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

Hi !

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.

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)

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)

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

• Hi Brian-san

I understood.

I want to confirm few more things.

Q1)

ADuM14x has wide power supply range.

So IDD(Q) will change.

For example when our customer use ADuM14x at 5V, the specification will be this.

Is my understanding correct?

Q2)

I thought that the formulas will change if our customer use E0 or E1.

Therefore, if accurate to write, the formulas will be this.

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)

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)

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)

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)

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)

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

* IDDx(Q) = supply current when input is "0"

Is my understanding correct?

Best regards

Kawa

• Kawa-san: We reviewed the formulas and they look good.  I asked the designer also about the max spec but unfortunately we don't have a max limit for those supply current values.

Regards, Brian

• Hi Brian-san

Thank you for your support every day.

Can you help about my question?

Best regards

Kawa

• Hi Brian-san

I understood.

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)

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

+ (0.02mA/Mbps * F_B)

+ (0.02mA/Mbps * F_C)

+ (0.02mA/Mbps * F_D)

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)

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)

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

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_C + 0.01mA/Mbps * F_C)

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

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

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

+ (3.4mA * (1 - 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

Best regards

Kawa

• 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