(ADuM14x)How to calculate the supply current when each channel's duty and frequency are not same.

Hi !

I already asked about the supply current about ADuM14x.

(ADuM140E1)Supply current. 

I want to make sure about it.

At the past thread, it is possible to calculate the supply current if all channel's frequency and duty are same.

But if our customer use this device with not same frequency and duty for each channel, the can not calculate the supply current.

So my questions are these.

Q1)

To calculate the supply current, I made new formula.

ADuM140
IDD1 = IDD1(Q) + (2.8mA * D_A + 0.01mA/Mbps * F_A)

                           + (2.8mA * D_B + 0.01mA/Mbps * F_B)

                           + (2.8mA * D_C + 0.01mA/Mbps * F_C)

                           + (2.8mA * D_D + 0.01mA/Mbps * F_D)
IDD2 = IDD2(Q) + (0.02mA/Mbps * F_A)

                           + (0.02mA/Mbps * F_B)

                           + (0.02mA/Mbps * F_C)

                           + (0.02mA/Mbps * F_D)

ADuM141
IDD1 = IDD1(Q) + (2.8mA * D_A + 0.01mA/Mbps * F_A)

                           + (2.8mA * D_B + 0.01mA/Mbps * F_B)

                           + (2.8mA * D_C + 0.01mA/Mbps * F_C)

                           + (0.02mA/Mbps * F_D)
IDD2 = IDD2(Q) + (0.02mA/Mbps * F_A)

                           + (0.02mA/Mbps * F_B)

                           + (0.02mA/Mbps * F_C)

                           + (3.4mA * D_D + 0.01mA/Mbps * F_D)

ADuM142
IDD1 = IDD1(Q) + (2.8mA * D_A + 0.01mA/Mbps * F_A)

                           + (2.8mA * D_B + 0.01mA/Mbps * F_B)

                           + (0.02mA/Mbps * F_C)

                           + (0.02mA/Mbps * F_D)
IDD2 = IDD2(Q) + (0.02mA/Mbps * F_A)

                           + (0.02mA/Mbps * F_B)

                           + (3.4mA * D_D + 0.01mA/Mbps * F_C)

                           + (3.4mA * D_D + 0.01mA/Mbps * F_D)

* D_A = Duty for A channel input
* F_A = Frequency for A channel input
* D_B = Duty for B channel input
* F_B = Frequency for B channel input
* D_C = Duty for C channel input
* F_C = Frequency for C channel input
* D_D = Duty for D channel input
* F_D = Frequency for D channel input

Are these formula correct?

Q2)

If these formula correct, I want ask one more thing.

I think our customer can calculate typical value with this.

But cannot calculate the maximum value because there are no maximum specification for these value.

Is it very difficult to calculate the maximum value?

I think ADI do the production test for 0-50-100% only so I think it is very difficult to calculate the maximum value.

Best regards

Kawa

Parents
  • Kawa-san:

    We looked at your formulas and this is how it should be:

    I don’t think it is right to put negative sign. You should instead use (1 – duty cycle ) to calculate how much the TX will draw current from supply.

     

    The correct formula should be like this:

    ADuM140E/D1 IDD1 = IDD1(Q) + (2.8mA * (1- D_A) + 0.01mA/Mbps * F_A)

                               + (2.8mA * (1- D_B) + 0.01mA/Mbps * F_B)

                               + (2.8mA * (1- D_C) + 0.01mA/Mbps * F_C)

                                          + (2.8mA * (1- D_D) + 0.01mA/Mbps * F_D)

    Regards, Brian

Reply
  • Kawa-san:

    We looked at your formulas and this is how it should be:

    I don’t think it is right to put negative sign. You should instead use (1 – duty cycle ) to calculate how much the TX will draw current from supply.

     

    The correct formula should be like this:

    ADuM140E/D1 IDD1 = IDD1(Q) + (2.8mA * (1- D_A) + 0.01mA/Mbps * F_A)

                               + (2.8mA * (1- D_B) + 0.01mA/Mbps * F_B)

                               + (2.8mA * (1- D_C) + 0.01mA/Mbps * F_C)

                                          + (2.8mA * (1- D_D) + 0.01mA/Mbps * F_D)

    Regards, Brian

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