LTC4015 - Battery Pack Protection

Hello,

We're in the process of replacing our previous 18650 2S1P Li-Ion charger with a new design based around the LTC4015.   It is stated on page 27 of the datasheet subsection 'LTC4015 Charger Algorithmm Overview' that "The 4015 is not a substitute for pack protection".

Our current approach leverages reverse battery protection on each cell using the 'P-Channel MOSFET Design' as outlined in application note AN-171, in conjunction with the Texas Instruments BQ2920 for pack protection.

Does Analog manufacturer a complementary module that provides pack protection?



correction to spelling mistake.
[edited by: Sense Microsystems at 3:26 AM (GMT -4) on 18 Mar 2021]
  • +1
    •  Analog Employees 
    on Mar 18, 2021 11:43 PM

    Hello,

    Good question - we do not. However, I'll describe how the LTC4015 interacts with pack protection in order to assist you in determining whether the BQ2920 is a good fit.

    Upon startup or removal of the battery after charge termination, the LTC4015 will enter a battery detection state. In this state, the LTC4015 will source/sink current in an attempt to determine whether a battery is present on the BAT node. This test lasts about 1 second and runs about every 30 seconds.

    During the source portion, a current equal to about 1mV/Rsense is sourced to the battery node. With a pack-protected battery present (and no additional loading on this node - more complications if system load is tied directly here as opposed to on the VSYS node), this node will be high-impedance and the voltage is free to rise until it is clamped at the programmed charge voltage. This is partially-intended to pull the battery out of pack-protect. Once pack-protect is exited and the battery is exposed to the LTC4015, charging can begin.

    So, if you can determine that this will work with your method of pack protection, then that method should play well with the LTC4015.

    Regards,
    Zack