MC1584 dropout voltage

I bought a few MC1584 modules off Amazon.
Before I go to the trouble of trying them, I looked at the specs and it is not clear to me what the dropout voltage is - to me this is the minimum input voltage specified to guarantee the desired output voltage.
I require 6.87V and my intended input voltage is generated by two 18650 cells that start at 8.4V (sum) but drop down obviously as they deplete themselves from the load. If there is another approach recommended I’d like to see it.

Hi barryklein,

Thank you for using the MPS Technical Forum. First, did you mean to say the MP1584? The Vin operating range for this device is 4.5V to 28V. Second, using this step-down converter, Vout of 6.87V, and assuming an operable Vin of 6V to 8.4V from the cells before recharging, I was wondering if you might need a Buck-Boost rather than just a Buck?

Ahhhh you’re right!
Open to your suggestions, hoping there is a prebuilt on Amazon…

The ideal output voltage is 6.86V, current is 800mA. The load has an over voltage shutdown of 7.9V. It has a low battery warning close to 6V.

Hi barryklein,

I would suggest looking at the MP8860 (https://www.monolithicpower.com/en/mp8860.html)
This is a 2.8V-22V, 1A synchronous buck-boost with I2C interface.

For further assistance and/or to better focus on your application with our FAE team, feel free to contact MPS Now (https://www.monolithicpower.com/en/support/mps-now.html)