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TNY287KG 参数 Datasheet PDF下载

TNY287KG图片预览
型号: TNY287KG
PDF下载: 下载PDF文件 查看货源
内容描述: 高能效,离线式开关本着补偿过载功率 [Energy-Efficient, Off-Line Switcher With Line Compensated Overload Power]
分类和应用: 开关
文件页数/大小: 26 页 / 2282 K
品牌: POWERINT [ Power Integrations ]
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TNY284-290  
current limit. Because of its small size, the time to charge this  
capacitor is kept to an absolute minimum, typically 0.6 ms. The  
time to charge will vary in proportion to the BYPASS/MULTI-  
FUNCTION pin capacitor value when selecting different current  
limits. Due to the high bandwidth of the ON/OFF feedback,  
there is no overshoot at the power supply output. When an  
external resistor (4 MW) is connected from the positive DC input  
to the ENABLE/UNDERVOLTAGE pin, the power MOSFET  
switching will be delayed during power-up until the DC line  
voltage exceeds the threshold (100 V). Figures 11 and 12 show  
the power-up timing waveform in applications with and without  
an external resistor (4 MW) connected to the ENABLE/  
UNDERVOLTAGE pin. Under start-up and overload conditions,  
when the conduction time is less than 400 ns, the device  
reduces the switching frequency to maintain control of the peak  
drain current.  
and associated components. Secondly, for battery charger  
applications, the current-voltage characteristic often allows the  
output voltage to fall close to 0 V while still delivering power.  
TinySwitch-4 accomplishes this without a forward bias winding  
and its many associated components. For applications that  
require very low no-load power consumption (ꢀ0 mW), a resistor  
from a bias winding to the BYPASS/MULTI-FUNCTION pin can  
provide the power to the chip. The minimum recommended  
current supplied is 1 mA. The BYPASS/MULTI-FUNCTION pin  
in this case will be clamped at 6.4 V. This method will eliminate  
the power draw from the DRAIN pin, thereby reducing the  
no-load power consumption and improving full-load efficiency.  
Current Limit Operation  
Each switching cycle is terminated when the DRAIN current  
reaches the current limit of the device. Current limit operation  
provides good line ripple rejection and relatively constant power  
delivery independent of input voltage.  
During power-down, when an external resistor is used, the  
power MOSFET will switch for 64 ms after the output loses  
regulation. The power MOSFET will then remain off without any  
glitches since the undervoltage function prohibits restart when  
the line voltage is low.  
BYPASS/MULTI-FUNCTION Pin Capacitor  
The BYPASS/MULTI-FUNCTION pin can use a ceramic  
capacitor as small as 0.1 μF for decoupling the internal power  
supply of the device. A larger capacitor size can be used to  
adjust the current limit. For TNY28ꢀ-290, a 1 μF BYPASS/  
MULTI-FUNCTIONAL pin capacitor will select a lower current  
limit equal to the standard current limit of the next smaller  
device and a 10 μF BYPASS/MULTI-FUNCTIONAL pin capacitor  
will select a higher current limit equal to the standard current  
limit of the next larger device. The higher current limit level of  
the TNY290 is set to 8ꢀ0 mA typical. The TNY284 MOSFET  
does not have the capability for increased current limit so this  
feature is not available in this device.  
Figure 13 illustrates a typical power-down timing waveform.  
Figure 14 illustrates a very slow power-down timing waveform  
as in standby applications. The external resistor (4 MW) is  
connected to the ENABLE/UNDERVOLTAGE pin in this case to  
prevent unwanted restarts.  
No bias winding is needed to provide power to the chip  
because it draws the power directly from the DRAIN pin (see  
Functional Description). This has two main benefits. First, for a  
nominal application, this eliminates the cost of a bias winding  
40  
TNY290  
TNY280  
35  
30  
25  
20  
85 100 115 130 145 160 175 190 205 220 235 250 265  
Input Voltage (VAC)  
Figure 15. Comparison of Maximum Overpower for TinySwitch-4 and  
TinySwitch-III as a Function of Input Voltage (Data Collected from  
RDK-295 20 W Reference Design).  
7
www.powerint.com  
Rev. A 09/12