11.1 Layout Guidelines
- Pins 1, 4, 7 and 10 (RXD1/2/3/4): The pins are open drain outputs and require an external pull-up resistor in the range of 1 kΩ and 10 kΩ to function properly. If the microprocessor paired with the transceiver does not have an integrated pull-up, an external resistor should be placed between RXD and the regulated voltage supply for the microprocessor.
- Pins 2, 5, 8 and 11 (EN1/2/3/4): EN is an input pin that is used to place the device in a low power sleep mode. If this feature is not used the pin should be pulled high to the regulated voltage supply of the microprocessor through a series resistor, values between 1 kΩ and 10 kΩ. Additionally, a series resistor may be placed on the pinto limit current on the digital lines in the case of an over voltage fault.
- Pin 13, 18, 23 and 24 (NC): Not Connected
- Pins 3, 6, 9 and 12 (TXD1/2/3/4): The TXD pins are the transmitter input signals to the device from the microprocessor. A series resistor can be placed to limit the input current to the device in the case of an overvoltage on this pin. A capacitor to ground can be placed close to the input pin of the device to filter noise.
- Pin 14, 19 (GND2/1): 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.
- Pins 22, 20, 17 and 15 (LIN1/2/3/4): This pin connects to the LIN bus. For slave applications a 220 pF capacitor to ground is implemented. For maser applications and additional series resistor and blocking diode should be placed between the LIN pin and the VSUP1/2 pin. See .
- Pin 21, 160 (VSUP1/2): This is the supply pin for the device. A 100 nF decoupling capacitor should be placed as close to the device as possible.
All ground and power connections should be made as short as possible and use at least two vias to minimize the total loop inductance.