# Inquiry about Voltage Regulator

Hi,
We are designing a custom board, and the following specifications are our requirements:

1. Input Voltage Range: 30V to 100V.
2. Output Voltage: 24V.
3. Output Current: 1A .
Additionally, We have reviewed the MP9486GN-Z, but require clarification on how to determine the feedback resistor values, output capacitor value and output inductor value.
Regards,
Nitheesh

Hi Nitheesh,

MP9486 design equations are on page 13-14 on the DS.
If you need more headroom on the peak current, there is the MP9486A | 100V Input, 3.5A, Switching Current Limit Step-Down Converter | MPS (monolithicpower.com).

Regards,
Vinh Tran

Hi,
I already refer the datasheet, But i am bit confuse on output inductor and capacitor calculation. Feedback resistor’s calculation is fine.
Additionally, kindly clarify whether this IC gives 24V output or not when we adjust the feedback resistors.
Regards,
Nitheesh

Hi Nitheesh,

To calculate the inductor size, use the equation:

Where K is the coefficient for current ripple peak to peak.

For a basic start, you can try copying our EVB design: EV9486-N-00A | 1A,100V Wide Input Buck Converter EV Board | MPS (monolithicpower.com)

For 24V, it should be possible, but I would recommend using a device with a newer control scheme. If you are able to lower your current requirement, I would recommend the MP4581 | 100V, 0.8A Synchronous Buck Converter | MPS (monolithicpower.com)

24V

Regards,
Vinh Tran

Hi,
Thanks for your response.
I have reviewed the datasheet of MP4581 IC. We are now using the MP4581 in our custom board.
Additionally, we also have a 5V rail [5V OUTPUT] on our board. To achieve this, we are following the reference design provided in the datasheet for the 5V output. However, we are providing two different input voltages: sometimes 24V and sometimes 12V in the same circuit[Reference design in datasheet].
Could you please confirm whether both 12V and 24V inputs will result in a 5V output in that same circuit?
Regards,
Nitheesh