There are two or three low voltage levels monitored on the VSUP pin depending on the device chosen. For devices with VCC1 = 3.3V a supply detection threshold, VSUP_PU, a 3.3V level UVSUP_33, and a 5V level UVSUP_5 are monitored. If VCC1 = 5V only the supply detection and UVSUP_5 are monitored. The supply detection level is the boundary between the device in the unpowered or off state and the devices init mode – if the supply voltage rises above the supply detection threshold the device can start init mode and if this falls below the device can be in an off or unpowered state. For devices with VCC1 = 3.3V once the supply voltage has crossed the UVSUP_33 level VCC1 is able to be produce a regulated output and when VSUP has crossed the UVSUP_5 level VCC2 can produce a regulated output and be in regulation while other functions can be utilized. If devices with VCC1 = 3.3V have the supply voltage fall below the UVSUP_5 level the CAN transceiver can turn off, VCC2 can be in pass through, the LIN transceiver, on applicable devices, can still work but does not meet electrical and timing characteristics described in data sheet. For devices with VCC1 = 5V the SBC can react the same way as devices with VCC1 = 3.3V, but instead of the UVSUP_5 level only instead of a combination of UVSUP_33 and UVSUP_5.