• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 258 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

BQ20Z655-R1: charging profile

BQ20Z655-R1: GPOD

Vincenzo Pizzolante
Mastermind 25296 points
Part Number: BQ20Z655-R1
Other Parts Discussed in Thread: BQ34Z653

hi,

I have some moee questions regarding BQ20Z655-R1 and BQ34Z653.

1) Both BQs have a pin called GPOD (pin no 5). BQ34Z653 uses GPOD pin in order to control any heaters integrated in the system by the user. BQ20Z655-R1 uses GPOD pin to enable the pre-charging MOSFET, but ZVCHG pin can also be used for the same reason. The TRM of BQ20Z655-R1 shows that GPOD pin can be left unused for pre-charging (pages 39-40, chapter 2.5.6, “Pre-Charge”).

Also, I have searched on heaters control in TRMs of both BQs. BQ34Z653 data flash includes special configuration bits for heaters control. These bits are left reserved in the data flash of BQ20Z655-R1.

The question is if there is a way to unlock GPOD pin in BQ20Z655-R1 so that we will use it for heaters control. Or, in general, if we can use the GPOD pin somehow other than to control the pre-charge FET.

2) In BQ34Z653 TRM, page 40, chapter 1.10, “Data Flash Configuration”, it is mentioned that:

HEATALL (Bit 7): HEATALL enables activation of the GPOD output under ALL conditions.

0 = GPOD is only activated when the charger is

detected and the temperature conditions permit

it (default).

1 = GPOD is only activated when the temperature

conditions permit it.

Does this mean that, if HEATALL=1, heaters are activated at both charging and discharging modes of operation?

Additionally, when heaters are enabled, charging/discharging stops or continues in parallel with heating?

3) I see that the “Wake function” (BQ34Z653 TRM, page 45) is considered to be a device mode. However, I cannot find any conditions that need to be met in order for the device to enter this kind of mode. Is it actually a device mode (or maybe a copy/paste from one DS to the ohter or things like that)?

Also, during the SLEEP mode of operation, the device can exit the SLEEP mode and enter the NORMAL mode either when current > sleep current or, if the wake function is enabled, a voltage across SRP and SRN is detected. I feel there is not much difference between these two conditions. Is there something I am missing? Are there any details that make these two conditions discrete since in both of them current must be detected on the shunt resistor?

4) When the battery is not removable from the system, I understand that only NORMAL and SLEEP modes can be entered. SHUTDOWN and SHIP modes depend on pack voltage, which is always present at its nominal value, since battery and BMS system are connected together. In case we want to keep the batteries at an “idle-storage” mode while stored on shelves, we can use the SLEEP mode, which is entered by using the right SBS command or automatically. Am I correct?

5) During the SLEEP mode, heaters are enabled? The GPOD pin operates as in NORMAL mode?

Thanks a lot in advance

KR

Vincenzo

  • 0
    TI__Genius 11535 points

    Hi Vincenzo

    1. No, only the BQ34Z653 can support a heater

    2. Yes, both modes of operation as long as it meets the Charger Detected requirement. Charging is stopped when the heater is enabled

    3. Wake is not a device mode. It is just a function to take the gauge out of sleep mode. You aren't missing anything, they are the same. Also note that SMBus can take the device out of sleep mode as well.

    4. You can use SLEEP mode; however, SHIP and SHUTDOWN modes should still work as long as the rest of the system is shut down and using low enough power  that it still meets the Pack Voltage < Charger Present criteria

    5. No, the heater is only on when the charger is connected. If there is a charger connected then it won't be in sleep mode

    Best,

    Jessica

  • 0 in reply to Jessica H.
    TI__Mastermind 25296 points

    hi Jessica,

    may you elaborate point 2?

    From your reply, I understand that heaters are activated only when a charger is connected (detected).

    However, in BQ34Z653 TRM, page 40, chapter 1.10, “Data Flash Configuration”, it reports the following:

    HEATALL (Bit 7): HEATALL enables activation of the GPOD output under ALL conditions.

    So, when HEATALL=1, does the requirement for charger detection remain? Or, at this case, only temperature conditions are checked in order to allow or not activation of heaters? Because only at this latter case, I understand that heaters could be enabled at both charging and discharging modes of operation.

    Otherwise, I understand that only at charging mode of operation, heaters could be enabled since charger detection is required.

    This is not much clear to me, any clarification of this is very welcome :) 

    thanks a lot in advance

    KR

    Vincenzo

  • 0 in reply to Vincenzo Pizzolante
    TI__Genius 11535 points

    Hi Vincenzo,

    I apologize for the confusion, after re-reading through our documentation I do not think it turns on during discharge. However, the DSG FET does not get turned off so discharging could occur after the heater has already been enabled since GPOD is deactivated when the temperature > DF:Heater Temp.

    Based on the snippet below, my understanding is that the charger still has to have been detected at some point. The difference is whether the heater turns on only at the time the charger is detected vs the charger is already detected and there was a sudden drop in temperature.  

    Let me know if that makes more sense. 

    Best,

    Jessica