TCAN1043A-Q1: TCAN1043A-Q1

Hi Mostafa,

INH should be turned off in SLEEP mode, did you mean that INH was still HIGH after mode changed from go-to-sleep to SLEEP mode?

Please note in go-to-sleep mode the INH output is HIGH, the device has to wait for t > tGOTOSLEEP to enter the SLEEP mode.

Let me know if it's not the case.

Regards,

Sean

Hi Sean,

Thanks for your reply,

Ok let me describe more accurately. Here is the case: we are in Standby mode and we intend to go to Sleep immediately (less than 1 ms). This is how we are doing: 

1- The state is Standby

2- we go to Normal first (by setting EN=High, nSTB=High) to ensure the SWE timer is reset. 

3- "Immediately", we set EN=High, nSTB=Low

We suppose that it should first go to "Go-To-Sleep" mode and after max 50 micro secs it should go to Sleep, where INH pin is Low. However, still we see that it takes more than 3 mins until the mode changes to Sleep (almost equal to t_inactive). Is it really possible to go from Standby to Sleep directly and quickly. If not, what should we do ? 

Regards,

Hi Mostafa,

If CAN communication is occurring while the device is in go-to-Sleep mode, this will trigger a CAN bus wake up and keep the device out of Sleep mode and in Standby mode. Once in Standby mode the device will enter SLEEP mode after SWE timer expired (t > t_inactive). If the device is in Normal Mode, the go-to-sleep mode can not be skipped before entering SLEEP mode. But you can force the device directly chance from Standby mode to SLEEP mode by a UVCC or UVIO event (VCC falls below UVCC or Vio falls below UVIO for t > tUV)

Regards,

Sean

So, you mean it is not needed even to go to normal mode from standby mode first. We only need to make sure we have no wakeup event. It means if we set En to High and nSTB to Low, and if we have wakeup event, it should go to Sleep mode less than 1ms ? 

Mostafa,

You cannot go to SLEEP mode directly from Standby mode within 1ms, because a UVCC or UVIO event is > 100 ms. What I said above is a wakeup event during go-to-sleep can make the mode change to Standby, that might be the reason it couldn't go to SLEEP mode. 

mostafa safi said:

It means if we set En to High and nSTB to Low, and if we have wakeup event, it should go to Sleep mode less than 1m

After you set En to High and nSTB to low, you should make sure there is NO wakeup event, which will wake up the device and go to Standby mode.

Regards,

Sean

Thanks

yes we set En to High and nSTB to Low to go "Go-To-Sleep" and then to Sleep mode, which should take less than 1ms, I suppose. And, we are sure that have no traffic on the bus (we are using NO_COM concept in AUTOSAR Com stack). However, we still cannot go to sleep quickly, Is it that the wakeup event is so sensitive to the noises or something like that. We had the same situation in another project which was using TCAN1043. We should wait at least 5 min so that the ECU can go to sleep (and we cut the power off instead of reset not to wake up again with these guys) because of these Cantrcvs !

Mostafa,

Would you please share the schematic (and waveform capture if possible) so we can make sure WAKE pin is also configured correctly. Because wakeup event can also happen due to LWU by WAKE pin. 

Regards,

Sean

yes. I have the schematic only!

Mostafa,

The WAKE is grounded which is correct. For those bus capacitors C2002 & C2003, ensure placement close to connector and along signal path.  The CMC can be placed between the termination resistors and the transceiver, so that the cable and rest of the CAN bus "see" the termination impedance first. This also allows the CMC to be last line of defense for high frequency noise going into the transceiver, and the first line of defense for emissions out of the transceiver.

Now back to our question, since you don't have waveform, can you double check the voltage of your pins to make sure they have passed the correct thresholds (EN > VIH, nSTB<VIL)?  nSTB pin has to be held low until t_go_to_sleep expires which can be at most 50 us.

Also, would you try disconnect the CAN bus and repeat the test.

Regards,

Sean

Hi Sean 

I have double checked the pin status according to the datasheet and did the test with the can bus disconnected.  Anything else to be considered ?

Best,

Hi Mostafa,

Right now I think your setup is fine and the device should work normally. Can you please provide the waveform of EN, STB and INH? 

Regards,

Sean