TSW1405EVM: Glitches when using the HSDC Pro and the TSW1405 with the asd5474evm

Ayoub,

The IF input is saturated. You must lower the amplitude so that the fundamental power is less than -1.0dBFs. You currently have this power at 0.6dBFs.

Regards,

Jim  

Hi Jim, 

Thank you for the answer,

I've just tried to, it didn't resolve the problem, almost same results ( bad SNR/ENOB )... and still have the glitches:

For a 50Mhz Input :

For 700 Khz Input:

For both the clock frequency is 200 MHz, 

Thanks,

Best regards,

Ayoub,

Ayoub,

I think you may have an issue with your input signal. With a 50MHz input tone and a 200MHz sample rate, you will only have 4 samples per cycle. The signal should look like the one shown in the attachment. This was using an ADS5463EVM with a TSW1405EVM sampling at 200MHz with a 50MHz input tone. I would suggest probing the analog input at the ADC pins to verify you have a valid input. 

Regards,

Jim  

ADS5463EVM.pptx

Hi Jim,

Thanks again, 

I do only have 4 samples per cycle as well for a 50 MHz input signal when sampling at 200 MHz, but I get a bad SNR and ENOB, I've just haven't attached it because we can not see the glitches when we have 4 samples per cycle ( and my problem is as I think with the glitches), I wanted to show the glitches when I have as many samples to reconstruct the sine wave.

Attached are the snapshots for the 50 MHz input signal codes and FFT for two different captures, and the analog input probing at the R19 and R20 resistors.

Thanks in advance,

Best regards,

Ayoub

Ayoub,

Try slowing down the sample rate to something like 100MHz and use a 7MHz input tone. Do you see the same issues? Check the bits output as shown in slide four of the attachment. I am trying to figure out if the issue is with the ADS5474EVM or the TSW1405EVM. The TSW1405EVM is powered up using the 5V on the USB input cable. Can you try using a different USB port or PC to see if this helps? 

To power the TSW1405EVM with an external supply, you would remove R42 and connect 5VDC to TP2.

Make sure the current limits are not set to low on the supplies connected to the ADS5474EVM. Are you using the transformer stage or the amplifier stage of the EVM? 

Regards,

Jim 

3441.ADS5463EVM.pptx

Hi Jim,

Thanks for your help,

I slowed down the sampling rate at 100 MHz, and I used both 7MHz and 700KhHz input tones, still have the same issues, snapshots are in the attachment.

I've already removed the R42 and I am using an external supply to power the TSW1405, and I'm connecting 5 VDC to TP2 and TP1 to ground. I had the same problem before removing the R42 and when using the 5V on the USB cable to power up the TSW1405.

I'm setting the current limit to 1 A on the supplies connected to the ADS5474EVM which is so much higher than it needs.

I'm using the transformer stage of the EVM.

Best regards,

Ayoub,

ADS5474-700Khz_and_7MHz_at_100MHZ.pptx

Ayoub,

It appears you may have a bad board. Problem is, I cannot tell which one. If I was to guess, I would pick the TSW1405EVM. If you happen to have access to a TSW1400EVM, you could use this platform to test the ADS5474EVM.

I would suggest requesting an exchange for the TSW1405EVM.

If you bought this from a distributor, you will have to work with them to get a replacement. If you bought it from the TI Store, the following link has the details and a link to the form to start the return process.  Once you are on the returns and refunds page of the TI Store look for the hyperlink which says: TI store customer support form. 

Regards,

Jim

www.ti.com/.../ti-store-order.html

Hello Jim, 

Thanks for your help, 

I do not have the TSW1400EVM..

Don't you think it might be a firmware problem of the TSW1405 with the ads5474 and some ADCs ?  Here is a screenshot of someone's issue using the TSW1405, he's using a different ADC and he wasn't asking about the glitches, but I've seen the glitches on his snapshot and wondered.. Just wanted to make sure it's not a software problem..

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/807107/tsw1405evm-afe5809?tisearch=e2e-sitesearch&keymatch=TSW1405EVM#

Thanks again, 

Best regards,

Ayoub,

Ayoub,

I had no trouble with the software when testing with an ADS5463EVM at 500MHz sample rate.

Regards,

Jim

Hello Jim,

Okay, great ! So it's a board defect ! 

Thanks a lot ! 

Best regards,

Ayoub,

This is what I am suspecting.