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Can you clarify the functionality of the Vref pin on the AMIS 42770 Dual high speed CAN transceiver.
Thank you.
Niall Marriott
V ref pin on AMIS 4277x0
is the same function as VREF pin (pin 5) on AMIS30660.
AMIS427x0 is based on CAN IP used in AMIS30660.
Vref is a voltage reference output pin (CAN supply divided by 2)
VREF pin was at the beginning of CAN used with particular NXP CAN controller as a voltage reference used to compare the bus voltage of a remaining single bus line in the event of an accident. If the voltages were the same , it was a recessive bit, if different it was a dominant bit.
It could be eventually used for any other purpose where reference voltage of half a supply is found as handy but in most applications today VREF pin is just left floating. (CAN controllers today are usually integrated in micros and thus for pure CAN interface the pin have no added value).
Often people are mixing up vref pin used like described above with VSPLIT pin (Also VCC/2 reference) for common mode stabilization.
But unlike VREF pin, the Vsplit pin is high voltage, has current limitation and is really serving as to be connected to the middle of CAN termination to improve EME. Vsplit pin is present on AMIS42665, NCV7340, 41, 42, ...
Answered by: ON Semiconductor
2015-01-28 10:06:39.195