BQ40Z50-R1: Current calibration

Kaihua Guo

Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQSTUDIO

If Calibrate current with -1000mA, use the same E-load and set the same current value, BQstudio shows the current is -1004mA, it can not be calibrated to -1000mA.

Even calibrate other current value(e.g -100mA or -500mA or -2000mA or -3000mA), the deviation value BQStudio shows is still about 4mA.

However, CC Auto config()[OFFSET_TAKEN] or [AUTO_NESTON]=0, If Calibrate current with -1000mA, BQstudio shows the current is -1000mA.

With the same solution, there is no such issue found in PCBA in other project. Could you explain the reason?

In mass production, will there be any defect if either CC Auto config()[OFFSET_TAKEN] or [AUTO_NESTON] is set as 0?

over 7 years ago

0 David Hien over 7 years ago

TI__Genius 10830 points

Hi Kaihua,
Thank you for your interest in our products. A BMS expert has been assigned to your question.

Regards,
David

0 Swaminathan Ramanathan75031 over 7 years ago

TI__Expert 6575 points

Hi Kaihua,
The [OFFSET_TAKEN] bit should always be cleared when programming a new PCB, since the device will do it's own auto calibration when a sleep condition is detected and set the "CC Auto Offset". Also, "CC Auto Offset" should be set to 0 initially.
However, the [AUTO_NESTON] and [AUTO_CAL_EN] should be set so that the auto calibration happens correctly, and the correct offset is used during operation.
Regards,
Swami

0 Kaihua Guo over 7 years ago in reply to Swaminathan Ramanathan75031

Prodigy 40 points

Hi,Swaminathan

Why the current can not be calibrated,when both [AUTO_NESTON] and [OFFSET_TAKEN] = "1",What could be the cause?Thanks.

0 Swaminathan Ramanathan75031 over 7 years ago in reply to Kaihua Guo

TI__Expert 6575 points

Hi Kaihua,
It should be possible to calibrate even when [AUTO_NESTON] is set, and it is recommended that [AUTO_NESTON] is set.
However the [OFFSET_TAKEN] bit should only be set by the fw, and not manually, otherwise the internal calibration can conflict with the external calibration and cause issues.
Regards,
Swami

0 Wu JW over 7 years ago in reply to Swaminathan Ramanathan75031

TI__Intellectual 2935 points

Hi, Swami,

Customer want to know how to avoid the issue? Do you have any suggestion for that?

0 Swaminathan Ramanathan75031 over 7 years ago in reply to Wu JW

TI__Expert 6575 points

To avoid the issue, the following steps should be taken:
1. When configuring a new pack, the [AUTO_NESTON] and [AUTO_CAL_EN] bits must be set and the [OFFSET_TAKEN] bit must be cleared.
2. When he gauge is put in sleep mode, the gauge will internally short SRN and SRP and remove any device offset automatically. This can not be performed externally, and the user can not set the "Auto Offset" value manually, since this will not be correct.
Regards,
Swami

0 Kaihua Guo over 7 years ago in reply to Swaminathan Ramanathan75031

Prodigy 40 points

Hi,Swami

When the [OFFSET_TAKEN] bit can be set？or can never be set？

Power management

Power management forum

BQ40Z50-R1: Current calibration