topic Re: SC33771C coulomb counting in High Performance Analog Front End Interfaces

SC33771C coulomb counting

Ali22 — Wed, 24 Sep 2025 14:39:43 GMT

Dears

I want to know if the coulomb
counting of SC33771C can continue to count during sleep mode?

Re: SC33771C coulomb counting

RafaR — Wed, 24 Sep 2025 21:57:59 GMT

Hello Ali22

Good day!

Sorry, unfortunately it doesn't.

In Sleep Mode, the device significantly reduces its power consumption by disabling most internal functions.

By default, the Coulomb counter does not operate in Sleep Mode because the analog front end (AFE) and ADCs are powered down to save energy.

I recommend you configuring the device to enter to Standby instead of full Sleep, if your application allows it.

I hope this information has helped you, please let me know if you need help with anything else.

Have a great day and best of luck.

Re: SC33771C coulomb counting

Ali22 — Thu, 25 Sep 2025 05:56:08 GMT

Dears

Thanks for your feedback.

But I see here that sleep mode is possible, could you please help me confirm again？
Another question, does SC33771C need to be reinitialized after entering sleep and then being awakened by CSB?

We want to be able to continuously obtain sleep time and Coulomb count values while SC33771 is asleep, but will the Coulomb count related registers clear 0 after initialization?

Re: SC33771C coulomb counting

RafaR — Mon, 29 Sep 2025 06:17:34 GMT

Hello Ali22

Good day!

You're right! Sorry, I already did a more extensive search to review the information for this configuration. I apologize because my first answer was wrong.

Now answering your questions:

does SC33771C need to be reinitialized after entering sleep and then being awakened by CSB?

No, full reinitialization is not strictly required, but some aspects may need to be reconfigured depending on your setup:

CSB wake-up works by transitioning the CSB pin from low to high. This triggers the wake-up sequence, but the device may revert to default cluster ID (CID = 0x00) after sleep or reset.

If you previously assigned a custom CID (e.g., 0x01), you may need to reassign it after wake-up if the device no longer responds to it. This behavior has been observed in practice.

Registers like SYS_CFG2 retain their values across sleep cycles, but some threshold or configuration registers may revert to defaults.

will the Coulomb count related registers clear to 0 after initialization?

Yes, they can be cleared during initialization or reset, but they do not automatically reset to zero unless explicitly commanded:

The COULOMB_CNT1/2 and CC_NB_SAMPLES registers retain their values unless:

A reset command is issued via ADC_CFG [CC_RST] = 1.

A power-on reset (POR) or software reset is triggered.

During sleep, coulomb counting continues, and CC_NB_SAMPLES can saturate to 0xFFFF if not read/reset periodically. [mc33771 sl...Community]

Overflow is indicated by the CC_OVR_FLT flag, and if unmasked, it will activate the FAULT pin.

So, if your goal is to track Coulomb count continuously during sleep, make sure store the values before reset or reinitialization.

I found some posts in the community that might be helpful to you:

https://community.nxp.com/t5/Sensors/mc33771-sleep-coulomb-counter-issue/m-p/2175615

https://community.nxp.com/t5/NXP-Designs/MC33771-Initialization-Issue/m-p/966937

https://community.nxp.com/t5/Sensors/Issue-with-Coulomb-count-in-BMS-S32K144-Board/m-p/1382628

https://community.nxp.com/t5/Power-Management/Counting-problem-with-Coulomb-Count-in-BMS-MC33771B/m-p/1533805

I hope this information has helped you, please let me know if you need help with anything else.

Have a great day and best of luck.