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OPA211: Worst case quiescent current

Danilo A.
Mastermind 24715 points
Part Number: OPA211

Hi Team,

The datasheet provides information on the maximum quiescent current over the whole supply range pf OPA211. A customer would like to know if the device is powered from ±2.3V, what is the worst case it could draw current from the operating temperature range of -55C to 150C?

Regards,

Danilo

  • 0
    TI__Mastermind 48076 points

    Hi Danio,

    Q: What is the worst case it could draw current from the operating temperature range of -55C to 150C?

    There is no specific data published in OPA211 at 150C. However, if I use OPA211-HT as comparison, the Iq per channel is shown at approx. 7.5mA. So I would use Iq = 7.5mA/channel as the worst case scenario from -55C to 150C. 

    If you have additional questions, please let us know. 

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    TI__Mastermind 24715 points

    Hi Raymond,

    Thank you for your response. The 7.5mA maximum current consumption of OPA211-HT is higher than the max current of OPA211 at 6mA which is probably at +/-18V. The customer's concern is the worst case current consumption at ±2.3V. Do we have other similar device we can reference to?

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Mastermind 48076 points

    Hi Danilo,

    Previously, Iq = 7.5mA figure is based on experimental data from OPA211-HT at Ta = 210C. 

    If we perform the derivation of the worst case in Iq figure at 150C based on the Figure 20 and Figure 21 of the OPA211 datasheet, the calculated worst Iq figure is 6.404mA  at 150C at Vs = 4.6Vdc (+/-2.3Vdc). Please be aware that TI makes no assurance about anything that isn't specifically stated in the datasheet. 

    Here is how the worst figure of Iq = 6.43mA at Vs= +/-2.3Vdc is derived at 150C, see assumption 1 and 2. 

    1. Figure 20 below is shown that Iq vs. temperature behaves linearly from -55C to 150C, where Vs = 36V or (+/-18V)

    2. Figure 21 is shown the Iq vs. Vs behaves linearly from Vs=4V to 36V at 25C. Also assume that the same slope of Iq vs. Vs will be maintained at 150C.

    From Figure 20, the slope of Iq vs. temperature is extracted with the two points (-25C, 3mA) and (137.5C, 5mA). Instead of using the nominal value, I used the worst case figure found in OPA211's table, where (25C, 3.6mA) and (125C, 6mA) The slope delta(Iq)/delta(T) = 2.4mA/100C=0.024mA/C. The intercept is calculated to be 3mA. At 150C, Iq = 6.6mA is extrapolated with Vs = 36V.  

    From Figure 21, the slope of Iq vs. Vs is calculated to be 6.25e-3 mV/Vs using the following 2 coordinates, (36Vs, 3.6mA) and (4Vs, 3.4mA) at 25C. From Figure 20, Iq=6.6mA at  Vs = 36V at 150C. Based on the assumption 2, the intercept is calculated to be 6.375mA at 150C. If  Vs = 4.6V (+/-2.3V), Iq = 6.404 mA  is extrapolated at 150C. 

    If you have additional questions, please let me know. I could do rough estimation, but I think that the extrapolated worst Iq figures should be fairly close to the real world scenario.  

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    TI__Mastermind 24715 points

    Hi Raymond,

    Thank you very much for your effort to answer this challenging question. I understand that TI makes no assurance about any information that isn't specifically stated in the datasheet. We will update the customer and will let you know if he has further inquiries.

    Regards,

    Danilo