BQ78350-R2-DEVICE-FW: short circuit protection ASCD and the latch function.

rens van bolderik

Part Number: BQ78350-R2-DEVICE-FW

Hello I have a question regarding the BQ78350_R1 with the software R2 downloaded in the chip.

When I apply a short circuit and I have:
Setup the protection ASCD with a latch limit to 5, Counter DEC Delay to 3,Recovery to 1, Reset to 5.
PRotection configuation bit DIS_AFEtime_RECOV is set.

Setup the settings Enabled Protections A ASCDL to 1 and ASCD to 0.
The systems keep on repeating after the inetervals to start over again for ever.

Setup the settings Enabled Protections A ASCDL to 1 and ASCD to 1.
The systems switch of when ther is a short and will not turn on automaticly, only when short is removed and charger is applied.

I have tried a lot of combenations and settings and the system keep on reseting or get stuck and can not start the system again when the charger is aplyed again after removing the short.

What I'm looking for a setting that when the system is seeing a short the DSG fet will be turned off. after a second it should start over again and when the short is still there again the DSG FET should be switched off. This should be repeatred upto the latch limit in my case 5 times then it should stop trying forever until the short is removed and a charger is aplied and BMS should be switching on the DSG FET.
I whant to use this for havy load with a high inrush current.

over 4 years ago

0 rens van bolderik over 4 years ago

Intellectual 396 points

BMS_testfiles_4S4P_date 20may2021.zip

0 Matt Sunna over 4 years ago in reply to rens van bolderik

TI__Guru* 81034 points

Hi Rens,

ASCD cannot be disabled because it is a hardware based protection, so you will see the DSG FET disable when a short occurs even if the ASCD bit is set to zero. For the ASCD Reset, I think you should set this to the maximum time so that the latch does not reset after only 5 seconds - can you try setting this to 255 to see the behavior? Are you setting the [LPEN] bit to zero in the Protection Configuration register?

For debug, it would be good if you can send me the .gg.csv file (click on Export in the Data Memory screen). This is much easier to review than the srec file. It would also be good to see a scope capture of the behavior.

Best regards,

Matt

0 rens van bolderik over 4 years ago in reply to Matt Sunna

Intellectual 396 points

chortcircuit test.gg.zip

Hell osorry for the slow response,

I uploaded the CSV file in zip format.

I understand that the ASCD is hardware based. I have LPEN set to one so I was expecting by seting a ASCD count value that it will allow 5 cycles of short circuit and then stay in permanent open FET's.

I have tried the dealy time 255 for counter delay for reset but behavior stay the same

Kind regards
Rens

0 Matt Sunna over 4 years ago in reply to rens van bolderik

TI__Guru* 81034 points

Hi Rens,

It looks like the ASCD and ASCDL bits are both set to zero in your file?

Matt

0 rens van bolderik over 4 years ago in reply to Matt Sunna

Intellectual 396 points

Hello Matt,

When I set ASCD to one then only one short is posible and the dishargport stay off.

When I set only ASCDL then the discharge fet is turned active again after time of the recovery that was set in the software register. and keep continuesly repeating even after the latch limit count in my case set to five is reached.

What I want is that it will repeat activating the the discharge latch for five times and the stops enabeling the dicharge fet until the short is removed and a charger is connected.

Kind regards
Rens

0 Matt Sunna over 4 years ago in reply to rens van bolderik

TI__Guru* 81034 points

Hi Rens,

I notice you also have AOLDL enabled with a latch limit of 0 and a Reset of 15s. Do you think you might be seeing it try to recover? Can you try to disable AOLD and AOLDL to see if it changes the behavior?

Regards,

Matt

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BQ78350-R2-DEVICE-FW: short circuit protection ASCD and the latch function.