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BQ76952: Disabling and enabling short circuit protection during runtime

Neetika Verma
Prodigy 40 points
Part Number: BQ76952

Tool/software:

Hi TI team,

We have custom requirement where we want to disable and enable short circuit protection during runtime.

By default our settings are enabled as follows:
(Shunt res- 0.1mohm
SCD threshold- 200 A)

BQ76952_SetRegister(DSGFETProtectionsA, 0x80, 1);
BQ76952_SetRegister(DSGFETProtectionsC, 0x40, 1);
BQ76952_SetRegister(EnabledProtectionsA, 0x80, 1);
BQ76952_SetRegister(EnabledProtectionsC, 0x40, 1);
BQ76952_SetRegister(SCDThreshold, 0x01, 1);
BQ76952_SetRegister(SCDDelay, 1, 1);

We want to disable short circuit after first short circuit is encountered. 

and there we are keeping following settings:

BQ76952_SetRegister(DSGFETProtectionsA, 0x00, 1);
BQ76952_SetRegister(DSGFETProtectionsC, 0x00, 1);
BQ76952_SetRegister(EnabledProtectionsA, 0x00, 1);
BQ76952_SetRegister(EnabledProtectionsC, 0x00, 1);

These settings are successfully disabling the protection without entering CONFIG_UPDATE mode.
Now in our application we want to enable the settings again after 10 sec in runtime. At this time current might also be flowing through MOSFETs.

There we observed the settings are not reverted back. 

We also tried to reenable the setting by entering and exiting into CONFIG_UPDATE mode. But in this case, DDSG pin is going low which is disabling my DFET.

Now our requirement is to not to turn OFF DFET/DDSG pin and enable the settings again, which we are unable to handle. Can you help us out with that 
  • 0
    TI__Genius 17845 points

    Hello Neetika,

    We do not recommend changing settings to be changed outside of CONFIG_UPDATE mode. Something to note as well is when you enter CONFIG_UPDATE mode, the FETs are turned off which might explain why the DDSG pin is low. 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 40 points

    DDSG pin will be low if its linked to FET, right? Can we delink this with some setting?

    Is there any way/case where we can enter into CONFIG_UPDATE mode and DDSG is also high? What settings can we keep to achieve this?

  • 0 in reply to Neetika Verma
    TI__Genius 17845 points

    Hello Neetika,

    It is a safety feature of the device to keep the FETs OFF when entering CONFIG_UPDATE mode as the protections aren’t running then.

    Unfortunately, to change the functionality of the DDSG pin, you would need to enter CONFIG_UPDATE mode which would automatically turn OFF the FETs as well. 

    Best Regards,
    Alexis