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本帖最后由 超級狗 于 2013-5-10 08:31 编辑 . W+ O0 h! \& n9 {: [3 S* C
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, \8 s% |& ]6 o7 l. n晚上仔細看了一下芯片資料,才發現這電路是從上面抄來的,而且有清楚的解說。
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Some applications require the regulator to remain off until the input voltage reaches a predetermined voltage. An undervoltage lockout feature applied to a buck regulator is shown in Figure 34, while Figure 35 and Figure 36 applies the same feature to an inverting circuit. The circuit in Figure 35 features a constant threshold voltage for turn on and turn off (zener voltage plus approximately one volt). If hysteresis is needed, the circuit in Figure 36 has a turn ON voltage which is different than the turn OFF voltage. The amount of hysteresis is approximately equal to the value of the output voltage. If zener voltages greater than 25V are used, an additional 47 kΩ resistor is needed from the ON /OFF pin to the ground pin to stay within the 25V maximum limit of the ON /OFF pin.
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以後樓主發貼,真的只要圍觀就好!
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