TAS5704: Does 350uV Noise Floor Make Sense with the TAS5704?

Wayne Chen (ex FAE)

Part Number: TAS5704

Hi Sirs,

With 24V PVCC, 6.8ohm load, does 350uV noise floor make sense with the TAS5704? My customer's found 240uV noise floor ith most of their TAS5704 devices, however, there is one corner case with 350uV noise floor. We can duplicate high noise floor problem with this chip on another system board.

Would you pls advise if 350uV noise floor make sense with the TAS5704 device? How to identify this noise floor problem if we can duplicate it on the EVM (we are planning to mount this NG chip to the EVM)? I got ~200uV noise floor on the EVM with a good TAS5704 device as a reference.

TAS5704 EVM:

Thank you and Best regards,

Wayen Chen
04/06 /207

over 7 years ago

0 Wayne Chen (ex FAE) over 7 years ago

Guru 15950 points

Hi Sirs,

Addition to my previous Email. I found 350uV noise floor is too high to the TAS5704. According to my measurement on the EVM with 24V PVCC and 6ohm load, the full scale input is -2dBFS. The Vout = 13.69Vrms with 0.1% THD+N. SNR = 101dBFS-A (112202V/V) in this case.

With this condition, the reasonable noise floor should be 13.69Vrms/1122202=122uV. Thus the TAS5704 device with 350uV could be problematic.

Would you pls advise if the FA process can identify any defect of this device?

Thank you and Best regards,

Wayne Chen
04/07/2017

0 Andy Liu (BMS) over 7 years ago in reply to Wayne Chen (ex FAE)

TI__Guru 52115 points

Hi Wayne,

We are not able to find any TAS5704EVM in our lab. However, we did find a socketed board for TAS5704. Allow us to check a few TAS5704 devices to confirm your results and then we can make a decision about whether to run a FA job.

Andy

0 Wayne Chen (ex FAE) over 7 years ago in reply to Andy Liu (BMS)

Guru 15950 points

Hello Andy, Thank you for your advise. Would you pls assist us to check this high noise floor device on the socket board (we can send this device to you early next week)? Thanks a lot...Wayne Chen

0 Roy Hsu over 7 years ago in reply to Wayne Chen (ex FAE)

TI__Genius 9260 points

Hi Wayne,

Unfortunately, we still couldn't find a proper socket to test with here. However, your calculation matched pretty well with the characterization data we have so we think that the device under test could be a defected device.

We suggest that you run the FA to see if there's a major difference between it and the normal device.

Thank you!

Best regards,

Roy Hsu

0 Wayne Chen (ex FAE) over 7 years ago in reply to Roy Hsu

Guru 15950 points

Hello Roy,

Thanks a lot. Would you pls send the shipping address and contact window to me by Email? We are going to send the TAS5704 NG chip and good chips to Dalla for FA.

Wayne Chen
04/19/2017

0 Jeff Kohnle over 7 years ago in reply to Wayne Chen (ex FAE)

TI__Expert 6985 points

Wayne, Did you get the address?

0 Wayne Chen (ex FAE) over 7 years ago in reply to Jeff Kohnle

Guru 15950 points

Hello Jeff, Thank you for your concern. Not yet. CQE team is doing standard FA process with this NG device...Wayne Chen

0 Jeff Kohnle over 7 years ago in reply to Wayne Chen (ex FAE)

TI__Expert 6985 points

OK, thank you! For any further feedback we'll work the normal QTS process via email. Thanks, Jeff

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TAS5704: Does 350uV Noise Floor Make Sense with the TAS5704?