BQ76905: Query for BQ76905 parameters configuration

Harry Ma

Intellectual 1910 points

Part Number: BQ76905

Tool/software:

we design win BQ76905. And there are some technical questions from customer. can you help to support that?

（1）the following picture is customer internal test item and criterion for 4cells system. They wanna confirm what can be programed at the factory and what can’t be programed and is constant? The following criterion is for 4cells system of MP products, BQ79605 is used for 3cells new project.

（2）customer’s pack is 3S cells. Need BQ76905’s over discharge protection voltage point sets as 100mv, and charge protection voltage point sets as 20mv. if BQ79605 can be programed

1 month ago

0 Maxwell Verboncoeur 1 month ago

TI__Mastermind 18360 points

Hi Harry,

Harry Ma said:
the following picture is customer internal test item and criterion for 4cells system. They wanna confirm what can be programed at the factory and what can’t be programed and is constant? The following criterion is for 4cells system of MP products, BQ79605 is used for 3cells new project.

The protections settings can be re-programed by an MCU. These settings do not persist between device resets and would need to be re-programmed again in the event of a reset. The list of programmable settings is available in the device's TRM: https://www.ti.com/lit/ug/sluuci8/sluuci8.pdf

Harry Ma said:
customer’s pack is 3S cells. Need BQ76905’s over discharge protection voltage point sets as 100mv, and charge protection voltage point sets as 20mv. if BQ79605 can be programed

The OV protection is programmable from 0 to 5.5V in 1mV steps. The UV protection is programmable from 0 to 5.5V is 1mV steps as well.

Regards,

Max Verboncoeur

0 Harry Ma 1 month ago in reply to Maxwell Verboncoeur

TI__Intellectual 1910 points

Hi Maxwell

Thanks for your answer.

1. All protections can be-programed in the OTP memory in factory as customer's requirement?

2. How customer assesses the accuracy of protection configuration, what's the error between protection point actually and configured point

0 Maxwell Verboncoeur 1 month ago in reply to Harry Ma

TI__Mastermind 18360 points

Hi Harry,

Harry Ma said:
All protections can be-programed in the OTP memory in factory as customer's requirement?

It can be, although it would require a significant business case.

Harry Ma said:
How customer assesses the accuracy of protection configuration, what's the error between protection point actually and configured point

The cell voltage protection accuracy is the same as the ADC measurement accuracy. The current protection accuracies are listed separately. You can find all of the specs in Section 6 of the datasheet.

Regards,

Max Verboncoeur

0 Harry Ma 14 days ago in reply to Maxwell Verboncoeur

TI__Intellectual 1910 points

Hi Maxwell

customer uses the free sample to build some prototype, and found there is not CHG and DSG driver signal. The schematic is shown as following picture. there are 3cells in system, we added a 9.6V input to simulate the battery.

if the default mode of BQ76905 is sleep mode? how convert the work mode from sleep mode to normal mode if there is no MCU in system?

and if there is way that I can program the OTP memory on customer side to fix the parameter of BQ76905?