TPS546D24AEVM: TPS546D24AEVM

Darshan Moodgal 

There are no required changes to the output decoupling capacitors or the compensation to convert from 2-phases to 1-phase.  The 2-phase output has sufficient output capacitance to stablize the 1-phase loop.

To fully utilize the available output capacitance, you can select a compensation code with 2x higher VLOOP due to the reduced current loop gain from the loss of 1-phase.

This will provide similar transient performance to the original 2-phase design for the same load step, compensating for the reduced forward transconductance with increased voltage loop gain.

The base EVM uses MSEL1 to AGND = 12.1kΩ (Resistor to Ground code 5) with no resistor to BP1V5 (Divider Code None).  Table 7-9 shows this selects Compensation Code 13 with ILOOP = 4 and VLOOP = 2.  Changing to Compensation Code 14 (ILOOP = 4, VLOOP = 4) is resistor to ground code 6 with no divider.  Table 7-17 shows this is a 14.7kΩ resistor to AGND (R21_P1)

Alternately, you can remove 1/2 of the output capacitors.

This will provide similar transient performance to the original 2-phase design for 1/2 the load step, leveraging the reduce forward transconductance to allow less output capacitance.

If removing capacitors, I would recommend removing the capacitors furthest from L1, working closer to L1 to provide the loop with the least parasitic inductance possible after removing the capacitors.