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ISO7021: Supply current consumption Icc1 has big difference to Icc2

user1312478
Prodigy 60 points
Part Number: ISO7021

hello,

i measured the supply current consumption with 100KHz signal (duty cycle 50%), the input signal into INA (PIN7), connect OUTA (PIN2) and INB (PIN3) directly, the VCC2 current consumption only 31.8uA, but the VCC1 current about 290uA. In datasheet, the current for VCC1 and VCC2 are same for one scenario. i don't know why two supplies have big different current consumption? VCC1 and VCC2 are 3.3v.

In datasheet page 10, Supply current - AC signal (100Kbps), what is the means no load? Thanks!

  • 0
    TI__Guru 53855 points

    Hi,

    Thank you for your interest in ISO7021.

    In the datasheet page 10, by no load we mean nothing is connected to the output pins. i.e., both OUTA and OUTB are floating and are not connected to anything. I see that you have connected OUTA (pin2) back to INB (pin3) while the 100kHz input signal is applied to INA (pin7). Since OUTA has INB connected as load (~2pF of capacitance load) while OUTB doesn't have any load connected, it is expected to see VCC1 current to be higher than VCC2. This is the reason you are seeing the difference.

    Please disconnect OUTA connection to INB and apply a separate 100kHz signal to INB then measure again, you should see similar current consumption for both VCC1 and VCC2. Once you do the measurements, please do let us know your observations Thanks.

    Regards,
    Koteshwar Rao