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ADS122C04: ADC Circuit Review & Configuration Register Setting

CHO SR
Expert 2935 points
Part Number: ADS122C04
Other Parts Discussed in Thread: ADS1219

Hi

My client wants to implement DC Meter using ADS122C04.

There is a problem with ADS122C04 operation.

(-) ADC RAW data is read correctly at low current. (1A ~10A)

However, at the high current, ADC RAW data are outputted with a non-regular value. (11A ~70A)

The customer is asking for a solution.

1. Please review the circuit diagram 

2. review the Configuration Register

<Bipolar analog power supply>

Voltage measurement range: 450V to 550V

Current Measurement Range : (+)0.5A to 120A / (-)0.5A to 120A

Configuration Register

Register Set.xlsx

  • 0
    TI__Guru** 112895 points

    Hi Cho,

    There are a couple of things to be clarified.  First you have labeled the post as ADS122C04, but the schematic shows ADS1219.  The register settings are slightly different between devices, so I need to make sure which device is actually being used.

    If the ADS122C04 is the device being used, then the PGA needs to be disabled.  The register settings you have sent show the PGA as enabled which violates the input range of the PGA for single-ended measurements based on the schematic.  You state that bipolar analog supplies are used, which would then allow the PGA to be enabled, but again the schematic does not show bipolar supplies.  If the ADS1219 is being used, then unipolar supply must be used as the ADS1219 does not allow for bipolar supply operation.

    As the current measurement must be using a low-Ohm shunt, the location of the shunt relative to the input of the ADC becomes critical.  Can you give more details on the current measurement?

    For the voltage measurement the filter values should be consistent.  In other words the value of R27 and R32 should be the same.

    Best regards,

    Bob B