Using MC33772 BMS IC for current sensing only (without cell voltage monitoring)

[Ketan_Singla]

Hello,

I would like to use the MC33772 BMS IC only for current sensing (coulomb counting) and not for cell voltage monitoring.

Is it possible to operate the IC without connecting cell voltage inputs?
Is there a minimum number of cells that must be connected for proper operation?

If unused cell inputs are mandatory, how should they be handled?

Thanks in advance.

[JozefKozon]

Hello Ketan,

yes, it is possible to use MC33772C for current measurement only, without need to connect the battery cells. We actually have several reference designs for this case. These are called Battery Junction Boxes. Please check the Hardware section in the MC33772C product page. 

You can check their schematics for connection. E.g. this link: https://www.nxp.com/design/design-center/development-boards-and-designs/RDBESS772BJBEVB

I have also attached the schematic.

In there are used MC33772CTC1AE, MC33772C 1channel version. 

With Best Regards,

Jozef

[Ketan_Singla]

Hi Jozef,

Thanks for your previous response — it was very helpful.

I have a follow-up question for clarification:
If the device is not powered (i.e., VPWR is not present), but current is applied externally to the AFE pins, will any current flow through the device? If so, could this condition potentially cause damage to the AFE?

I’d appreciate any details on expected behavior or recommended precautions for this scenario.

Thanks and best Regards
Ketan

[JozefKozon]

Hi Ketan,

please refer to the Table 7. in the MC33772C datasheet. As long as you don't exceed the values there, the MC33772C will not be damaged. Please pay attention to the GPIOx pins, I2C pins and SPI pins. Their maximum values are derived from VCOM and VDDIO voltages. If the VCOM and VDDIO voltages will be 0V, than their maximum safe voltages are only 0.5V. 

With Best Regards,

Jozef