LTC4310 question

Question

Dear Support, 
 Would it be possible to place two LTC4310 devices on same bus, such that MCU connect to both isolators and access remote sensors on both ends? 
 Will appreciate your comments,

jnaso · Accepted Answer

Hi mhanuel, 
 The LTC4310 work as a pair. There are two, and only two LTC4310 devices on a transformer. The link between LTC4310 devices cannot be shared by additional devices. 
 There can be two(or more) parallel sets, with the local LTC4310 devices talking to the same master. 
 There is also an LTC4331. The LTC4331 may be interesting for this application depending on how remote these sensors are. The LTC4331 pair can be implemented with isolation, and the local LTC4331 can share the master side bus with other local side LTC4331 devices and/or other I2C slaves. 
 
 Regards, 
 Jason

jnaso · Answer

Hi Manuel, 
 I think two pairs of LTC4331 would be well suited for this application. The transformer/caps for galvanic isolation is optional for the link. It's a 4x5mm package and needs only the external termination resistors. Sure, on the slave side its a bit bigger than the LTC4307 in 3x3 and the pull-ups, but its going to be easy to get the application going with the '4331. I highly recommend giving the '4331 a try. 
 The I2C signal isn't meant to be sent off board on wires. But there a lots of designs that really stretch what I2C can do. The bus buffers are going to help by segmenting the capacitance on the master side and the slave side. Slowing the data rate and the slew rate over the wires to the slaves are going to help. You can disable the LTC4312 buses when you are communicating with local slaves to keep the data rates faster. 
 There are some details on cascading bus buffers in the LTC4312 datasheet. 
 Regards, 
 Jason

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