SCDA043 October   2022 MUX36D08 , TMUX6136 , TMUX6208 , TMUX6219 , TMUX6219-Q1 , TMUX6234 , TMUX6236 , TMUX7208 , TMUX7219 , TMUX7219-Q1 , TMUX7234 , TMUX7236 , TMUX7308F , TMUX7309F , TMUX7348F , TMUX7349F , TMUX8108 , TMUX8109 , TMUX8212

 

  1.   Abstract
  2.   Trademarks
  3. 1Differential, Single-Ended, and Common Mode Signals
  4. 2Characteristics of Interest for Selecting a Multiplexer for High Voltage Common Mode Applications
    1. 2.1 Operating Supply Range
    2. 2.2 Crosstalk and Bandwidth
    3. 2.3 Leakage Current
    4. 2.4 Fault Protection
  5. 3Multiplexers in High Voltage Common Mode Applications
    1. 3.1 PLC Multi-Channel Analog I/O Modules
    2. 3.2 CAN Bus Multiplexing Applications with High Voltage Common Mode
    3. 3.3 High Voltage Battery Cell Monitoring
  6. 4Recommended Multiplexers for High Voltage Common Mode Applications

3.3 High Voltage Battery Cell Monitoring

As alluded to earlier, not all high common mode voltages are unintentional. In this battery cell monitoring application, a high common mode voltage is necessary to measure the battery current in systems that can call for up to 36 V in some automotive sectors. The typical setup uses a current sense amplifier that measures the voltage drop across a small, known resistance and the difference can be used to calculate the current loading of the system as shown in Figure 3-7.

Figure 3-7 High Common Mode Voltage Battery Cell Monitoring with Multiplexer

In this instance, one can see that the common mode voltage would be just under 36 V depending on the load current and is intentional to the design to operate with this high common mode voltage present. So, the multiplexer has to have nominal operation with a high common mode voltage for this application to work properly and a high voltage multiplexer would be the choice for this type of use case.