8 Low-Side Switching Considerations

Communication with a battery over a ground referenced interface such as SMBus is typically connected to PACK-. When low side protection FETs are used, PACK- is disconnected and reference for the communication lines is lost. The communication interface will not likely work and the signals may present an un-protected leakage path for charge or discharge. Common solutions are to isolate the current paths if appropriate, switch the interface as well as the power path, isolate the interface or use high side protection FETs. The appropriate selection may vary with the application, the designer should be aware that the typical circuit or EVM schematic is not a complete product.