MOS tube bidirectional current flow problem

肖柳子

MOS tube bidirectional current flow problem [Copy link]

MOS tubes can flow current in both directions. In the reverse direction, does the current flow through the channel or...?

maychang

"In the reverse direction, does the current flow through the channel or what?" If the MOS tube is in the on state, the current flows through the channel. If the MOS tube is in the off state, the current flows through the internal parasitic diode. However, the author's Chinese level is worrying. After "or", there must be another option besides "channel". Even if you don't know the name of the other option, you should say "Does it flow through the channel or where?"

qwqwqw2088

The problem described by the OP is indeed a bit... In the reverse direction, the MOS tube is also turned on. After the MOS tube is turned on with a driver, the current flows through the channel. Bidirectional flow is its characteristic. If the gate is not driven, it is impossible to turn on in the reverse direction.

肖柳子

maychang posted on 2018-7-10 15:26 "In the reverse direction, does the current flow through the channel or what?" If the MOS tube is in the on state, the current flows through the channel. If the MOS tube is in the off state, the current...

Haha, I know I'm wrong

肖柳子

qwqwqw2088 Posted on 2018-7-10 15:37 The problem described by the OP is indeed a bit... The MOS tube is also turned on in the reverse direction. After the MOS tube is turned on, the current flows through the channel. The bidirectional flow is...

Oh haha, I see. As long as the control voltage is in the on-state, the current flows through the channel, and vice versa.

肖柳子

qwqwqw2088 Published on 2018-7-10 15:37 The problem described by the OP is indeed a bit... The MOS tube is also turned on in the reverse direction. After the MOS tube is turned on by a driver, the current flows through the channel. The bidirectional flow is...

I have tried it. If the gate control voltage does not exist (PMOS tube Vgs=0, because the turn-on threshold is -10v), but current flows in the reverse direction, is it because of the internal diode?

maychang

Xiao Liuzi published on 2018-7-10 16:43 I have tried it. If the gate control voltage does not exist (PMOS tube Vgs=0, because the conduction threshold is -10v), but there is current flowing in the reverse direction, is it because...

You measure the reverse current and the MOS tube voltage drop. When the MOS tube channel is turned on, the voltage drop is equal to the MOS tube Ron (on resistance, usually a very small value, which can be found in the manual) multiplied by the current, which is generally less than 0.7V, and often much smaller than 0.7V. When the internal diode of the MOS tube is turned on, the voltage drop is about a PN junction voltage drop, about 0.7V.