How to replace the damaged IC

Is there any other possibility other than the DAC IC being damaged for the VDD/VAA and GND line to be shorted?

Is there any way I could receive help from TI for this. I am based in New Delhi, if I can visit any TI facility in India which has people with such soldering experience, I would be willing to do so. I am a student and am not experienced with such fine soldering and fear that replacing the IC myself might result in damage to the board or other components. I have the EVM purchase details with me, if required. I know this is an unusual request but any help would be very much appreciated.

Thanks and regards,

Sufyan Khan

Okay thanks for the help.

Regards,

Sufyan Khan

Hello Uttam,

I was able to get the DAC IC soldered on the EVM but I am facing some issues. The hardware issue that I was facing(Short between VDD/VAA and GND line) was rectified after soldering the new IC. But now, I am not able to get output from the board.

The SPI communication is working fine as I checked reading the Device ID and other registers that I programmed, and the values matched as given in the datasheet(Device ID) or as what I programmed(Configuration registers). But even when I am communicating with the DAC, there is no voltage at the ouput.

Another thing I noticed is that the VIO line stays at voltage of 4.2V even when I am applying 3.3V.

I am not able to identify the problem. If you could help me it would be very helpful.

Thanks and regards,

Sufyan Khan

Hi Sufyan,

Could you please send the following details:

1. Jumper settings on the board

2. Power supplies as measured at different test points

3. Sequence of register settings

Regards,

Uttam

Please find my responses below,

1. Jumper settings on board:

J2 = open

J3 = open

J9 = closed

J10 = 1-2(selecting U2A3V3 from J7)

J11 = 1-2(selecting VREF from REF5025)

J12 = 1-2(selecting GND)

2. Power supplies at test points:

TP1 = 0.00V

TP2 = 0.00V

TP3 = 5.045V

TP4 = 5.044V

TP5 = 4.201V

TP9 = 0.011V

TP11 = 9.94V

TP12 = 2.487

TP13 = 0.00V

3. Sequence of registers

Register                       Value

SPICONFIG                 0A84

GENCONFIG               7F00

BRDCONFIG               FFFF

SYNCONFIG               0000

TOGGCONFIG0          0000

TOGGCONFIG1          0000

DACPWDN                  0000

DACRANGE(1-4)       0000

TRIGGER                     0000

BRDCAST                    0000

OFFSET(0-3)               0000

//INITIALIZATION COMPLETE

//WRITING VALUE  INTO DAC REGISTER

DAC7                            FFFF

Even after writing into the DAC7 Register, the output does not appear on the OUT7 pin.

Let me know if you need any more information.

Hi Sufyan,

Apologies for replying so late due to the holidays. Your VIO looks problematic. It should have been 3.3V but there might be another 5V source driving it. Please check that. 

I am assuming that you are able to read/write to the DAC properly. If that's not true, please upload a scope shot of the SPI pattern to debug.

As you resoldered the unit, you can check whether there are any shorts or dry-solder, etc. If yes, it might be a good idea to touch-up the soldering and check again.

Regards,

Uttam

Hi Sufyan,

Do you have an update on this?

Regards,

Uttam

Yes, I agree that the problem in with the VIO line. But I have not been able to find the reason for it not being 3.3V.

Yes, I am able to write and read from the DAC. I have checked the Device ID and also read back registers after writing values into them. SPI seems to be working fine.

This was my first thought as well, but I have cleaned the surface with solder flux and also checked for any dry solder or abnormality but didn't find anything. This is also due to the fact that most of the lead is beneath the IC which makes it difficult to check whether all the pins have been soldered properly.

I am stuck with this problem and have not been able to work on the DAC so far.