For DS2784, the recovery current (IRC) will range from 2.5mA to 10mA depending on VDD and temperature. For large battery packs, this recovery current might not be enough to charge the battery above the undervoltage threshold within a reasonable amount of time. Additional recovery current can be added by placing a series diode and resistor in parallel with the protection FETs as shown below. The diode ensures there is only current flowing into the battery during charging. The equation used to determine the total recovery current with the addition of the resistor-diode circuit is shown below.
Irc(total) = IRC + (Vchg-Vf-Vbatt_min)/R1
where;
- IRC = DS2784 recovery current
- Vchg = charger voltage during recovery charging
- Vf = forward voltage drop across diode
- Vbatt_min = absolute minimum battery voltage