BQ28Z610: Questions about ZVCHG and security key

Jayden Li

Expert 3225 points

Part Number: BQ28Z610

Hi team,

Two questions need your detailed support.

I have tried to find the detail description for ZVCHG (Zero-volt Charging) in our datasheet and TRM, however, there is no detail explanation in our datasheet and TRM. I know if voltage above this threshold, ZVCHG Mode would exit.However, I don’t know what is ZVCHG Mode really mean and what is the relationship between ZVCHG Mode and precharging, could you please help explain ZVCHG operation principle and the relationship between ZVCHG Mode and precharging? Any training material is appreciated. Thanks.

In the Chapter 9.5 of BQ28Z610TRM, a guide for changing security keys is given as below. What does the 2^nd key here mean? The second command starting at 0x60 or Byte1? If it is the second command starting at 0x60, how can I finish it within 4s? Customer found it is hard

And I found a picture in .

It looks like it did not follow the 4s limit between the first command and second command, which confused me and my customer a lot.

over 4 years ago

0 Nick Brylski over 4 years ago

TI__Mastermind 19195 points

Hi Jayden,

Zerovoltage charging is when battery is deeply discharged, the threshold where ZVCHG mode goes to pre charge mode can be configured. Looking into your second question.

Best regards,

0 Nick Brylski over 4 years ago in reply to Nick Brylski

TI__Mastermind 19195 points

Hi Jayden,

The 2nd key refers to the full access key.

Best regards,

0 Jayden Li over 4 years ago in reply to Nick Brylski

TI__Expert 3225 points

Hi Nick,

Thank you for your support!

While our customer changed the key with same command, the key was not changed successfully.

If the second command is followed within 3s, the key was changed successfully.

If the second command is followed more than 3s, even within 4s, the key changed failed.

Two questions confused us:

1. If the 2nd key refers to the full access key, why the process shown in first picture failed?

2. If the 2nd key refers to the the second command starting at 0x60, why even the interval between the two commands si within 4s, the process still failed, which did not align with TRM.

Sincerely,

Jayden

0 Nick Brylski over 4 years ago in reply to Jayden Li

TI__Mastermind 19195 points

Hi,

To confirm, customer is seeing that key must be changed with 3 seconds?

Best regards,

0 Kang Kang over 4 years ago in reply to Jayden Li

TI__Mastermind 24870 points

1. You will need to wait at least 4 seconds between unseal and seal.

0 Jayden Li over 4 years ago in reply to Nick Brylski

TI__Expert 3225 points

Hi, Nick

As shown in the pictures I posted before.

Customer is seeing the second command starting at 0x60 must follow the first command starting at 0x3E within 3s, or the security change process would failed. Which don't align with datasheet.

And I found another post in our E2E forum, as shown in the following link. The interval between second command starting at 0x60 and the first command starting at 0x3E is beyond 4s, but he changed the security successfully.

So,

1.We want to the real meaning of this: For this activity, the 2nd key must be sent within 4 s of sending the first key; otherwise, the request will not be accepted.

2.Why the customer have the 3s limitation, is it normal operation?