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ADS1015: vs TLA2024

Allan Fan
Expert 7780 points

Part Number: ADS1015
Other Parts Discussed in Thread: TLA2024

Tool/software:

Hi experts,

May I learn from you what are main differences between ADS1015 and TLA2024 except temp range? Customer would like to choose a solution for temp sensing with NTC.

I can't tell from the our cross. 

TLV2024 Ta 85 is good enough for customer.

Thanks,

Allan

  • 0
    TI__Guru 58951 points

    Hi Allan Fan,

    Can you please respond to my request in the Notes section of the Thread Tracking Toolkit?

    -Bryan

  • 0
    Prodigy 70 points

    Hi experts,

    We'd like to know how to calculate the overall tolerance that includes the ADC.

    Assume we plan to pull up to 3.3V (with a tolerance of ±3%) using a 100kΩ pull-up resistor (±1%), and a 10kΩ NTC thermistor (±1%) connected to the ADC channel of the TLV2024.

    For the external circuit tolerance, we derived the following table (0.3V ± 14mV):

      Voltage (V)
    ADC max 0.320774519
    ADC min 0.279860234
    ADC Typical 0.3

    So how do we calculate the overall tolerance after including the ADC?

  • 0 in reply to Ping-Han Lee
    Prodigy 70 points

    Hi Experts,

    The total RSS error of the TLV2024 for an FSR of ±4.096 and a temperature range of -25°C to 90°C should be ±6.3mV? And for FSR of ±2.048 should be ±3.1mV?

      Voltage (V) Voltage (V)
    Temperature range  -25oC to 90oC  -25oC to 90oC
    FSR 4.096 2.048
    INL 0.002 0.001
    offset error 0.002 0.001
    Gain error 0.002048 0.001024
    Gain drift 0.0047104 0.0023552
    Offset drift 0.0023 0.00115
    RSS error 0.006298585 0.003149292
  • 0 in reply to Ping-Han Lee
    TI__Guru 58951 points

    Hi Ping-Han Lee,

    How did you calculate the individual errors in your list?

    I am not saying they are right or wrong, it would just be helpful to see the calculations to confirm they are correct

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 70 points

    Hi Bryan,

    Under conditions  FSR = 4..096, temperature range from -25 to 90 C:

    Specification Calculation
    Integral nonlinearity 1 LSB 4.096*2/2^12
    Offset error  +/- 1 LSB 4.096*2/2^12
    Gain error 0.05% 4.906*0.0005
    Gain drift 10ppm/C 10*10^-6*4.096*(25+90)
    Offset drift 0.01 LSB/C (90+25)*0.02*0.01
  • 0 in reply to Ping-Han Lee
    Prodigy 70 points

    Correct gain error calculation

    Specification Calculation
    Integral nonlinearity 1 LSB 4.096*2/2^12
    Offset error  +/- 1 LSB 4.096*2/2^12
    Gain error 0.05% 4.096*0.0005
    Gain drift 10ppm/C 10*10^-6*4.096*(25+90)
    Offset drift 0.01 LSB/C (90+25)*0.02*0.01
  • 0 in reply to Ping-Han Lee
    TI__Guru 58951 points

    Hi Ping-Han Lee,

    Your calculations look correct

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 70 points

    Hi Bryan,

    Thanks for reply.

    Should it be reasonable to calculate the overall tolerance of the ADC using the RSS method (|tolerance| = √(A² + B² + C² + …))? The total RSS error of the TLV2024 for an FSR of ±4.096V and a temperature range of -25°C to 90°C should be about ±6.3mV, and for an FSR of ±2.048V, it should be about ±3.1mV?

    Also, because the TLV2024 only has one PGA, this means that if we have different pull-up voltages on each channel, it would be best to select the corresponding FSR. For example, a 1.8V pull-up should use an FSR of ±2.048V, and a 3.3V pull-up should use ±4.096V?

    And what is the difference between the ADS1015 and TLV2024, other than the operational temperature range?

    Ping-Han Lee

  • 0 in reply to Ping-Han Lee
    TI__Guru 58951 points

    Hi Ping-Han Lee,

    Yes, this is a common way of estimating total unadjusted error (TUE)

    Ping-Han Lee said:
    For example, a 1.8V pull-up should use an FSR of ±2.048V, and a 3.3V pull-up should use ±4.096V?

    Yes, you can change the FSR to match the input signal, if desired.

    Ping-Han Lee said:
    And what is the difference between the ADS1015 and TLV2024, other than the operational temperature range?

    I don't have a side by side comparison, but generally the ADS1015 includes a few more specifications, while some specifications have a guaranteed min/max, whereas the TLA2024 does not. The ADS1015 also has a comparator, while the TLA2024 does not

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 70 points

    Hi Bryan,

    We consider to use ADS1015IDGSR, so what is the overall error that ADC can have base on following conditions:

    1. FSR of ±4.096V

    2. -25°C to 85°C

    As described in the email, we used ADS1015 mainly for NTC application, we target to have the temperature tolerance of +/- 3°C 

  • 0 in reply to Ping-Han Lee
    Prodigy 70 points

    Add other conditions:

    3. VDD = 3.3V

    4. 4 channels all single ended (3x for NTC application)

    5. NTC used Murata NCP15XH103F03RC (+/- 1% NTC)

    6. Please refer to attached excel from email for calculation.

  • 0 in reply to Ping-Han Lee
    TI__Guru 58951 points

    Hi Ping-Han Lee,

    This issue is being resolved offline

    -Bryan