TD1509 has large output voltage ripple

ena

TD1509 has large output voltage ripple [Copy link]

Currently, there is a board using TD1509-P5, the output current is about 30ma, the inductor is 47uh/1a, and the output capacitor is a 100uF high-frequency electrolytic capacitor. However, in actual operation, the output voltage will have a ripple of 0.2V, and the ripple will become larger during high and low temperature tests. I don't know what the reason is. The inductance calculated according to the manual is also correct, and the inductance is basically unchanged in actual tests, but I don't know how to calculate the capacity of the high-frequency electrolytic capacitor at the output?

qwqwqw2088

During high and low temperature tests, the ripple will become larger.

Problems with electrolytic capacitors, factors related to ESR

At low temperatures, the ripple is larger

ena

qwqwqw2088 posted on 2019-11-19 21:20 When testing at high and low temperatures, the ripple will become larger. The problem with electrolytic capacitors is that the ripple is larger at low temperatures due to the ESR factor.

How is the value of the output electrolytic capacitor calculated at normal temperature? I don't quite understand

qwqwqw2088

ena posted on 2019-11-19 23:58 At normal temperature, how is the value of the output electrolytic capacitor calculated? I don't quite understand

You can find some in the download center

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tomjianchun.xu

At low temperatures (-20 to -40 degrees), the ESR of electrolytic capacitors will become very large, more than 10 times that of normal temperature, so it is normal for the ripple to become larger at low temperatures. Sometimes, even at low temperatures, oscillation will occur.