10.3.4 Undervoltage Lockout and Unpowered Device

The V_CC supply terminal has under voltage detection which will place the device in protected mode if the supply drops below the UVLO threshold. This protects the bus during an under voltage event on V_CC by placing the bus into a high impedance biased to ground state and the RXD terminal into a tri-stated (high impedance) state. During undervoltage the device does not pass any signals from the bus. If the device is in normal mode and V_CC supply is lost the device will transition to a protected mode.

The device is designed to be an "ideal passive" or “no load” to the CAN bus if the device is unpowered. The bus terminals (CANH, CANL) have low leakage currents when the device is unpowered, so the device does not load the bus. This is critical if some nodes of the network are unpowered while the rest of the of network remains operational. Logic pins also have low leakage currents when the device is unpowered, so the device does not load other circuits which may remain powered.