Share a low-side MOS tube drive circuit

[vbsemi]

https://www.youtube.com/watch?v=CTJ2eVMSQaA

虽然 MOS 是电压驱动的，但栅极和源极之间存在较大的结电容。当它打开时，需要大的充电电流，当它关闭时，需要大的放电电流。因此，需要一个低阻抗的充电和放电路径。

这是一个低侧 MOS 管驱动电路。输入端由 Q3 和外围组成，使用公共基极连接形成一个电平

转换电路。控制输入从 （5） 接收，控制输入可由 MCU 生成。输入 3V 转换为输出 12V。由于 Q1 Q2 是互补发射极跟随器，因此不存在 Q1 Q2 同时导通以短路电源的问题。为了防止事故发生，在输出端串联电阻器是一种安全的做法。

The time required for MOS to turn on from off to on is longer than the time from on to off. Reducing R1 can shorten the time from off to on. But it is not unlimited because the current pulling capacity of the driving source is limited.

When the control voltage changes from low to high, there is a 3V step at the beginning of the gate voltage. Analysis shows that it is caused by the 3.3 bias voltage feeding through the BC junction after Q3 is turned off.

In the switching state, the MOS tube needs to be closed and opened as quickly as possible, and this circuit can effectively control it.