TSW1400EVM: Single bit errors reading AFE5808A

David Christian

Part Number: TSW1400EVM
Other Parts Discussed in Thread: AFE5808A, AFE5808AEVM, AFE5808

I am using an AFE5808A Evaluation board (together with a TSW1400 data capture board). I am trying to measure figures of merit including signal to noise and distortion ratio using an external clock, but I think my measurements are currently limited by bit errors reading out the AFE5808A. The clock I am using is a sine wave at 62.5MHz and 2.825Vpp into 50Ohms. If I put the ADC into the ramp test mode, I see ramps on all 8 channels, but all channels have occasional single bit errors... usually in the 2^5 bit (error of 32). I see fewer errors if I set the external clock frequency to 31.25MHz, but the errors do not completely disappear. Do you have any idea what I'm doing wrong or how I can eliminate these bit errors?

over 4 years ago

0 Chen Kung over 4 years ago

TI__Genius 12025 points

Hi, Thank you for using TSW1400EVM.

We will look at your question very soon.

Thank you!

0 Chen Kung over 4 years ago in reply to Chen Kung

TI__Genius 12025 points

Hi,

When you are using TSW1400EVM to capture AFE5808AEVM,

please make sure the P10 connector (on AFE5808AEVM) must be connected very tightly to TSW1400EVM.

Please also double check on AFE5808_08A User's Guide's Figure 1 on page 3,

since you are using an external clock source, please check all the Jumpers' connections with Figure 1 page 3.

Please follow all the jumper connections shown in red color

to make sure they are correct or not.

especially please connect the JP9's two jumpers at "EXT" (but not "OSC") location for your case.

And also make sure to connect your external clock to J15 (but not JP15).

Thank you!

0 Chen Kung over 4 years ago in reply to Chen Kung

TI__Genius 12025 points

Please make sure to connect your external clock to J15 (but not J14).

please still keep JP15 jumper connection shown in Figure 1 on page 3.

Thank you!

0 David Christian over 4 years ago in reply to Chen Kung

Prodigy 60 points

I verified all the connections and tried again yesterday. I still see readout errors when I use a 62.5 MHz clock. I tried a 40 MHz external clock (also 2.825V sine wave (50ohm)) and then everything worked as expected---no readout errors with AFE set to output a ramp.

0 Chen Kung over 4 years ago in reply to David Christian

TI__Genius 12025 points

Hi,

Let's assume when you are using the 62.5MHz external clock source.

Could you please let me know what kind of the external clock you are using?

Thank you very much!

Best regards,

Chen

0 David Christian over 4 years ago in reply to Chen Kung

Prodigy 60 points

The external clock comes from a BK Precision 4065 Arbitrary Waveform Generator on a 50 Ohm coax to the evaluation board. The clock is a sine wave with amplitude = 2.825V into 50 Ohm (the user guide says 13 dBm). When I set the frequency to 40MHz and set the TSW1400EVM software to 40M ADC clock, I see no errors. When I set the frequency to 62.5 MHz and set the TSW1400EVM software to 62.5M, I see occasional errors on all channels.

0 Chen Kung over 4 years ago in reply to Chen Kung

TI__Genius 12025 points

Hi,

Also when you are connecting your external clock to the AFE5808AEVM's J15,

since there is on-board 50ohm termination already built,

(you can see on User's Guide Figure 26 page 38)

therefore please don't connect another 50ohm to the J15 SMA.

Thank you!

0 David Christian over 4 years ago in reply to Chen Kung

Prodigy 60 points

I'm not using a 50 ohm terminator... I just meant that I set the waveform generator to expect a 50Ohm load.

0 Chen Kung over 4 years ago in reply to David Christian

TI__Genius 12025 points

Hi,

Usually when running clock source,

we need very low noise external clock source as the input clock.

since this topic is out of the device issue,

is it possible if you can provide your email address?

If for another new question, please assign and can discuss in next thread.

Thank you!

+1 David Christian over 4 years ago in reply to Chen Kung

Prodigy 60 points

My email address is dcc@fnal.gov.

0 Chen Kung over 4 years ago in reply to David Christian

TI__Genius 12025 points

Thank you!

Data converters

Data converters forum

TSW1400EVM: Single bit errors reading AFE5808A