The 5-V VCC only devices are supplied by a single 5-V rail. The digital inputs have TTL input thresholds and are therefore 5 V and 3.3 V compatible. The RXD outputs on these devices are driven to the VCC rail for logic high output. Additionally, the TXD pin is internally pulled up to VCC, and the S pin is pulled low to GND. The internal bias of the mode pins may only place the device into a known state if the terminals float, they may not be adequate for system-level biasing during transients or noisy enviroments.
TXD pull up strength and CAN bit timing require special consideration when these devices are used with CAN controllers with an open-drain TXD output. An adequate external pull up resistor must be used to ensure that the CAN controller output of the micrcontroller maintains adequate bit timing to the TXD input.