DRV8243-Q1: Open load fault misreporting

Scarlett Cao

Part Number: DRV8243-Q1

Hi team,

My customer is using DRV8243-Q1, and found when there's motor load applied, the motor driver IC still report open load fault. They are using the high side recirculation. And I asked them to probe the switching OUTB and VM waveform as below. As we can see the OUTB voltage spike is just slightly higher than VM, so we think it is reasonable to report OL because they didn't observed the diode voltage drop ~0.9V.

CH1 OUTB CH3 VM

l also checked their load current, it is higher than the pull down current.

Could you please kindly help share why there's no diode voltage drop? Any device to debug this open load fault misreporting issue?

Thank you

Scarlett

over 2 years ago

0 Shinya Morita over 2 years ago

TI__Mastermind 44855 points

Hi Scarlett,

Thank you for your questions.

1) Diode recirculation should happen only dead time period(tDEAD). I am not sure their scope is capturing for such a short period. So it is hard to judge they do not have voltage drop or not.

2) If they have some external circuit, it may remove diode drop. If no motor current, no voltage drop.

3) Best way to to capture VM and OUT1/2 waveform trigger with nFAULT. Somewhere OLA could be detected, but no more OLA condition after it.

regards

Shinya Morita

0 Scarlett Cao over 2 years ago in reply to Shinya Morita

TI__Expert 4030 points

Hi Morita-san,

Sorry I don't quite understand your point 3, what do you mean by no more OLA condition after it? I asked customer the open load fault is always reported during driving.

I also asked customer to share the zoom out waveform, seems the measured diode voltage is only 600mV.