This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADC34J43EVM: ADC Data Code always keep ~8200

Part Number: ADC34J43EVM
Other Parts Discussed in Thread: TSW14J50EVM,

Dear TI E2E,

I have two problem which using ADC34J43EVM and capturing by TSW14J50EVM.

I follow the ADC3xxx, ADC3xJxx EVM User’s Guide to setting EVM broad, ADC3000 GUI, and HSDC Pro.

1.

I connect CIN_P to GND.

But the ADC code which record by HSDC is about 8200.

Is this ADC measure voltage = 2 * 8200 / (2^14) ~= 1.00 V?

But the CIN_P seems 0 V.

I not sure which setting is wrong.

2. 

I CIN_P input 1V with series resistance of 1k ohm.

In the spec, the input impedance is 6.5k ohm.

But when I measure the voltage of resistance seems very low.

Thanks for your help. I look forward any suggestion from you.

  • User,

    The board is AC coupled by default. Are you bypassing the transformers and AC caps when you are doing this test?

    Regards,

    Jim

  • Dear Jim,

    Sorry. I don't bypass those.

    If I want to detect DC can I change the broad(remove the R1 & R14; AIN_P connect to DC; AIN_N connect to GND) as follow figure?

    Thanks for your help.

    Andy Wei

  • Andy,

    I would connect two separate DC voltages instead of one and GND. Then set both voltages so that they are always symmetrical and do not exceed +/1V for each. The ADC should send out midscale data with both set to 0.95V (VCM). If you increase the AIN_P input and decrease the AIN_M input by the same amount, the ADC will count above midscale. It will count down below midscale if you do the opposite. 

    Regards,

    Jim