Pin 1 (RXD): The pin is an open-drain output and
requires an external pull-up resistor in the range of 1 k? to 10 k? to function
properly. Note that the minimum value depends on the logic supply used. See
IOL in electrical specifications. 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.
Pin 2 (EN): 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 between 1 k? and 10 k?. 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 (NC): Not Connected.
Pin 4 (TXD): The TXD pin is used to transmit the input
signal from the microcontroller. To prevent an over-voltage on this pin, a
series resistor can be placed to limit the input current to the device. A
capacitor to ground can be placed close to the input pin of the device to 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): This pin
connects to the LIN bus. For responder mode applications a 220 pF capacitor to
ground is implemented. For commander mode 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 decoupling capacitor should be placed as close to the device as
possible.
Pin 8 (NC): Not Connected.
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.