DRV8718-Q1: PWM duty cycle problem

Hi Colt,

What does the output waveform look like when you say it doesn't reach 50 %. Give me 24 hours to look into this and get back to you.

Best,

Keerthi 

hi Keerthivasan,

the out put look like is OK, any progress of this problem.

Hi Colt, 

The MOSFET turn-on response usually looks like (From the smart gate drive app note). This can be clearly seen in the second waveform. One reason why the first waveform has similar features, but the initial ramp is a lot longer is that there might be current already in the system (like through the freewheeling diodes) I would like to know the load conditions or if there is any current on the output at all.

Just to clarify does the output waveform have 50 % duty cycle. Can this be confirmed.

Best,

Keerthi 

hi Keerthivasan

first, the output waveform have 50% duty cycle.

second, now customer have another question: when use low side control, the Waveform of GL will have a voltage step, such as the following figure red circle.

and when change the PWM IN duty cycle, the voltage step also change, the max voltage step is about 1.2V. could you help analysis this problem.

if possible, i want to loop you in the customer mail, you can directly talk with customer about this problem.

Hello Colt, 

Give me 24 hours to look into this and get back to you.

Best,

Keerthi 

Hello Colt,

Can you tell me more about their IDRIVE settings as well if they are any using any smart gate drive settings:

I will try to see if I can recreate this in lab and give you an update by the end of this week.

Best,

Keerthi