Sleep mode is the lowest power mode of the device. The CAN driver and main receiver are turned off and bi-directional CAN communication is not possible.
The low power receiver with bus monitor and WAKE circuits are supplied via the VSUP supply terminal. The low power receiver is able to monitor the bus for any activity that validates the wake up pattern (WUP) requirements, and the WAKE monitoring circuit monitors for state changes on the WAKE terminal for a local wake up (LWU) event. The VCC and VIO supplies may be turned off or be controlled via the INH output for additional system level current savings.
The valid wake up sources in sleep mode are:
Additionally, EN and nSTB can be used to change modes if both VCC and VIO are powered.
If a bus wake up pattern (WUP) or local wake up (LWU) event occurs, the internal WAKERQ flag is set and the device transitions to standby mode which in turn sets the INH output high. The wake up source recognition flag (WAKESR) is set either high or low to identify which wake event occurred. This flag can be polled via the nFAULT pin after the device is returned to normal mode and only until there have been four recessive to dominant transitions on the TXD pin.
The wake source (WAKESR) flag has two states:
If both a local wake and a remote wake request occur, the device indicates whichever event was completed first.
The device transitions into sleep mode if at any time either or both the VCC or VIO supplies have an under voltage condition that lasts longer than timer tUV. If VIO remains active in sleep mode, it is recommended to drive the EN pin low once the device has transitioned into sleep mode to reduce the current consumption due to the internal pull-down on the EN terminal.