ZHCSKL0D December 2009 – December 2019 BQ24610 , BQ24617
PRODUCTION DATA.
If the SRP-SRN voltage decreases below 5 mV (the charger is also forced into nonsynchronous mode when the average SRP-SRN voltage is lower than 1.25 mV), the low-side FET is turned off for the remainder of the switching cycle to prevent negative inductor current. During DCM, the low-side FET only turns on for around 80 ns when the bootstrap capacitor voltage drops below 4.2 V to provide refresh charge for the bootstrap capacitor. This is important to prevent negative inductor current from causing a boost effect in which the input voltage increases, as power is transferred from the battery to the input capacitors and leads to an overvoltage stress on the VCC node and potentially causes damage to the system.