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BQ2000EVM: Configuration Inquiry

Part Number: BQ2000EVM
Other Parts Discussed in Thread: BQ2000

Hi Team,

My Customer is working with BQ2000EVM, he found that red LED permanently ON. When he removed the Li-Ion pack, the red LED still remains permanently ON. Is this correct? Because in datasheet it says that when no battery detected, the red LED should be OFF.

And another one is datasheet states that the system detects the battery chemistry automatically and proceeds with charging. So, could we connect jumpers at J5 (e.g. 1 jumper at 8 for 8 NiMH batteries) and J6 (e.g. 1 jumper at 3 for 3 Li-Ion batteries) simultaneously so that they can connect whichever battery we want to charge?

Regards,

_Renan

  • Hi Renan,

       I will verify status of Charge LED in battery absent on BQ2000EVM and get back to you as soon as possible.

    In a mixed-chemistry design, a common voltage-divider is used as long as the maximum charge voltage of the nickel-based pack is below that of the Li-Ion pack. Otherwise, different scaling is required.

       

  • Hi Kedar,

    Thank you for this inputs.

    That this mean the mixed chemistry design is built into this EVM? Does that divider exist on this EVM? Because when my customer have 1 jumper each on J5 and J6, they see LED flashing which is not a good sign.

    Looking forward to your inputs.

    Regards,

    _Renan

  • Hi Renan,

        The bq2000 detects the battery chemistry by monitoring the battery-voltage profile during the initial stage of the fast charge. If the voltage on the BAT pin rises to the internal VMCV reference, the IC assumes a Li-Ion battery. Otherwise, the bq2000 assumes a NiCd/NiMH chemistry. While in the fast charge state, the LED pin is pulled low (the LED is on).

       I am still looking into the issue regarding the BQ2000EVM and will report results by 11/11.

  • Hi Renan,

        In battery absent the LED will be high impedance. There should not be an issue with BQ2000 EVM. During battery absent, BQ2000 essentially follows the steps shown in the SLEEP mode section on Page 15. of the datasheet. Figure 12. of the datasheet also shows battery insertion, and the battery absent portion of the scope capture will show expected behavior of the LED pin, which is driven LOW when battery is inserted.