For cell connections, it is important to remember that high current flows through the top and bottom connections; therefore, the voltage sense leads at these points must be made with a Kelvin connection to avoid any errors due to a drop in the high-current copper trace. The location marked 4P in Figure 9-4 indicates the Kelvin connection of the most positive battery node. The connection marked 1N is equally important. The VC5 pin (a ground reference for cell voltage measurement), which is in the older generation devices, is not in the BQ40Z50-R2 device. Therefore, the single-point connection at 1N to the low-current ground is needed to avoid an unwanted voltage drop through long traces while the gas gauge is measuring the bottom cell voltage.

Figure 9-4 Li-Ion Cell Connections