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ADS1232: Bridge Sensor Applications

Yusuke Mukuno
Expert 7395 points

Part Number: ADS1232
Other Parts Discussed in Thread: ADS1231, ADS131M02, ADS1235, ADS122C04, ADS1220, ADS122U04, ADS124S06

Hi Expert,

My customer is considering ADC for Bridge Sensor input.

Usecase

Ch1 : PGA gain = 128, need 24bit, Input signal range = 0.1mV to 10mV,  continuous measurement

Ch2 : PGA gain = 1,  not need 24bit, Input signal range = 0V to 3V, measurement when their system  request from MCU, sometimes.

Question1. 

Is ADS1232 suitable for this use case?

Concern ; Different gain between Ch1 and Ch2. they need to control Gain0 pin and Gain1 pin at each channel measurement.

In other words, should they use 1ch device (ADS1231) for ch1 measurement? and should they use the integrated ADC in the MCU for ch2 measurement?

Question2

They are lookin for lower power consumption ADC for this usecase.

Do you have any recommended device?

I seems, ADS131M02 have independent PGAs for each channels. Can they use it for Bridge Sensor Applications?

Do you have any idea for other devices?

Thnaks

Muk

  • 0
    TI__Guru** 113765 points

    Hi Muk,

    This would seem like a simple answer, but it is not clear what the total requirements are for the application.  In particular, the power requirements and the level of precision for the bridge measurement.  Another factor is time required for each measurement.  For example, the ADS1232 (and ADS1231) operate at 10sps and 80sps output data rates.  These devices also have a sinc4 filter, so when the mux is changed the device will take 4 complete conversion before the digital filter settles with the proper output result.

    There are much fast devices, such as the ADS131M02 which does have simultaneous sampling converters and could be used in the application.  However, the faster the conversion and with multiple devices the power increases considerably.

    So there are a number of potential devices besides the ones already mentioned such as the ADS1235 and ADS124S06.  However if power is a big consideration, the ADS1220 is a great solution for power savings, with 2 differential inputs and speeds up to 2ksps in turbo mode.  The ADS1220 also has a PGA up to 128 and can make single-ended measurements.  Configuration between channels can take place in full-duplex communication where the 2nd channel is setup for configuration the same time data is read from the first channel.  The ADS1220 also has non-SPI variants such as the ADS122C04 for I2C and the ADS122U04 for UART communication.

    Best regards,

    Bob B