user6481287 

First, the TPSM8D6B24 is a 25A rated converter, the testing labels show 1A to 30A to 1A.  For a 30A output, the TPSM8D6C24 converter should be use, or the two-channels of of the TPSM8D6B24 can be connected into a 2-phase design with each phase supporting 1/2 of the loading current.

The output voltage overshoot is generally determined by the excess energy stored in the inductor, which must be discharged by operating the converter at 0% duty cycle.  This produces an overshoot voltage of:

ΔIout^2 x L  / (Vout x Cout) 

The internal inductor for the TPSM8D6B24 is 470nH

For a 30A to 1A transient, ΔIout is 29A

Cout for the TPSM8D6B24EVM-2V0 is 1571μF

For Vout = 0.8V, this produces an output voltage overshoot of 314mV. 

For a lower output voltage overshoot with Vout = 0.8V, you'll need one of the following options

Additional Output voltage capacitance  (as output capacitance is added, the VLOOP gain can be increased from 4x to 8x (See below)

Configure the TPSM8D6B24 into a 2-phase configuration (each phase operates with half of the current, to ΔIout will be half for each inductor)

Switch to the TPSM8D6C24 which uses a 220nH inductor

When the output voltage is increased and the internal divider programmed by VOUT_SCALE_LOOP is changed from 0.5 to 0.25 and 0.125, the loop gain is reduced by the feedback divider, resulting in large output voltage changes.  That can be countered by changing the VLOOP selection through the MSEL1 pin programming.

ILOOP = 4, VLOOP = 8 for 550kHz can be selected through PMBus programming via the TI FUSION GUI or by changing R24 or R35 depending on if you are testing channel A or channel B of the evaluation module, from 14.7kΩ to 17.8kΩ

The overshoot during the load increase response for the higher output voltages is unusual and suggests that there might be excessive inductance between the evaluation module output and the load, such as from longer wires connecting the evaluation module to an electronic load, with the remote sense connected to the load after this inductance.  This excessive inductance can result an significant overshoot at the output of the EVM before that inductance as the converter attempts to overcome the voltage drop across that inductance, overshoots the regulation point as the voltage drop across the inductance falls, and then recovers.

Make sure there is only 1 ground connection between the board under test and the oscilloscope.

Make sure there are no other "Earth" grounds connected to the board under test

If using the remote sense test points to connect the evaluation board to an electronic load, minimize external inductance by using short, heavy gauge wires to connect the evaluation board to the electronic load.  Or connect the remote sense to the output terminals of the evaluation board where the oscilloscope probes are connected.