Apologies for the delay in this response. I meant to send this response to you earlier, but it seems it was stored in my drafts. Thank you for following up.
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MP5031 with MP2491C:
a. Yes, all you would need to do is change the voltage divider to ensure the output voltage of the MP2491C and your system should be powered up. Although the only drawback with this option is that the MP5031 wouldn’t receive I2C data from this. If that is fine with you, then this should be a functional solution. -
MP5031 with MP4255
a. Yes, combining these rails together would yield you up to 6A total. Setting the output current of each of these rails at 2.5A and combining to 5A given Vout = 20V should yield you 100W. You would send and receive data via I2C with this option. -
Other DC/DC Products
a. This is a good question that would also apply to the MP2491C and for any other DC/DC converter that works with your application. Reading into the datasheet, the MP5031 would just have to be in I2C slave mode to disable I2C where I2C_MODE is connected to VCC. This would effectively disable any status messages or commands delivered or received by I2C. But if this is not needed for your application, then this is all you would need to do. -
MPQ4242
a. This is true, all reference designs in the datasheet are configured to the input of 9 - 16V. However, the part is capable of receiving an input of up to 36V as the maximum recommended voltage with 20V x 5A = 100W at the peak output.
b. Correct, to get this part working with 20V @ 5A, I2C programming would be required.
