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BQ2004H- changing charging rate 'on the fly'

Peter Belleau
Prodigy 120 points
Other Parts Discussed in Thread: BQ2004H

From the datasheet I see that the charging rate for the BQ2004H is set according to pins TM1 and TM2. Can the rate be changed while the chip is running, or does it have to be powered down, the settings changed, then powered up again? Thanks.

  • 0
    TI__Guru**** 150870 points

    Actually, the charge current is set by the resistor Rsns.  The TM pins just adjust the charge timer for different charge rates as set by Rsns.  Page 7 of the datasheet:

    "Maximum charge time is configured using the TM pin. Time settings are available for corresponding charge rates of C/4, C/2, 1C, and 2C. Maximum time-out termination is enforced on the fast-charge phase, then reset, and enforced again on the top-off phase, if selected. There is no time limit on the trickle-charge phase."

    Further on "Charge current is monitored at the SNS input by the voltage drop across a sense resistor, RSNS, between the low side of the battery pack and ground. RSNS is sized to provide the desired fast charge current."