MOSFET driver killed with no particular reason

Guest
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 direct reasons 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!
 
w2kwong@hotmail.com wrote:
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 direct reasons 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!
Click to expand...
Did you read the appnotes? Can you post a schematic?
(on ABSE or with a link to a website or ASCII here)

Ed
 
Hi,

There are several issues but usually the gate resistor is not large enough
plus you must have a diode around this resistor and a resistor in series
with the diode. ( the current mirror issue ) the Crss is being charged with
the turn on gate resistor. The resistor in series with the diode ( turn off
resistor ) should about 1/10th the value of the turn resistor. This is
because when you turn on the fet the other fet in series is seeing the same
dv/dt. so the turn off resistor should be low enough to keep from pulling
the gate up to the threshold voltage. When you have selected the turn on
resistor the driver chip will run cooler because it will have to deliver
less charge. It is totally impossible to drive fets in a half bridge or full
bridge( with any current ) with out series gate resistors.
Ray

<w2kwong@hotmail.com> wrote in message
news:1176911909.411398.111240@b58g2000hsg.googlegroups.com...
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 direct reasons 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!
Click to expand...
 
Hi again
I forgot something, The boot strap diode must be at least as fast as 200ns.
The boot strap cap should be 1 uf and the ground cap at the anode end of the
fast diode should be at least 10uf.
I hope this is helpful
Ray


<w2kwong@hotmail.com> wrote in message
news:1176911909.411398.111240@b58g2000hsg.googlegroups.com...
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 direct reasons 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!
Click to expand...
 
w2kwong@hotmail.com wrote:
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 direct reasons 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!

my guess your loaded with static..
Click to expand...
try putting on some anti-static straps on your wrists.


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
 
First thanks for replying.

Humidity last night was 60% and this excludes possibility of
electrostatic, plus I have played with CMOS gates 74HC, 40XX without
anti-static for ages without encountering a single chip killed for
this. Ray suggested that Rg is source of problem, but I was only
manually bring the input on and off, not yet with high frequency. The
gate is in order of nF and can't see how a single charge up could
cause current large enough to blow the driver. With IR21834 which have
more then 1A capability, the chip actually burned and drawed more then
1A from 12V supply, obviously an internal short circuit...

This picture shows what I did:
http://www.geocities.com/w2kwong/MOSFET.jpg
(NOTE: bootstrap diode is built in)
 
On 18 Apr 2007 20:18:35 -0700, w2kwong@hotmail.com wrote:

First thanks for replying.

Humidity last night was 60% and this excludes possibility of
electrostatic, plus I have played with CMOS gates 74HC, 40XX without
anti-static for ages without encountering a single chip killed for
this. Ray suggested that Rg is source of problem, but I was only
manually bring the input on and off, not yet with high frequency. The
gate is in order of nF and can't see how a single charge up could
cause current large enough to blow the driver. With IR21834 which have
more then 1A capability, the chip actually burned and drawed more then
1A from 12V supply, obviously an internal short circuit...

This picture shows what I did:
http://www.geocities.com/w2kwong/MOSFET.jpg
(NOTE: bootstrap diode is built in)
Click to expand...
Don't use plug-in boards for power control circuits.

RL
 
You have stray inductance all over the place with those plug in boards.
Also they are capacitive and radiate like a Son of a gun. This is fine for
low speed digital or simple analog opamp circuits but definately not for
high speed PWM. When you thrn the FETs on and off, you're getting spikes
all over.

You need a PCB with wide, short traces to minimize the inductance.

I have tried making switching power supplies on perf board using copper tape
and short wires and it never even came close to the performance of a proper
PCB layout. The perf projects were usually unsuable.




<w2kwong@hotmail.com> wrote in message
news:1176952715.782498.14510@o5g2000hsb.googlegroups.com...
First thanks for replying.

Humidity last night was 60% and this excludes possibility of
electrostatic, plus I have played with CMOS gates 74HC, 40XX without
anti-static for ages without encountering a single chip killed for
this. Ray suggested that Rg is source of problem, but I was only
manually bring the input on and off, not yet with high frequency. The
gate is in order of nF and can't see how a single charge up could
cause current large enough to blow the driver. With IR21834 which have
more then 1A capability, the chip actually burned and drawed more then
1A from 12V supply, obviously an internal short circuit...

This picture shows what I did:
http://www.geocities.com/w2kwong/MOSFET.jpg
(NOTE: bootstrap diode is built in)
Click to expand...
 
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