
almost constant efficiency down to very light loads, ideal for  
meeting energy efficiency requirements.  
Applications Example  
The circuit shown in Figure 14 is a low cost, high efficiency,  
flyback power supply designed for 12 V, 1 A output from  
universal input using the TNY278.  
The supply features under-voltage lockout, primary sensed  
output overvoltage latching shutdown protection, high  
efficiency (>80%), and very low no-load consumption  
(<50mWat265VAC). Outputregulationisaccomplishedusing  
a simple zener reference and optocoupler feedback.  
The rectified and filtered input voltage is applied to the primary  
winding of T1. The other side of the transformer primary is  
driven by the integrated MOSFET in U1. Diode D5, C2, R1,  
R2, and VR1 comprise the clamp circuit, limiting the leakage  
inductance turn-off voltage spike on the DRAIN pin to a safe  
value. The use of a combination a Zener clamp and parallel  
RC optimizes both EMI and energy efficiency. Resistor R2  
allows the use of a slow recovery, low cost, rectifier diode by  
limiting the reverse current through D5. The selection of a  
slow diode also improves efficiency and conducted EMI but  
should be a glass passivated type, with a specified recovery  
time of 2 µs.  
As the TinySwitch-III devices are completely self-powered,  
there is no requirement for an auxiliary or bias winding on the  
transformer. However by adding a bias winding, the output  
overvoltage protection feature can be configured, protecting  
the load against open feedback loop faults.  
When an overvoltage condition occurs, such that bias voltage  
exceeds the sum ofVR2 and the BYPASS/MULTIFUNCTION  
(BP/M) pinvoltage(28V+5.85V),currentbeginstoowintothe  
BP/Mpin. Whenthiscurrentexceeds5mAtheinternallatching  
shutdown circuit in TinySwitch-III is activated. This condition  
is reset when the BP/M pin voltage drops below 2.6 V after  
removal of the AC input. In the example shown, on opening  
the loop, the OVP trips at an output of 17 V.  
The output voltage is regulated by the Zener diode VR3. When  
theoutputvoltageexceedsthesumoftheZenerandoptocoupler  
E
2/06  
8