Motor control circuit is blowing mosfet driver (tc4429)

Thread Starter

woerr

Joined Apr 5, 2015
40
Below is my circuit, when the driver is disconnected from he mosfet the driver works perfectly and does not get warm, when the mosfet and motor are connected all tc4429's get warm but keep working for some time but then eventually burn and stop working, they get warm regardless if the mosfet and motor are disconnected or connected after they do it once. last strange thing I have noticed is when I have multiple of these drivers connected to different inputs and different mosfets and motors when one motor is connected to one of the drivers all the tc4429's blow, as if the power source spikes or dips. I have pretty cheap oscilloscope but I can not see any voltage spikes on the output of the mosfet driver while it is working. Please help! exp.png
 

Alec_t

Joined Sep 17, 2013
11,388
o_O Your board pic seems to show pins 1,4,5,8 of the driver IC all grounded, if "|||" denotes ground?
Are you using a star ground system? If not, heavy load current may be causing ground bounce which is upsetting the driver IC.
 

shortbus

Joined Sep 30, 2009
7,753
Why the capacitor (3900pF) on the gate drive output? Never seen that before, won't that increase the mosfet turn on time? Which wouldn't be good for either the driver or the mosfet. Since the gate is already in effect a "capacitor".
 

Picbuster

Joined Dec 2, 2013
1,007
I agree with shortbus the cap 3900 is creating an integrator disallowing the gate to open quickly resulting in a higher s-d impedance.
Please observe the gate voltage and shape.
What voltage is needed to get the fet in full conductance and is that voltage available? (I think 4.5V but not sure )
 

Thread Starter

woerr

Joined Apr 5, 2015
40
I agree with shortbus the cap 3900 is creating an integrator disallowing the gate to open quickly resulting in a higher s-d impedance.
Please observe the gate voltage and shape.
What voltage is needed to get the fet in full conductance and is that voltage available? (I think 4.5V but not sure )
It was the closest I could find to 2500pF as per the datasheet.

http://ww1.microchip.com/downloads/en/DeviceDoc/21419D.pdf

I have scoped it and the wave seems perfect.
 

bertus

Joined Apr 5, 2008
20,564
Hello,

The shown capacitor is a test capacitor for measuring the rise and fall time.
This is a replacement for the measurement in stead of the gate capacitor IN the mosfet.
In real life the capacitor must not be used.

Bertus
 

Thread Starter

woerr

Joined Apr 5, 2015
40
Thanks, I will remove it, it wont fix my burning ic problem though. Would it work to add two p channel mosfets to make a Single H-bridge setup.
 

bertus

Joined Apr 5, 2008
20,564
Hello,

What are the specs of the P595 device (R43) near the gate of the mosfet?
What will be the gate voltage?

Bertus
 

Thread Starter

woerr

Joined Apr 5, 2015
40
so the problem was spikes coming through the 12 volt supply from motor. it was spiking up to 16v that was blowing the driver chips. What would be the best way to solve this issue, at the moment I moved the 12 supply for the control circuit to the source which removed the problem.

What is a good way to smooth the supply?

H-bridge?
voltage regulator?
 
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