SLLU312A July 2019 – May 2022 TCAN4550-Q1
The TCAN4550-Q1 has three undervoltage events that it monitors, UVSUP, UVIO and UVCCOUT. When the supply voltage to VSUP drops below UVSUP threshold the internal regulators may or may not provide the correct voltage levels. The VCCOUT LDO also provides 5 V for the CAN transceiver may enter UVCCOUT at this time. The device then disables the CAN transceiver and start putting the internal logic into a safe state. If VSUP drops more, it eventually reaches the power on reset level. The device comes back up as if it was the first time up once VSUP rises above the UVSUP threshold. When VIO drops below the UVIO threshold the device enters a UVIO protected state. The digital I/O and the Crystal/CLKIN need VIO to perform properly at the correct levels. These undervoltage levels help keep incorrect information off of the bus and vice versa. These help mitigate faults shown as 1, 2, 4, 5, 6 and 9. The undervoltages are covered by safety mechanism SM-02, SM-03 and SM-04.
VSUP | VIO | VCCOUT | DEVICE STATE | BUS | RXD_INT |
---|---|---|---|---|---|
> UVSUP | > UVVIO | > UVCCOUT | Normal | Per TXD_INT | Mirrors Bus |
> UVSUP | > UVVIO | < UVCCOUT | Protected | High Impedance | High (Recessive) |
< UVSUP | > UVVIO | NA | Protected | High Impedance | High (Recessive) |
> UVSUP | < UVVIO | > UVCCOUT | Protected | Recessive | High Impedance |
< UVSUP | < UVVIO | NA | Protected | High Impedance | High Impedance |