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ADP7142 Configuration with 24 - 5V

Question asked by Zartagal on Oct 23, 2014
Latest reply on Oct 23, 2014 by power-layout-guy

Hi Forum Team,

I have a doubt about the recommended configuration for the ADP7142 chip. The configuration I made with the Excel tool of this chip, after it was recommended from ADISimPower, includes an input resistance between the input 24V and the Vin of the chip.

 

It indicates to use 4 resistors of 402 Ohm. I'm not really sure if they are 4 resistors of 402 Ohm or just 4 resistors of around 100 Ohm to get in total around 400 Ohm.

 

I made the calculation for:

 

Vin = 24V (max and min)

Vout = 5V

Iout = 60mA max

 

The first question is the refered. Do I have to use 4 resistors of 100 or 400 Ohm?

 

The second is about the functionality. I understand that you have to disipate part of the power in the resistors but with a 60mA over the 400 Ohm we have a voltage of around 24V. So my question: is the input current the same as the output current?

If not, how much is the current in the input?

 

THanks in advance,

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