ZHCSD75D March 2014 – January 2018
The ESD components included in the reference design that connect across the back-to-back FETs as well as from PACK+ to ground require trace connections that are as wide and short as possible in order to minimize loop inductance in their return path. This ensures impedance is lowest at the AC loop through the series capacitors and makes this route most attractive for ESD transients such that they are conducted away from the vulnerable low voltage, low power fuel gauge and passive components. The series resistors and Zener diodes connected to the serial communications lines should be placed as close as possible to the battery pack connector to keep large ESD currents confined to an area distant from the fuel gauge electronics. Further, all ESD components referred to ground should be single-point connected to the PACK– terminal if possible. This reduces the possibility of ESD coupling into other sensitive nodes well ahead of the PACK– ground return.