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ADS114S06: Current consumption of ADS114S06 Vs ADS124S08

JC
Prodigy 180 points
Part Number: ADS114S06
Other Parts Discussed in Thread: ADS124S08

Hello,

We have a battery powered system that we originally designed using the ADS124S08, we have recently switched to the reduced performance ADS114S06 and have noticed around 50 uA more current draw on average with the new ADC. From the data sheet the power consumption looks identical.

Can anyone point me in the right direction as to what could be causing this? This is the only change on the board. We compared 2 identical firmware versions and the ADS114S06 was drawing more current on average.

The register configuration is like below:

NPMUX: 0x12
PGA: 0x09
DATARATE: 0x3C
REF: 0x11
IDACMAG: 0x05
IDACMUX:0xF0

We have configured the ADC(s) in single shot mode, this is our procedure every 50ms:
  • send WAKEUP command
  • wait 7ms
  • send START command
  • wait 1ms
  • send RDATA command (3 bytes for ADS124s08, 2 bytes for the ADS114s06)
  • send POWERDOWN command

Any help is appreciated.

Thanks

  • 0
    TI__Guru** 113765 points

    Hi Jonathan,

    How have you determined that the current is being drawn by the ADC and not by some other source such as from a boost regulator inefficiency? Have you used the identical BOM in the build except for the ADS114S06?

    As to any differences between the ADS124S08 and the ADS114S06, other than register settings and resolution there really should not be any differences.  However, if you are using the ADS114S06B, it is possible there could be some differences as some of the specifications are not guaranteed. 

    If it is from the ADC, can you be more specific as to whether or not the current is coming from AVDD, DVDD or IOVDD supplies?  It would be helpful to know which supply the additional current is coming from to narrow down some potential areas.  One often overlooked aspect of powering up and down the internal reference is the charge/discharge of the internal reference cap.  Depending on the length of power-down time, more charge could be depleted by the charge and discharge of the cap as opposed to just leaving the internal reference on all of the time.

    Best regards,

    Bob B