Drivers and FETs destroyed, Help Please - diyAudio
Go Back   Home > Forums > Amplifiers > Class D
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 9th June 2007, 05:50 PM   #1
smitten is offline smitten  United Kingdom
diyAudio Member
Join Date: Sep 2006
Default Drivers and FETs destroyed, Help Please


I have designed a class D outputstage and it has worked perfectly untill today when I made a stupid mistake and destroyed it.

I am using irs20124s MOSFET drivers and IRLIB4343 MOSFETs in a full bridge configuration.

I had no load on the outout and was measuring the output signal by connection the probe to the upper mosfet source pins. I then moved the probe so I shorted the source and drain on the upper mosfet. Big sparks and the usual smell.

Since I shorted the upper fet i thought only the lower fet was destroyed and the problem isolated to on of the two complementary output stages(full-bridge). I then noticed that both drivers had a short between input and positive rail and also the buffer before the drivers was damaged. I use 10Ohm gate resistors.

If a fet is destroyed does the gate become connected to the drain? This could have damaged the driver connected to the mosfets i shorted. But how did the second driver get destroyed? It was not even connected to the other half side through a load. I just cant see how both drivers were destroyed.

Any ideas on this? Do you think I should just change both drivers and 4 FETs and try again or is there a resonable chance some can be reused?
  Reply With Quote
Old 9th June 2007, 06:33 PM   #2
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
Join Date: Jan 2005
Location: Pennsylvania
Default Re: Drivers and FETs destroyed, Help Please

Originally posted by smitten
If a fet is destroyed does the gate become connected to the drain?
Often, you will see a short between all three pins of a damaged MOSFET.

Just because there was no load connected doesn't mean there was no way for current to flow from one half bridge to the other. Both high side MOSFETs are connected to the same supply rail and both low side MOSFETs are connected to ground. The driver chips are both connected to ground and probably to the same Vcc supply as well. There are lots of strange ways current from one half bridge can end up flowing through the other.
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Are my two TDA1562 destroyed?? newbadboy Chip Amps 2 10th June 2009 12:13 PM
destroyed 10" Animalnisse Swap Meet 0 8th January 2007 02:19 AM
SG3525 destroyed MOSFETs SMPS3525 Power Supplies 16 21st September 2006 12:38 AM
Bad AC recepticle destroyed my stuff! Destroyer OS Everything Else 87 19th April 2006 10:37 PM
Is SAA7378GP destroyed? Gasho Digital Source 5 8th August 2005 04:10 PM

New To Site? Need Help?

All times are GMT. The time now is 03:06 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2