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发表于 2012-12-6 13:19:35
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可以参考下 LM2596 的电路。
这是手册上给出的解释。
Additional diodes are required in this regulator configuration.
Diode D1 is used to isolate input voltage ripple or noise from
coupling through the CIN capacitor to the output, under light
or no load conditions. Also, this diode isolation changes the
topology to closley resemble a buck configuration thus providing
good closed loop stability. A Schottky diode is recommended
for low input voltages, (because of its lower voltage
drop) but for higher input voltages, a fast recovery diode
could be used.
Without diode D3, when the input voltage is first applied, the
charging current of CIN can pull the output positive by several
volts for a short period of time. Adding D3 prevents the
output from going positive by more than a diode voltage.
加一个 二极管可能会好些。 |
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