Q:
When doing margin high/low test, which SLOPE should I use? Should I use positive SLOPE for margin high and negative SLOPE for margin low? Or the initial PWM level and the target margin high/low voltage (or percentage) also need to be considered.
Ans:
Use a positive slope when the PWM is directly driving the reference voltage of a power supply. Use a negative slope when the PWM is injected into the power supply's feedback pin.
You just need to use one. Usually PWM is injected into the power supply’s feedback pin, for example, this is the case on our evkit.
So when I test the margining function on our Evkit, I just use negative slope and then select margin high/margin low in OPERATION command (01h) for the margining test.