BQ40Z50-R2：BQ40Z50-R2 Communication Issue

Hello,

Can you please go more into depth about when the communication is becoming unavailable and what protection is getting triggered during this time?

Regards,

Anthony Baldino

Hello, Anthony.

When I disconnect the communication, the COV delay time is no longer within the set range (delay set at 2 seconds, activates after 7 seconds). Additionally, it may require a higher voltage to activate (COV set at 4.25V, actually activates at 4.29V).

You can use an EVM board to verify this issue.

Hello, Anthony.

Could you explain how the Sleep voltage time is counted?

I think that when I disconnect the communication, it affects my COV delay time.

Regards,

Wayne

Hi Wayne,

The sleep voltage time is counted using an internal counter within the gauge, to which I do not believe that removing communication would affect the counting. Has it been observed that when communication is available, the delay time for the COV protection is accurate?

Regards,

Anthony Baldino

Runing mode(Continuous communication)

Let it sit for 3 minutes

Sleep mode(Cut off communications)

Hi Wayne,

I see that even while communication is running, it is still greater then the delay. Would it be possible to run this test again while having the bqStudio log on, with a sampling rate of 1s (how to change this can be found on the preferences page below)? This would allow us to see how the gauge is processing this protection when triggered.

Regards,

Anthony Baldino 

Hi Anthony

This is a 1-second sampling rate. Do you have any other questions?

I don't understand why adjusting the sampling rate affects the Coefficient of Variation (COV). Please explain and give examples.

I am asking for the second time, have you verified it using the EVM board? Or do you not have an EVM board to verify?

Please explain the method of calculating time in sleep mode.

Regards,

Wayne

Hi Wayne,

Wayne0831 said:

This is a 1-second sampling rate. Do you have any other questions?

I don't understand why adjusting the sampling rate affects the Coefficient of Variation (COV). Please explain and give examples.

The changing of the sampling rate will not affect the current results, however when the log file is created it will give more resolution of what is going on within the gauge at this time. Since the default timing is 4s, it would be more difficult to truly determine what is going on within the gauge when the protection is triggered. 

Wayne0831 said:

I am asking for the second time, have you verified it using the EVM board? Or do you not have an EVM board to verify?

I will look into verifying this on the EVM.

Wayne0831 said:

Please explain the method of calculating time in sleep mode.

The time in sleep is calculated using a internal firmware counter, that will wake the gauge up to sample voltage every period determined by the value inputted for the Voltage Time parameter. Has it been observed in your test that altering this value changes the amount of delay?

Regards,

Anthony Baldino

Hi Anthony

I reduced the voltage, and the startup time can be shortened (Status: Sleep mode).

Regards,

Hi Wayne,

I am slightly unclear on the message above, are you saying that it has been observed that reducing the voltage allows for the device to enter sleep quicker?

Regards,

Anthony Baldino

I lowered the voltage-time setting and verified the COV after entering sleep mode, which enabled it to start up faster.

Hi Wayne,

I see in the image earlier sent in this thread that the voltage time is also set to 5s, what was the voltage time set here that enabled the faster start up?

Regards,

Anthony Baldino

Changed 5 seconds to 1 second but it's still out of range. 

The actual measured value is 6 seconds.

Hi Wayne,

What is the current reading during this time? If you are trying to exit sleep, the gauge relies on the current reading to break the Sleep Current threshold. The Voltage Time dictates the sampling time between voltage measurements while the gauge is in sleep.

Regards,

Anthony

The sleep voltage time setting is 1 second, and the protection is triggered in 6 seconds.

COV delay time is set to 2 seconds (range is 2~5 seconds), so 6 seconds exceeds the intended range.

When a customer uses the product, there is current consumption, and even without communication, there is enough current to break sleep mode.

Hi Wayne,

For the COV protection, can you please tell me what the Latch Limit and Counter Dec Delay parameters are currently set to?

Regards,

Anthony

Hi Wayne,

After receiving council from our team regarding this issue, firmware protections measure in intervals of one second, which in turn will add roughly another second to the trigger time of the protection. In the situation above where the gauge is starting in sleep, the device is required to wake up from sleep and enter normal mode at this time, then sample for the protection, hence why there is more time added to the delay.

More information regarding this can be found in the FAQ below:

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1111094/faq-what-are-the-differences-between-the-hardware-and-firmware-protections

Regards,

Anthony

The COV delay time is set to 2 seconds, so the specification is between 2 and 5 seconds, accounting for other effects.

Hi Wayne,

Yes, to where I believe that if you are triggering the protection in sleep mode there can be more delay since it has to exit sleep mode as well.

Regards,

Anthony