Go Down

Topic: 12v vacuum and arduino (Read 921 times) previous topic - next topic

wvmarle

He did say gate-source.
True. I assumed it's a typo, which would come as no surprise here.

Quote
In the datasheet, such a diode - two back-to-back Zeners - is shown.
Interesting. Gate protection maybe? No word in the data sheet about this.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

MarkT

Definitely gate protection diodes - very useful to have that, first line of defence against gate-oxide failure and
careless handling.  Downside is gate leakage currents may be higher than standard MOSFET, affecting gate
driver bootstrapping capacitor choice.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

TimChPi

What board is that?
What board is this?  Where is/ was the link to a board?

The gate grounding resistor is to keep the FET switched off when the Arduino is reset and its pins are effectively inputs and may float.  Since this problem belongs to the Arduino rather than the FET, the resistor should be across the Arduino pin to ground.  If it is on the FET gate, after the series resistor, then it tends to form a voltage divider and reduce the voltage turning on the gate.  That may be a minor effect, but it makes sense to avoid even minor impediments to performance.
To protect against ESD (Electrostatic discharge).

How does a back to back Zenor protect against the ESD?

wvmarle

It conducts in either direction when the voltage is higher than the reverse voltage of one and the forward voltage of the other. So a pair of 25V zeners (no o in there) would conduct at about 26V - either direction - limiting VGS to about that level.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Go Up