DRV8303: voltage drop at GVDD after EN high

Olrik Maier

Part Number: DRV8303

HI,

my customer is facing some issues with the DRV8303.

~ 20ms after switching EN_Gate to high the DRV8303 shows a voltage drop at GVDD (green voltage in the attached scopeplots).

This happen before a MOSFET is switched on (see second scopeplot). At low battery voltage of ~15V the GVDD voltage can drop down below 7V.

What is the issue for that ?

The DRV8303 showed from time to time an undervoltage flag in the failure memory for GVDD.

Capacity between GVDD and GND ~ 10uF MLCC

Best wishes,

Olrik

over 4 years ago

0 Adam Sidelsky over 4 years ago

TI__Guru 61200 points

Olrik,

I didn't see the image as mentioned, please reupload it.

Regards,

-Adam

0 Olrik Maier over 4 years ago in reply to Adam Sidelsky

TI__Expert 4630 points

Hi Adam,

pls see attached the missing plots.

Best wishes,

Olrik

0 Adam Sidelsky over 4 years ago in reply to Olrik Maier

TI__Guru 61200 points

Olrik,

Checking the phase current ("phasenstrom") will not correlate with the gate signals turning on. Can you repeat the plot above but showing the High side and Lows side gate of one phase?

Regards,

-Adam

0 Olrik Maier over 4 years ago in reply to Adam Sidelsky

TI__Expert 4630 points

HI Adam,

I have done some additional measurements and yes, we have here two short switch on pulses on GL_C, followed by two switch on pulses on GH_C. These pulses are not during the same time. Also no other MOSFET is switched on in this period of time. The first pulse should be as long as the 2^nd one but I think due to the drop in GVDD the gate will be switched off again.

Nevertheless we can see this drop of GVDD here. During normal operation this drop cannot be observed. A delay of additional 10 ms between start up and switching this pattern also do not help.

Measurements by email

Best wishes,

Olrik

0 Adam Sidelsky over 4 years ago in reply to Olrik Maier

TI__Guru 61200 points

Olrik,

Since this is being handled by email and the issue is on hold, I am closing this thread as it cannot stay open and inactive.

Regards,

-Adam

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DRV8303: voltage drop at GVDD after EN high