What is Break Before Make (TBBM)?
This is a bus switch with an SPDT configuration, which specifies that two switches cannot be turned on at the same time when switching.
TBBM is an abbreviation for "Brake Before Make," and it refers to the regulation of the time that two switches must be turned off to prevent both switches from being turned on at the same time.
By setting this regulation, it is possible to prevent two signals from being shorted.
※In general, turning on a switch is called Make and turning it off is called Break.
A brief explanation is given using the data sheet of TC7PCI3212MT (2 differential channel 1-2 multiplexer/demultiplexer). Table-1 shows the TBBM specified in AC characteristics. Minimum (3ns) and maximum (9ns) at supply voltage (VCC = 3.3 V ± 0.3 V) are specified. In other words, when switching between two switches, it is designed so that both switches are always turned off for a period between 3ns and 9ns.
Please refer to Fig. 1 for the method of measuring TBBM.
With the power supply voltage (VCC = 3.3 V), the (Bn+/Bn-) and (Cn+/Cn-) terminals are fixed at 1.2 V, and the SEL terminal is switched between high and low to switch between the two switches. If there is a period during which both switches are turned off at the same time as the switching timing, the An+/An- terminals will go low (VOL). It measures the period during which the two switches are turned off at the same time.
Table-1 TBBM specification of TC7PCI3212MT
This specification is also specified for load switches, etc.
Related Links
The following documents also contain related information.
