TJA1059 can transceiver, can I supply VIO from a micro itself?

[jumpifnotzero]

Specifically about the TJA1059, but also any NXP CAN controller that has a VIO pin that doubles as an UNDERVOLTAGE OFF setting.

The VIO pin the 1059 when unpowered will put the transceiver in an OFF / Bus Disconnected / Undervoltage mode as per 7.3.3 in the datasheet and 3.2.3 in the Application Hints.

The electrical requirements show no more than 600uA used by the VIO pin, which my micro should cover easily. I can't think of any other issues except maybe a sleeping micro not powering VIO properly, but same issues would apply to Standby pins.

If I was to connect VIO directly to an output of the microcontroller - can I use that as switchable ON/OFF? Can I use a push/pull output safely? OR, is it wise to use a transistor? Maybe pull up with open collector? Other options?

https://www.nxp.com/documents/data_sheet/TJA1059.pdf 

https://www.nxp.com/docs/en/supporting-information/AH1401_Application_Hints_TJA1059.pdf 

[guoweisun]

Hi,

For your application,how do you wake up TJA1059 if VIO is low? Do you need this wake up function?

[jumpifnotzero]

Right now my micro is 5V, so I can just tie VCC and VIO together. I think what you are getting at is if I cut VIO, I won’t get any wake functiinality - that would make sense because the transceiver wouldn’t know which voltage to signal at. This is also OK, for what I would be doing, I would not need wale on an unpowered transceiver.

im trying to take advantage of the transceiver feature that can lines are disconnected from an unpowered / off transceiver. What I don’t really get is if a micro output would be appropriate for tying to VIO directly.

[guoweisun]

Hi，

If so you can connect MCU output with VIO as transceiver OFF/others states,please refer to AN1401 page10 Table1.