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BQ24073EVM: Choose the right product and configure

Hardware Firmware Team Hardware Firmware Team
Prodigy 10 points
Part Number: BQ24073EVM
Other Parts Discussed in Thread: BQ24073, BQ24075, BQ25180, BQ24072

We are currently in phase of designing a new IoT product for measuring accurately Temperature and Humidity and report them in our back end. Our same previous product uses a non rechargeable battery so there is not any need for dedicate IC for recharging and dynamically change path for powering system.

We persuaded your evaluation board of BQ42073 and we are trying to configure it to meet our needs.

Some questions:

1. We want in final product to monitor battery level in order to report/alarm in case of low battery. There is a product of that series that system output follows battery level + some millivolts. What about BQ42073 which provides 4.4V out. At what voltage and above of actually battery level 4.4V remains? Is it ok to put a divider at battery input with a mosfet as a switch and measure battery voltage level at some times?

2. Can you use this IC to charge/recharge one pack of two in parallel 15650. The actual pack includes protected circuit for OverVoltage, UnderVoltage and Temperature levels.

3. What is the minimum current that this IC consumes when it is active and standby mode?

4. We want to configure IC in stand alone configuration.

Thank you in advance

Best Regard

Yannis

  • 0
    TI__Mastermind 23170 points

    Hi Yannis,

    Hardware Firmware Team Hardware Firmware Team said:
    What about BQ42073 which provides 4.4V out. At what voltage and above of actually battery level 4.4V remains? Is it ok to put a divider at battery input with a mosfet as a switch and measure battery voltage level at some times?

    If VIN is above VOUT + VDO, VOUT will always be 4.4V for this device. Yes you can put a voltage divider at the battery input to monitor the battery voltage some times.

    Hardware Firmware Team Hardware Firmware Team said:
    Can you use this IC to charge/recharge one pack of two in parallel 15650.

    You can but the BQ24073 will not handle cell balancing to ensure that both batteries are at the same capacity and voltage

    Hardware Firmware Team Hardware Firmware Team said:
    What is the minimum current that this IC consumes when it is active and standby mode?

    When active, the device consumes about 1.1 mA. In Standby int consumes about 41.3 uA

    Hardware Firmware Team Hardware Firmware Team said:
    We want to configure IC in stand alone configuration.

    Yes, as this is a resistor configurable device, it will be a standalone setup. 

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 10 points

    Hello Anthony and sorry for our late response!

    Just some clarifications:

    1. At what battery voltage level Vout 4.4V drops(start decreasing or cut off)?

    2. About Active/Standby current, our new broduct will basically operate with battery for long time hopfully, so management IC will use the battery as source, this operation is concerned as active, stand by or some else mode at the IC point of view?

    Thank you in advance

    Best Regard

    Ioannis

  • 0 in reply to Hardware Firmware Team Hardware Firmware Team
    TI__Mastermind 23170 points

    Hi Ioannis,

    Hardware Firmware Team Hardware Firmware Team said:
    At what battery voltage level Vout 4.4V drops(start decreasing or cut off)?

    If the battery is the only source of power connected (VIN is not present), then VOUT will be VBAT - VDO(BAT-OUT). I'll need to double check and see if there is a cutoff if only on battery power.

    Hardware Firmware Team Hardware Firmware Team said:
    About Active/Standby current, our new broduct will basically operate with battery for long time hopfully, so management IC will use the battery as source, this operation is concerned as active, stand by or some else mode at the IC point of view?

    The BQ24073 does not have any standby mode enabled if only powered by battery. If you're able to switch to either the BQ24075/6/8/9 device, you can follow this app note (Achieving Ship Mode With the BQ24075, BQ24076, BQ24078, and BQ24079) that implements a low Iq mode known as Ship Mode that will turn off the OUT when on battery power using some external hardware (FET and a couple of resistors).

    Are you able to share when you plan to start mass production?

    Best Regards,

    Anthony Pham

  • 0 in reply to Anthony P Pham
    Prodigy 10 points

    Hi Anthony!

    Let me clarify some concerns about our new device, so you can help us to find a better management IC or configure the one we choose appropriate.

    1. Our new device includes a GSM modem which is very "hungry" on power consumption for some seconds when first time try to connect to network that's theoretically is ok with Lion-Ion batteries, but voltage ranges of GSM modem are between 2.8 to 4.3. Lion Ion batteries full charge voltage is 4.2 which is 100mV lower than GSM modem's maximum voltage. In our best case scenario(without using a dc to dc converter) we want an charger/management IC whose Vout will follow battery voltage level when it will not exceed 4.2V while is in charging mode. Can we configure the IC we choose at that Vout level during charging and discharging modes or we need to choose another IC?

    2. Sorry for repeating same question, while we are in battery mode(discharging) the IC we choose consumes ~1.1mA no matter what is the actual load of the system? Our circuit on sleep mode consumes about ~20uA. We definitely do not want management IC to consumes more than system.

    3. We are in the middle of R&D phase of this new device, we do not know the exact date of mass production but our estimation is on start of July.

    Thank you in advance

    Best Regard

    Yannis

  • 0 in reply to Hardware Firmware Team Hardware Firmware Team
    TI__Mastermind 23170 points

    Hi Yannis,

    Appreciate the clarifications!

    Hardware Firmware Team Hardware Firmware Team said:
    In our best case scenario(without using a dc to dc converter) we want an charger/management IC whose Vout will follow battery voltage level when it will not exceed 4.2V while is in charging mode

    I think I have a possibly idea of how to make the BQ25180 work but it may not be super ideal. I'll need a couple of days to see it works. Would an I2C charger work? The BQ25180 is the next generation version of the BQ24073. It's in a nice little WCSP package and I2C configurable. It'd simplify a lot of stuff when it comes to keeping your output at about battery level (BAT + 225 mV). 

    I know the output would need to cap out at 4.3 V which is where I'll need to try some stuff to see if we can get a software solution to your liking. 

    With the BQ24073, the VOUT is fixed at 4.4 V. You may be better with the BQ24072 which does have a similar battery tracking VOUT but you'd need to force it into DPPM to ensure VOUT stays within range as the battery is charging, which is a bit more difficult to do on a standalone device which is why I'm suggesting the BQ25180.

    Hardware Firmware Team Hardware Firmware Team said:
    while we are in battery mode(discharging) the IC we choose consumes ~1.1mA no matter what is the actual load of the system? Our circuit on sleep mode consumes about ~20uA. We definitely do not want management IC to consumes more than system

    If you're just looking at the battery Iq, you will definitely see something less than 1.1 mA. I'll have to double check and see if it is less than 20 uA with no load. 

    I will note that the BQ25180 has a battery quiescent current in the single digit uA range that satisfy this critieria.

    Best Regards,

    Anthony Pham