FAQ: Logic and Voltage Translation > IxC >> What Makes an I2C Buffer Hot-Swappable?
Hot-Swap also known as Hot-Plug means the unpowered device can be inserted into a live backplane without disruption of service on the backplane.
What makes an I2C buffer hot-swappable is that the buffer implements some type of detection circuit that allows the buffer to detect when the I2C is either ending communication, or when the bus has been idle for a period of time on the backplane side.
For example, an I2C daughter card being inserted into a live backplane. When this happens, the card side needs to ensure that the insertion will not disrupt any I2C communication, or get the I2C bus stuck LOW from uncharged capacitance on the card.
See typical application of the TCA9511A:
The SDAIN & SCLIN pins of the TCA9511A face the backplane side.
Before the TCA9511A makes the following connections:
SDAIN --> SDAOUT
SCLIN --> SCLOUT
The buffer looks for either two conditions...
(1) stop condition
(2) bus idle time > 150 us (max)
Once 1 of these conditions is met, the TCA9511A will make the internal connections to connect the "IN" side to the "OUT" side therefore connection the backplane to the daughter card all while the backplane is being powered.
Our portfolio supports one more type of hot-swap buffer named TCA4307. This device is p2p to TCA9511A and electrically the same with the exception of the stuck bus recovery feature.
Please see this [FAQ] What is Stuck Bus Recovery?
For additional information, please see these application notes:
I2C Solutions for Hot Swap Applications
I2C Stuck Bus: Prevention and Workarounds