ADC12DJ3200: differential inputs P and N swapping

LALIT VERMA

Part Number: ADC12DJ3200

Hi TI,

We are using ADC12DJ3200 in our design.

I have checked the eval board layout, and in layout Balun Negative side output is connected to ADC’s Positive side differential input.

Does this ADC have some internal circuitry which swaps the inputs internally that is if ADC’s P and N inputs are connected to balun’s N and P outputs respectively ,accidentally or intentionally , can we swap the P and N input internally through programming?

Thanks,

Lalit

over 4 years ago

0 jim s over 4 years ago

TI__Guru* 91947 points

Lalit,

We are looking into this.

Regards,

Jim

0 LALIT VERMA over 4 years ago in reply to jim s

Expert 1635 points

Hi Jim,

Please update on this.

Thanks,

Lalit

0 Neeraj Gill over 4 years ago in reply to LALIT VERMA

TI__Mastermind 20541 points

Hi Lalit,

The P and N swap was done to make the layout easier. But there is no way to un-swap it in the ADC with software.

Regards,
Neeraj

0 LALIT VERMA over 4 years ago in reply to Neeraj Gill

Expert 1635 points

Hi Neeraj,

As this ADC has two channels, and in eval layout for channel 1 balun output's P and N is connected to ADC inputs P and N but channel 2 balun output's P and N is connected to ADC inputs N and P.

Does this generate the inverted digital data like output data which should be 1 is 0 now and vice-versa.

Does we need to invert the data in FPGA?

Thanks,

Lalit

0 LALIT VERMA over 4 years ago in reply to LALIT VERMA

Expert 1635 points

Hi TI,

Please update on this.

If we invert the P and N connection of ADC input then do we need to invert data in FPGA.

Thanks,

Lalit

0 LALIT VERMA over 4 years ago in reply to LALIT VERMA

Expert 1635 points

Hi TI,

Can you please update on this?

Thanks,

Lalit

0 LALIT VERMA over 4 years ago in reply to LALIT VERMA

Expert 1635 points

Hi Guys,

Can you please update whether we need to do something with the digital data in FPGA ,we obtained from ADC by swapping the P and N inputs of ADC with N and P outputs of Balun?

An early response will be highly appreciated.

Thanks,

Lalit

0 Neeraj Gill over 4 years ago in reply to LALIT VERMA

TI__Mastermind 20541 points

Hi Lalit,

Since P and N inputs are swapped on CHA vs CHB. The output data from CHA will be 180 degree out of phase from output of CHB if you care about the phase relation of CHA vs CHB. Please change the phase of CHB by 180 degree to allign the output data. If you don't care about the phase relationship between two channels then you don't have to do anything.

Regards,

Neeraj

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ADC12DJ3200: differential inputs P and N swapping