ADC12DJ5200RFEVM: Is sysref not required for on-board clock operation?

user5788058

Hi,

I have a question regarding SYSREF when running the ADC12DJ5200RFEVM with the onboard clock.

I replaced the capacitor and resistor according to the user guide and set the clock source to on-board in EVMGUI, Fs = 5200 Msps, JMODE 1.

I was able to obtain the waveform of the sine wave input with this setting. However, in this configuration, the LMX's OUTB is powered down, and the SYSREF appears not to be input to the ADC.

To be honest, I'm not familiar with JESD, but I thought SYSREF was a must in subclass 1. Why does this ADC work?

over 5 years ago

0 Rob Reeder over 5 years ago

TI__Mastermind 38690 points

Hi,

The ADC will work without the use of Sysref, until the application calls for synchronization of multiple converters (multi-Rx or multi-Tx, or Rx & Tx).

In subclass 1 the SYNC is required, not the Sysref when using only one converter, as in the case of the 5200 EVM.

Here is one useful link that describes and outlines JESD.

http://www.ti.com/lit/ml/slap161/slap161.pdf

Hope this helps.

Regards,

Rob

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ADC12DJ5200RFEVM: Is sysref not required for on-board clock operation?