ZHCSJK5D January 2018 – June 2022 TCAN4550-Q1
Sleep mode is similar to the standby mode except the SPI interface and INH is disabled. As the low power CAN receiver is powered off of VSUP the implementer can turn off VIO. The nWKRQ pin is powered off the VSUP supply internal logic level regulator. This allows the TCAN4550-Q1 to provide an interrupt to the MCU when a wake event takes place without requiring VIO to be up. When the device goes into sleep mode, the power to the registers and memory is removed to conserve power. This requires the device to be re-configured prior to being put into normal mode. As the SPI interface is turned off, the only ways to exit sleep mode is by a wake-up event, RST pin toggle or power cycle. A sleep mode status flag is provided to determine if the device entered sleep mode through normal operation or if a fault caused the mode change. Register 16'h0820 provides the status. If a fault causes the device to enter sleep mode, this flag is set to a one.
Difference between sleep and standby mode
When entering sleep mode, it is possible for the TCAN4550-Q1 to assert an interrupt due to UVCCOUT event as the LDO is powering down. This interrupt should be ignored or can be masked out by using 16'h830 before initiating the go to sleep command.