The correct way to use LTC4311

Hi Adam,

The LTC4311 is only active when it detects a rising edge on a bus line. It needs to see a voltage threshold crossed at a minimum slew rate to trigger the rise time acceleration. The LTC4311 is slew rate limited, so there can be multiple LTC4311 operating in parallel.

The application bus described here is very long. There will be a lot of parasitic capacitance on the bus, so signal characteristics may be substantially different at different locations. The best signalling may be with parallel LTC4311 and pull-ups distributed in the system.

The LTC4311 allows the 400pF capacitance limit to be greatly exceeded and/or use weak pull-ups for power savings. This application will have a good bit of parasitic capacitance from all this cabling and the LTC4311(s) will help drive that load. But sending single-ended signals off-board may leave the design vulnerable to cross talk between the lines and allow noise from other sources to disturb the I2C signalling. The LTC4331 or LT3960 would provide more robust signalling over cables because they use differential signaling.

Regards,

Jason

Hi Adam,

The LTC4311 is only active when it detects a rising edge on a bus line. It needs to see a voltage threshold crossed at a minimum slew rate to trigger the rise time acceleration. The LTC4311 is slew rate limited, so there can be multiple LTC4311 operating in parallel.

The application bus described here is very long. There will be a lot of parasitic capacitance on the bus, so signal characteristics may be substantially different at different locations. The best signalling may be with parallel LTC4311 and pull-ups distributed in the system.

The LTC4311 allows the 400pF capacitance limit to be greatly exceeded and/or use weak pull-ups for power savings. This application will have a good bit of parasitic capacitance from all this cabling and the LTC4311(s) will help drive that load. But sending single-ended signals off-board may leave the design vulnerable to cross talk between the lines and allow noise from other sources to disturb the I2C signalling. The LTC4331 or LT3960 would provide more robust signalling over cables because they use differential signaling.

Regards,

Jason