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PGA302: Calculate ENOB Example

user6333832
Prodigy 40 points
Part Number: PGA302

Hello TI Team,

How can I calculate the ENOB for the PGA302. For the different gain settings (1.33; 2; 4; 10; 20; 40; 100) I would need the corresponding enobs. Or give me a calculation example, I can't get by with the given formula!

With friendly regards

H.Härle

  • 0
    TI__Mastermind 31655 points

    Hello Mr. Harle,

    The ADC error is at its worst at the highest gain of 200, which is where the ENOB is specified in the datasheet, so the ENOB of the other gain settings will be greater than 11.4. Note that this is ENOB of the raw, uncalibrated ADC output, so it is truly the worst case scenario. The procedure used to determine the ENOB is detailed in the specification as well:

    Procedure to calculate ENOB:

    1. VDD = 5 V

    2. Temperature = –40°C, 25°C, 125°C, 150°C

    3. Connect 5-KΩ, Zero TC bridge to the pressure input pins device with near zero differential voltage

    4. Set P GAIN = 200 V/V

    5. Set ADC sample period to 96 µS

    6. Set input MUX to pressure channel

    7. Measure ADC

    8. Calculate ENOB using the formula: 20log10((32768/2/√2)/(ADC code rms))/6.02

    Unfortunately I don't have any additional characterization information available or example data to provide. The only option aside from the procedure outlined above would be to measure the SNR of the PGA302's ADC output and calculate the ENOB with the standard formula (ENOB = (SNR - 1.76)/6.02.

    Regards,