TJA1021 has by default on power on, that the transmitter is off.
It needs the SLP_N line asserted for >Tgotonorm . The transmitter will not work only with bus traffic until it is woken up by signal SLP_N. So there is a scenario where the transmitter reboots due to brownout and our processor does not, leaving the transmitter offline.
TJA1027, TJA1029 appear drop in replacements do not have this feature. They work when they power on, and don’t require this initialization according to the state diagram. So this appears it will solve my problem.
The TJA1029 is specified differently than the TJA1021 mostly with respect to the operating voltage. Operating voltage is up to 18V on The TJA1029 (absolute max = 42) but on TJA1021 both operating and maximum is specified up to 40VDC. We have spent a lot of qualification time using TJA1021 and found this problem.
1) Is there anybody could answer if TJA1021 and TJA1029 is the same or similar IC design with just different state diagram and specifications?
2) Looking to select which is best TJA1027 vs TJA1029, I also cannot tell by the specification any difference between TJA1027 and TJA1029.
|When there is bus traffic an interrupt is passed on the Rx line which wakes up the processor the processor can then set the transceiver enable high to receive the message.|