BQ76940: LOW side Switching

Hi Manish,
Low side switching is simple and easily implemented as shown in the data sheet. If you have a 2 terminal battery it is the simplest since the system does not know if the high side or low side was switched, the voltage just goes away. Also the battery can reasonably easily handle large voltages with proper component selection.
A complication occurs when you want to communicate with the battery and bring out a communication interface. Most electronics is referenced to the negative potential of the circuit: GND or VSS or in the battery PACK-. If PACK- is switched the communication path no longer works and could cause damage to the components and allow continued charge or discharge of the cells through leakage in the communication path. Some systems may allow a ground reference to be brought out of the battery for the communication path, but if the user were able to connect between PACK+ and the the interface signals or ground an un-protected current path would exist. Most ground-referenced interfaces have a few 10ths of V tolerance to noise which can accomodate sense resistor drops. Other interfaces may provide isolation of 7, 15 or 22V of through their transceivers, but this would be inadequate for a 48V which might be supported by the '940.
High side switching avoids some of these issues depending on the interface. Current out of the battery is limited by the interface driver current, for an interface such as I2C or SMBus the pull ups can be be put in the host and there is no discharge out the communication lines. A ground referenced communicaiton path can continue to operate during battery fault. If the charger can be mistakenly connected to the interface signals, some proteciton may be needed to prevent damage to the components. If needed, reverse voltage tolerance may be more complex with high side switching. High side switching is fairly easy to implement with P-channel FETs although challenges include a fast turn off of the discharge FET and limited options for FETs. N-channel FETs allow more options but need a driver circuit. The bq76200 provides high side FET drive in a battery configuration.
Isolation of the communication lines can also prevent leakage through the communication path. Optical solutions or intergrated parts such as the ISO1541 might be used for I2C or SMBus isolation. For other interfaces, select an appropriate isolator. Isolation will allow communication with the battery during fault if power is available external to the battery.
Either isolation circuits or high side switching add power and cost to the circuit. Consider your system requirements and select an appropriate solution.