ZHCSD75D March 2014 – January 2018
The filter network at the input to the coulomb counter is intended to improve differential mode rejection of voltage measured across the sense resistor. These components should be placed as close as possible to the coulomb counter inputs and the routing of the differential traces length-matched in order to best minimize impedance mismatch-induced measurement errors. The single-ended ceramic capacitors should be tied to the battery voltage node (preferably to a large copper pour connected to the SRN side of the sense resistor) in order to further improve common-mode noise rejection. The series resistors between the CC inputs and the sense resistor should be at least 200 Ω in order to mitigate SCR-induced latch-up due to possible ESD events.