irs2092 resetting with low frequencies.

nigelwright7557 · 5th February 2011, 10:36 PM

I have built a few irs2092 based class d amplifiers.

I thought it was working fine.
It does on low volumes but on high volumes and low frequencies it keeps resetting. If I apply 1khz then it clips well and doesnt reset.
If I apply 50Hz it gets to about 50% of B+ and keeps on resetting.

I have tried extra decoupling.
Tried increasing most of the capacitor values around the chip used for decoupling with no success.

I get an improvement if I add another pair of MOSFETs but the resetting still occurs but at a higher output voltage. This suggested overcurrent protection kicking in but raising the threshold makes no difference to the resetting problem.

luka · 6th February 2011, 06:45 AM

how are voltages around ic?
sounds like overcurrent or suppy pumping

savu · 6th February 2011, 07:31 AM

More like supply pumping to me...

luka · 6th February 2011, 08:25 AM

but, am not sure of that since there is no feature for this ic, but could be current related

nigelwright7557 · 6th February 2011, 02:13 PM

Quote:

Originally Posted by luka

how are voltages around ic?
sounds like overcurrent or suppy pumping

The voltages around the 2092 look fine.
Under resetting the vaa, vcc and vss are fine.
I have added extra capacitance to these lines and it still resets.

nigelwright7557 · 6th February 2011, 02:14 PM

Quote:

Originally Posted by savu

More like supply pumping to me...

The supply voltages dont go up during resetting.

luka · 6th February 2011, 02:34 PM

look at pins related with current sense/set. if this is the same amp as in other thread you have, could be that peak current is higher then set...so look at those pins

nigelwright7557 · 6th February 2011, 02:53 PM

Quote:

Originally Posted by luka

look at pins related with current sense/set. if this is the same amp as in other thread you have, could be that peak current is higher then set...so look at those pins

I tried making the overcurrent sense less sensitive but it made no difference.

I can only guess the inductor is saturating and taking masses of current.
I have ordered a 28amp inductor and will try that when it comes.

luka · 03:30 PM

but it doesn't have to go through inductor, shorts through fets are more likely. in any case, look if switching stops, if overcurrent is triggerd

28a inductor would be enough for pretty high powers

nigelwright7557 · 6th February 2011, 03:51 PM

Quote:

Originally Posted by savu

More like supply pumping to me...

If music is playing loud I get supply pumping.
The B+ goes from the normal 45 upto 70 volts.

I put a resistor across B+ to gnd to get rid of it but the resetting problem still persists.

5th February 2011, 10:36 PM	#1
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	irs2092 resetting with low frequencies. I have built a few irs2092 based class d amplifiers. I thought it was working fine. It does on low volumes but on high volumes and low frequencies it keeps resetting. If I apply 1khz then it clips well and doesnt reset. If I apply 50Hz it gets to about 50% of B+ and keeps on resetting. I have tried extra decoupling. Tried increasing most of the capacitor values around the chip used for decoupling with no success. I get an improvement if I add another pair of MOSFETs but the resetting still occurs but at a higher output voltage. This suggested overcurrent protection kicking in but raising the threshold makes no difference to the resetting problem. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

6th February 2011, 06:45 AM	#2
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	how are voltages around ic? sounds like overcurrent or suppy pumping __________________ home page @ http://www.classdaudio.co.cc @ 24/7 all year long I FEEL SLOVENIA

6th February 2011, 07:31 AM	#3
savu diyAudio Member Join Date: Feb 2007 Location: Cluj - Napoca	More like supply pumping to me... __________________ 1'st rule of chess: The only way to get smarter is by playing a smarter opponent.

6th February 2011, 08:25 AM	#4
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	but, am not sure of that since there is no feature for this ic, but could be current related __________________ home page @ http://www.classdaudio.co.cc @ 24/7 all year long I FEEL SLOVENIA

6th February 2011, 02:34 PM	#7
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	look at pins related with current sense/set. if this is the same amp as in other thread you have, could be that peak current is higher then set...so look at those pins __________________ home page @ http://www.classdaudio.co.cc @ 24/7 all year long I FEEL SLOVENIA


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6th February 2011, 03:28 PM	#9
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	but it doesn't have to go through inductor, shorts through fets are more likely. in any case, look if switching stops, if overcurrent is triggerd 28a inductor would be enough for pretty high powers __________________ home page @ http://www.classdaudio.co.cc @ 24/7 all year long I FEEL SLOVENIA Last edited by luka; 6th February 2011 at 03:30 PM.

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