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[FAQ] What are the Break-Before-Make (BBM) and Make-Before-Break (MBB) features in analog switches / multiplexers and how are they different?

Other Parts Discussed in Thread: TS5A3160

What is the difference between Break-Before-Make and Make-Before-Break?

Break-before-make (BBM) and Make-before-break (MBB) are two similar yet very different safety delay features that many analog switches / multiplexers provide. Both of these features reference the behavior of the connection of the selected outputs as a switching event is triggered.

In devices with the BBM feature, the connection between two multiplexed paths are never electrically connected when the signal path being selected is changed by the input control logic. This ensures isolation between the two multiplexed paths and prevents signal distortion during the transferring of the signal from one channel to another, which would be desirable in most multiplexed applications. Most TI analog switches and multiplexers support break-before-make switching. Narrowing down which devices have BBM switching is easily done by utilizing the features filter in the TI search tool.  

 

On the other hand, the MBB feature ensures that the connection between two multiplexed paths are never electrically disconnected when the signal path being selected is changed by the input control logic. This will prevent there ever being any instances of a high impedance output being present, which may be desirable in instances where a feedback node requires a load to always be present. Devices such as the TS5A3160 support make-before-break switching. Narrowing down which devices have MBB switching is easily done by utilizing the features filter in the TI search tool.  
 
  


A key distinction that may cause confusion is how the transition time relates to the BBM and MBB time. Any BBM or MBB delay is encompassed in the transition time and doesn’t need to be added for calculating total transition time.

What if my device doesn't specify break-before-make or make-before-make?

In older devices, there may not be a specification for either MBB or BBM. Chances are there is a MBB feature, however TI cannot guaranteed this switching behavior unless it is directly stated in the datasheet. In scenarios where BBM switching is desired but is not explicitly stated in the datasheet and a replacement device which has the desired feature can’t be found through the TI.com search tool, it is recommended to produce the same functionality by utilizing the enable pin, if available, by putting the entire device in a high impedance state before switching the logic to transfer the signal from the current path to the next selected path.

You can find more information about timing parameters and Break-Before-Make delay in the TI Precision Labs video - Switches and muxes : What are timing characteristics?