Pin 1(RXD): The RXD pin is an open-drain output and requires and external pull-up resistor in the range of 1 kΩ and 10 kΩ to function properly. If the controller paired with the transceiver does not have an integrated pull-up, an external resistor should be placed between RXD and the supply voltage for the controller.
Pin 2 (EN): EN is an input pin that is used to place the device in low-power sleep mode. If this feature is not used the pin should be connected to the supply voltage for the controller through a series resistor using a pull-up value between 1 kΩ and 10 kΩ. Additionally, a series resistor may be placed on the pin to limit current on the digital lines in the case of an over voltage fault.
Pin 3 (WAKE): SW1 is oriented in a low-side configuration which is used to implement a local WAKE event. The series resistor R5 is needed for protection against over current conditions as it limits the current into the WAKE pin when the ECU has lost its ground connection. The pull-up resistor R4 is required to provide sufficient current during stimulation of a WAKE event. In this layout example R4 is set to 3 kΩ and R5 is set to 33 kΩ.
Pin 4 (TXD): The TXD pin is the transmit input signal to the device from the controller. A series resistor can be placed to limit the input current to the device in the case of an over-voltage on this pin. A capacitor to ground can be placed close to the input pin of the device to help filter noise.
Pin 5 (GND): This is the ground connection for the device. This pin should be tied to the ground plane through a short trace with the use of two vias to limit total return inductance.
Pin 6 (LIN): The LIN pin connects to the TLIN2021-Q1 to the LIN bus. For responder applications a 220 pF capacitor to ground is implemented. For commander applications an additional series resistor and blocking diode should be placed between the LIN pin and the VSUP pin, see Figure 10-1.
Pin 7 (VSUP): This is the supply pin for the device. A 100-nF capacitor should be placed close to the VSUP supply pin for local power supply decoupling.
Pin 8 (INH):The INH pin is used for system power-management. A 100 kΩ load can be added to the INH output to ensure a fast transition time from the driven high state to the low state and to also force the pin low when left floating.
Note:
All ground and power connections should be made as short as possible and use at least two vias to minimize the total loop inductance.