The VC pins are the input channels for cell voltage measurements from the Main ADC measured in the Cell1 to Cell16 slots of the round robin. The round robin timing is always the same even if fewer than 16 cells are connected to the device (Figure 9-4). That is, for the inactive (or unused) VC channel, the device ignores the respective cell slot, but it does not remove the slot from the round robin cycle. This keeps a consistent measurement timing regardless of the cell number configuration. It also provides a consistent sampling time to the post-ADC digital LPF input.

To determine the number of active VCELL channels for ADC measurement, the ACTIVE_CELL[NUM_CELL3:0] parameter sets the highest active channel number. The device assumes any VC channel below the setting is also active. For example, when a 14S is connected to the device, the MCU sets the [NUM_CELL3:0] to 14S, the Main ADC ignores channel 15 and channel 16 measurements and takes measurements on channels 1 through 14.

The measurement results are reported in the corresponding VCELL*_HI (high-byte) and VCELL*_LO (low-byte) registers, where * = 1 to 16. If the digital LPFs are disabled, the result registers are reported with the single ADC conversion values; otherwise, the result registers are reported with filtered measurement values. For an inactive VC channel, the respective _HI and _LO registers remain with the default value 0x8000.

Figure 9-4 Same Round Robin Timing for 6S Through 16S