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Old 10th June 2008, 03:50 PM   #21
luka is offline luka  Slovenia
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Hi

I had also no problems of anykind, didn't even clean anything, yet if worked ok
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Old 10th June 2008, 06:08 PM   #22
BWRX is offline BWRX  United States
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Quote:
Originally posted by theAnonymous1
The only thing I did differently with the TPA3106D1 board is put one inductor on each side of the board and I used 1uF WIMA MKS capacitors for the output filter instead of 1uF X7R ceramics. Could either of those things cause this problem, or could it just be a layout issue?
Try eliminating the possibilities one by one. Swap out the film caps for the ceramics and see what happens. If that doesn't change anything then try connecting one of the inductors to the board with short wires (~0.5 inch) and move the inductor around.

Very nice prototypes by the way
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Old 12th June 2008, 02:17 PM   #23
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Quote:
Originally posted by BWRX


Try eliminating the possibilities one by one. Swap out the film caps for the ceramics and see what happens. If that doesn't change anything then try connecting one of the inductors to the board with short wires (~0.5 inch) and move the inductor around.

Very nice prototypes by the way
Thanks Brian. I tried both changing the caps to ceramics and moving the inductors around with no change in temp.

The inductors heat up to around >100F with a room temp of 76F. Is that considered "hot"? Should I even worry about it?

A scope would make a really nice fathers day gift. Would it count as a gift if I buy it for myself?

EDIT: I forgot to mention the idle current draw is 50mA. The datasheet says it should be 14-17mA.
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Old 12th June 2008, 03:22 PM   #24
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Without the inductors connected the idle current draw is 16mA.

EDIT: When the ground point between the two 1uF caps is removed the idle current is normal. As soon as it is connected it goes back up to 50mA.

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Old 12th June 2008, 04:25 PM   #25
luka is offline luka  Slovenia
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LOOL? that shouldn't happen, bad PCB? you would really need scope right about now
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Old 12th June 2008, 05:19 PM   #26
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Oops.

Well, I found one major issue that fixed some of the problem. I had the MASTER/SLV pin driven LOW this whole time, meaning it was in slave mode, accepting a clock frequency on the SYNC pin.

I soldered a jumper wire from the MASTER/SLV pin to VREG and now the current draw is only 32mA instead of 50mA. The inductor temp is down to <90F.

I'm thinking the other problem is my layout. I didn't bother keeping the AGND and PGND seperate. I think I was so tired when I made it that it didn't even cross my mind that I should have.
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Old 12th June 2008, 05:56 PM   #27
luka is offline luka  Slovenia
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Hi

You could probably do better, but 20F is nothing, it is ok
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Old 13th June 2008, 05:07 PM   #28
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I finished my new layout. Doing the layout the way I do is very time consuming as everything is laid out manually; no nets at all. It's a royal PITA, but I can maximize the layout for how I hand make my PCBs.

I kept the AGND and PGND separate this time. They connect at one point; the thermal pad. Hopefully the 3 hours I spent on this was worth it.

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Old 14th June 2008, 07:55 PM   #29
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Finished the new board. This one has an idle current draw of 32mA like the other one after I fixed the oscillation problem. I feel better about the layout on this one at least.

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Old 14th June 2008, 11:03 PM   #30
luka is offline luka  Slovenia
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Hi

Sick board, you are getting very good at this Nice job
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