2 Timer Based Charge

A Timer Based Charge NiMH profile also uses a constant current charge but at a reduced current for a longer time. Termination is controlled by a timer that ends charge after programed time has expires. This allows a lower charge current to be used for the charger, below 1C. See Figure 2-1

The BQ25172 uses this charge profile, timer is set by a pulldown resistor on TMR pin between 4 and 22 hours. As the timer is increased a lower charge current can be used. This allows flexibly to adjust the charger to match available current and battery pack size.