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ADS1256: DAQ design

sarath M
Prodigy 60 points
Part Number: ADS1256
Other Parts Discussed in Thread: ADS125H02, PGA855, ADS127L21, DAC81401

HI TI, 

we are going to start new development of DAQ module, here are our requirements 

the DAQ system should support both voltage and temperature measurement

the Voltage input should be from ±0.10 V,±5.0 V±10.0 V, 0-5 V, 0-10V can you suggest a front end module or independent ADC with sampling rate of minimum 50k

and temperature wise it should accept both thermistor and thermocouple inputs, ADC can take these inputs directly, if ADC cannot accept these inputs directly suggest us  specialized chips for this operation

note: thermocouple- wide range (J K T S N E R B) and thermistor(5k to 100k)

suggest us a DAC for analog outputs (±5V, ±10V, 0-5V, 0-10V).

regards

Sarath

  • 0
    TI__Mastermind 46120 points

    Hello Sarath,

    Please take a look at the ADS125H02.  This ADC meets almost all of your requirements.  Maximum data rate is 40ksps, but it supports up to +/-20V inputs, and includes a PGA, reference, and current sources for use with RTD and Thermocouples.

    If you need higher speed, then I would suggest looking at the ADS127L21 and PGA855.  This will be a multi-device solution, but will provide the data rates and input ranges that you require.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    Prodigy 60 points

    Hello Keith,

    Thank you for your prompt response.

    Could you also recommend a DAC based on the output specifications I provided earlier (±5V, ±10V, 0-5V, 0-10V)? Each channel should support a maximum load current of 100mA. Additionally, the output from the DAC can be either a sine wave or a square wave (programmable options are acceptable). I'm curious about how this DAC will perform with capacitive or inductive loads. Will the waveform be distorted if connected to other types of loads?

    Best regards,
    Sarath

  • 0 in reply to sarath M
    TI__Mastermind 46120 points

    Hello Sarath,

    DAC81401 supports the voltage ranges you mentioned.  The DAC can be used to generate sinewaves, but you would need to stream data to the DAC from an MCU that generates the sinewave pattern.  You would also need to add a power amplifier to drive 100mA load currents; I do not think we have any DACs that can directly support this much current.

    If you have additional questions regarding a power-amp, I suggest you post a separate question covering your specific amplifier needs.

    Regards,
    Keith