DRV8873HEVM: Issue

Alen Barisic

Part Number: DRV8873HEVM

Hi,

The DRV8873 EVM software was configured as shown in the attachment (evk gui.png).
Without load (with open output), the signal on the OUT1 looked good- see "without load.png".
With a 5 ohm resistance between VM and OUT1, the signal on the OUT1 looked also good- see "with 5ohm resisor between out1 and vm.png".
However, if I want to usea load between GND and OUT1, the duty cycle suddenly drops to 10% for no apparent reason - see "with 5ohm resisor between out1 and gnd.png".
From 0-10%, the duty cycle remains adjustable, but it can not be set higher than 10%.
Can you explain this behavior?

Best regards,

Alen

over 6 years ago

0 Alen Barisic over 6 years ago

TI__Intellectual 1300 points

0 Rick Duncan over 6 years ago in reply to Alen Barisic

TI__Guru** 114905 points

Hi Alen,

This behavior is probably intentional, although more information is needed to fully understand it.

Can you please attach a current probe and provide a scope capture of the current along with the voltage when the load is connected to GND?

Also please provide a screen capture of the register map page of the GUI.

You may be experiencing the current regulation feature. Please refer to section 7.3.1.3 of the datasheet.

Current regulation works when the load is connected across the two outputs, or one ouput to GND. It does not work when the load is connected to VM.

If the IC4 register is set to limit the current to 4A (ITRIP_LVL = 00), this could cause what you are seeing.

0 Rick Duncan over 6 years ago in reply to Rick Duncan

TI__Guru** 114905 points

Hi Alen,

Do you have any updates (the scope captures and register settings requested)?

0 Rick Duncan over 5 years ago in reply to Rick Duncan

TI__Guru** 114905 points

Hi Alen,

We have not heard from you in some time and are assuming the issue has been resolved. If it has not, please reply to this thread. If locked, please select "+ Ask a related question".

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DRV8873HEVM: Issue