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TLE2022AM: Output voltage during No load

Raghavendra Ramachandra
Prodigy 20 points
Part Number: TLE2022AM

Please find the circuit attached, we are seeing variation in output voltage at different temperatures. Though the variation is less, it is not acceptable for our requirement.

For a 2V input and Single Supply of 5V, No load condition. The measure output voltage at different temperature is as follows: 

Ambient (25C) 2.00328 (1)

Cold (-55C) 1.99936

Hot (110C) 2.00075

For a 2V input and Dual Supply of +/-15V, No load condition. The measure output voltage at different temperature is as follows: 

Ambient (25C) 2.00105 (2)

Cold (-55C) 2.00083

Hot (110C) 2.00046

What could be the reason for variation in ambient values, comparing (1) and (2)

  • 0
    Guru 140200 points

    Hi,

    I see two issues:

    1. A high source impedance (not shown in your schematic) could be responsible for the offset voltage changes because the input bias current is temperature dependent.

    2. Your circuit is instable. You cannot run a dual feedback stabilized OPAmp without the load the OPAmp was compensated for. This can cause stability issues:

    ragh_tle2022.TSC

    The OPAmp can be stabilized with these two changes:

    Kai

  • 0
    TI__Mastermind 49821 points

    Hi Raghavendra,

    Raghavendra Ramachandra said:
    What could be the reason for variation in ambient values, comparing (1) and (2)

    My guess is that this part may not meet your requirements (taking absolute delta figures). 

    1. Vos is up to 0.5mVmax with Gain = 1 at 25C per the datasheet's configuration. 

    2. Temperature coefficient is approx. 2uV/C (typical) --> for 110 - (-55) = 165C delta, it will shift up to 2uV/C * 165 = 330uV = 0.330 mV in the entire range. 

    a. Per your data from part2 to part1 at 25C: Delta is 2.000328 - 2.00105 = 0.722 mV

    b. Per your data from part2 to part1 at -55C: the Vout spread is approx. 2.00083 - 1.99936 =1.47 mV

    c. Per your data from part2 to part1 at 110C: Vout delta is approx. 2.00075 - 2.00046 = 0.290 mV

    d. From -55C to 25C: temperature drift contribution is approx. 2uV/C*80C = 0.16 mV

    e. From 25C to 110C: temperature drift contribution is approx. 2uV/C * 85 = 0.17 mV

    Although the specification of TLE2022AM is measured differently from your setup (shown below), these errors will reflect in the accuracy of the operating conditions and the part. 

    What are the application accuracy requirements? You may consider to use zero drift precision op amps (low Vos (5-10uV) and ultra low temperature drift coefficient) to construct the current source (my guess that this is what you have). 

    TLE2021 Temp Issue 03162023.TSC

    If you have additional questions, please let us know. 

    Best,

    Raymond