If using separate I/O inputs, J2 is used to configure pin 8 to: pullup to VIO supply input, pullup to VCC, pulldown to GND, or VREF or SPLIT termination output. This pin can be pulled up to VIO by connecting a shunt to the J1A2 and J1A1 pins on J2, pulled up to VCC by connecting a shunt to the J1A2 and J1C pins, pulled down to GND by connecting a shunt to the J1A2 and J1A3 pins on J1, or SPLIT termination output by connecting a shunt to the J1A2 and J1B pins.
- VREF or SPLIT termination (VCM): If the device and application support split termination, set J1 to VCM (V common mode) to drive the VREF or SPLIT pin common mode stabilizing voltage output to the center tap of the split termination capacitor.
- No Connection (NC): If the device and application require no use of pin 5, leave open. If the device has the VREF or SPLIT pin, but the application is not using the pin for split termination, then add a capacitor on C1 to improve EMC performance.
- 2nd Mode or Control Input (LBK, EN, AB, SHDN): If the device and application use pin 5 as a second mode or control pin, then set J1 as either a pullup to VCC or pulldown to GND, as necessary. R4 is left open for customers who want to install a resistance to ground.
- I/O and RXD level-shifting supply: If the device and application used with VIO or VRXD to level shift I/O pins on the transceiver, then set J1 to VIO connecting pin 5 of the device to the VIO supply input. Install local buffering and bypass capacitor C10 (no socket) or C18 (has socket).
- Open Drain Output (FAULT): If the device and application use pin 5 as an open drain output, then external pullup is required. Set J1 as either a pullup to VCC or VIO.