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AM26LV31: AM26LV31's Icc vs AM26LV31E's Icc

Noriyuki Takahashi
Genius 11360 points
Part Number: AM26LV31


Hi team,

Are there any differences between AM26LV31's Icc and AM26LV31E's Icc?

Looking at  AM26LV31E datasheet, there are figure 1 and figure 2 for Icc, but there are no figures in AM26LV31.

Could you also estimate each Icc at the below condition?

Vcc = 3.3V

4ch

Data rate:5MHz

Regards,

Noriyuki Takahashi

  • 0
    TI__Mastermind 26836 points

    Takahashi-san,

    These two devices are functionally similar but not perfectly identical. Check out Parker's answer to another E2E question a few months ago: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1106825/am26lv31e-are-the-e-versions-of-am26lv3x-compatible-with-the-non-e-versions

    That being said, they should follow very closely. I would imagine they fall within any reasonable range of error.

    Also, keep in mind that the curves you point out are typical characteristics - the actual performance of a particular device will likely vary from exactly the numbers you see on those figures.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    TI__Genius 11360 points

    Danny

    Noriyuki Takahashi said:

    Could you also estimate each Icc at the below condition?

    Vcc = 3.3V

    4ch

    Data rate:5MHz

    Could you also give any comments on the question?

    Regards,

    Noriyuki Takahashi

  • +1 in reply to Noriyuki Takahashi
    TI__Guru 53082 points

    Hi Noriyuki,

    Is your datarate 5Mbps or 10Mbps (the frequency is half the data rate and this impacts the final measurement)

    Sorry for the delay.

    They could have different ICC's,

    Please see app note section 5 (and potentially 4)  for how to estimate power consumption - https://www.ti.com/lit/an/snoa233b/snoa233b.pdf

    In general the power consumption is something that is going to vary system to system as there are multiple factors that will determine this. 

    1. In general to estimate total current needed the linear approximation is: ICC_total = ICC + I_out.  For these devices we have a Cpd value - on both devices this is 160pF - since you have a frequency component the ICC_total equation can change to:

    I am assuming that the data rate is 10Mbps and the frequency is 5MHz - if this is not the case the numbers in the equation will be slightly different. 

    ICC_total = IS + I_out --> where IS = ICC + f * VCC * Cpd --> for both of the devices this is the same at IS = 100uA + 5MHz *3.3V*160pF = 2.74mA 

    I_out is the current that is sourced from the device (and therefore ICC_total). For these devices the leakage current is negligible (it is in uA range which is going to be << than the I_out current)  from all the high impedance input pins (logic pins) so the only ones of real concern are the  differential outputs. Then the current sourced is the differential voltage divided by the differential load (for this device and RS-422 standard the load is 100 Ohms).

    The Non-"E" device has a standard VOD of 1.5V with a load of 100 Ohms at 4 channels that is a current of 60mA. So the non-"E" device would have an approximate ICC_total = 62.74mA.

    The "E" device has a standard VOD of 2.6V with a load of 100 Ohms at 4 channels is a current of 104mA so giving an apprx. ICC_total = 106.74mA.

    Figure 1 in both datasheets gives a typical power curve - the non-E datasheet only shows a no-load condition and the "E" datasheet gives a no-load and a few loading conditions as well.

    There are 3 large caveats here:

    1. capacitance, cabling, common mode loading / bus loading, and other device on bus will also impact the loading and therefore the actual current consumption of the system. So characterization by customer in customer specific system is still recommended as the estimates I gave above are just in line what you may see - but due to the multiple factors that impact this final value it is hard for me to give a highly accurate number and it is just a ball-park estimation.

    2. If loading is different then the current consumption will be different. I was also using typical VOD values at 100 Ohm loads - this can vary and so will the power needs of the system. As with many things temperature is also going to impact these values.

    3. The approximation I made is mostly linear - in reality there is non-linearity in this measurement - at 5MHz (10Mbps) its still relatively linear but the higher the frequency the more likely there will be deviations due to non-linearity of the system. 

     

    Please let me know if you have any other questions and I will see what I can do!

    Best,

    Parker Dodson