How to eliminate the voltage drop of the diode?

sky999

How to eliminate the voltage drop of the diode? [Copy link]

VIN is the charger input, BT2 is the backup battery, that is, when the power is off, the battery is used for power supply. However, due to the diode, the battery is always not fully charged in this circuit. How to eliminate the voltage drop of the diode? The battery is 12.6V when fully charged, and the charger is also

maychang

"How do you eliminate the voltage drop across a diode?"

The first method: Use a Schottky diode for D5. The forward voltage drop of a Schottky diode is smaller than that of an ordinary silicon diode.

The second method is to replace D5 with a P-channel MOS tube, and replace the gate of the P-channel MOS tube of D5 with a low-power N-channel MOS tube or a low-power NPN transistor. This method uses more components and is more expensive.

sky999

maychang posted on 2019-10-20 10:34 "How to eliminate the voltage drop of the diode?" The first method: D5 uses a Schottky diode. The forward voltage drop of the Schottky diode is higher than that of the ordinary...

OK, thanks

伟林电源

Is it possible to consider increasing the voltage of the charger to offset the voltage drop of the diode?

qwqwqw2088

The voltage drop of the diode cannot be cancelled by itself.

It can only be done according to needs, such as increasing the charging voltage as mentioned above, or changing the circuit structure instead of replacing the diode with a MOS.

leifengfirst

You can also consider ideal diodes

曹伟1993

You can replace it with a MOS tube. Theoretically, there is no voltage on it, but that is an ideal state. Even if it passes through the wire, there will be a voltage drop, so it is better to increase the charging voltage. Generally, it is charged at 12.6V, and the battery is 12V.

qiushenghua

Aren't you afraid of it exploding when charging like this?

sky999

qiushenghua posted on 2019-10-21 19:13 Aren’t you afraid of explosion if you charge it like this?

Why did it explode?