MP4248 - Fixed 24V output using FB resistor divider without I2C

DC-DC Power Converters
1

Hi,

I am considering the MP4248 for a rover application with the following parameters:

  • Input: 18V–34V (unregulated battery)
  • Output: 24V at 3A (fixed, 72W)
  • Part number under consideration: MP4248GQV-0011

The output voltage will never change, so I do not need dynamic voltage adjustment or I2C communication. My plan is to use the default MP4248GQV-0011 OTP configuration and set the output voltage using only the external FB resistor divider.

However, I ran into a concern. The default VREF is 0.5V. To get 24V output, the required feedback ratio would be:

VOUT / VREF = 24V / 0.5V = 48

The datasheet (pages 28–29) recommends a feedback ratio of 10 or 15 and states that VOUT may be “abnormal” when outside the valid range for those ratios.

My questions:

  1. Can the MP4248 operate reliably using only the default OTP settings and the FB resistor divider, with no I2C communication at all?

  2. Is a feedback ratio of 48 supported, or will this cause issues with accuracy, OVP thresholds, or other internal functions?

  3. If a ratio of 48 is not recommended, is a one-time I2C write at startup the only way to raise VREF and use a lower ratio?

Thanks for your help!

2

Hi @cnune052 ,

Yes, you can modify the feedback resistors to achieve 24V without I2C. This was tested with the below formula, and the device operated as expected:

Vout = Vref * ( (R1+R2) / R2 )

Recommended to use R2 = 10kOhms.

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Thanks,
Rubas

3

Thank you very much for the quick response!