Hello team,

I have a customer who is using MC34704 with i.MX25.

And 5V is supplied into VIN of MC34704, and REG2,3,4 are used on his board.

In that case, where can I find the description which can be helpful to estimate the current flowing into PVIN2,3,4(VIN)?

Thanks,

Miyamoto

The estimation is quite simple in that case. Let's consider it on "per regulator" basis.

1. First, calculate the power that the regulator 'x' provides to a load: Pout_x = Vout_x * Iout_x, where Pout_x is the output power of a regulator 'x', Vout_x and Iout_x - its output voltage and current, respectively.

2. Then, assuming the typical conversion efficiency of regulator as 80% (denoted in the data sheet), multiply the Pout_x by 1.25 (1/0.8) to calculate the power that the regulator 'x' consumes on its input: Pin_x = Pout_x *1.25 .

3. Now, knowing the input power and input voltage, we can calculate the input current: Iin_x = Pin_x / Vin_x .

Assuming the input voltage of 5V, the final calculation for a regulator 'x' is as follows:

Iin_x = (Vout_x * Iout_x * 1.25) / 5 = (Vout_x * Iout_x) / 4 .

Have a great day,

Artur

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