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MOSFET driver killed mysteriously and need help

hi to everyone. I mysteriously killed 5 MOSFET half bridge drivers and wish to see if anyone can help.

I'm making a N-MOSFET H bridge circuit that switch a sine wave output using unipolar PWM for an inverter project. The gate driver I choose was IR21834 and I began testing half of the bridge on breadboard according to the datasheet circuit. Connecting input lines manually to V+ or GND to produce the output, the lower MOSFET would first work, but it always happened that somehow after changing the circuit such as connecting driver input here and there or switching the value of boostrap capacitor, at a random time the chip would go crazy . The chip would feel hot touch, followed by increase in current drawn, all of which signifying an internal short circuit. It seems the hide side circuit is causing problem, since the low side output would usually still functioning afterwards.

I believe such short circuit behavior can only be caused by shorting high side output to ground or to V+, and I swear I didn't, nor did I connect bootstrap diode and capacitor wrongly (I redid the circuit several times and same error can't happen over and over again). I thought it might be chip design problem but as I tried chip from other manufacture, L6388 from ST, the same happened. Now I'm really threatened as I don't want to kill any more chips. Although I might find out the reason myself but that would probably take another 10 chips dedicated to destroy, and this is why I ask for help here.

While not expecting a direct reason to the problem, I am REALLY REALLY glad if someone who have killed MOSFET driver before (for whatever reasons) to share his/her story, and also tell me what to avoid when working with drivers, thousands thanks in advance!

Reply to
w2kwong
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What was the output connected to during this test? Do you get the same problem if you attach it to a resistive load such as a light bulb?

Reply to
larwe

The maximum voltage permissible on the IGBT's or MOSFETs is 60VDC. Are you under this?. See also the application notes.

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Reply to
Paul E. Bennett

Those flashy European sports cars are death traps. He should have been wearing his seat belt.

Reply to
John Speth

This picture shows what I did:

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(NOTE: bootstrap diode is built in)

Reply to
w2kwong

What you did with what?

-- "A man who is right every time is not likely to do very much." -- Francis Crick, co-discover of DNA "There is nothing more amazing than stupidity in action." -- Thomas Matthews

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Reply to
CBFalconer

Hi w2kw...

robust than any IR counterpart.

  1. There should alway be a resistor between driver and mosfet
  2. 1000uF bootstrap cap is an overkill, and electrolyts are hardly apropriate for this kind of application. We usually use 2u2 tantalum cap.
  3. there is no blocking caps near the half bridge and gate driver.

I recommend reading AN944, AN1299 from ST and DT98-2a, DT04-4 and DT97-3 from IR

Regards, Mitja

Reply to
korenje

As someone else said, a gate resistor is a good idea, particularly with non-ideal layout. I don't see the connection between ground and low-side MOSFET source.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

Hi Spehro, the little orange wire at bottom is low side connection to ground. I use the circuit to test whether the driver's output corresponds to input.

Hi Korenje, could you say a bit why you think ST is not as good as IR's driver?

THX

Reply to
w2kwong

Out pin undershoot (at high side FET turn-off) and bellowground voltage (when current is flowing through low side freewheeling diode). Putting 13V Zener diode in parallel with Cboot helped and also moving High side gate resistor between high side FET source and driver helped.

We deduced that at the high side turn-off the negative voltage transient on Vs/Out pin causes the voltage across bootstrap pin and Vs/ Out pin (note: not the voltage on bootstrap capacitor) goes well beyond +15V this blowing high side driver collapse which in turn causes low side driver collapse. If you don't have the option to limit DC link current both FET's also blow.

When we replaced L6387 with IR2101 (on the same power stage) none of the above mentioned steps were required to take to assure proper operation.

Regards, Mitja

Reply to
korenje

Yes, but how does that get to pin 4 (?) on the driver chip?

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

May I suggest a post to "sci.electronics.design" or "sci.electronics.components"

Reply to
TheDoc

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