Hi Expert
My customer need the test issue as below show:
firstly this device used in DLP LED driver and customer schematic as below:
in their test, they doesn't input PWM, just input 0.66V to IADJ
when input voltage =12V everything is okay but when their reduce input to 8.2V, the PGATE will keep contrast voltage(about 7V)
test waveform as below:
1. below picture is normal waveform:
output current is 5A the green is PGATE and the red is output current
2. this picture is show that input voltage form 12V to 8V. the green is PGATE and the red is output current.
you can see when input voltage reduce to 8V, PGATE will keep low voltage and PFET will keep open.
3. the picture is show output voltage and output current when input is 8V , you can see output current about 6.3A and max is about 6.6A
.
in my understand:
customer Imax=Vadj/(5*Rsns)=6.6A: output current is about 6.3A so I think this current touched Lmax
when input reduce to 8V and the same time output is 7V, I think maybe the condition like near dropout.
so we need to change the parameters for letting circuit work in 8V or lower voltage.
could you please help to resolve this issue?
