For the bidirectional clamping configuration (higher voltage to lower voltage or lower voltage to higher voltage), the EN input must be connected to V_REF2 and both pins pulled to high-side V_DPU through a pullup resistor (typically 200 kΩ). This allows V_REF2 to regulate the EN input. A 100-pF filter capacitor connected to V_REF2 is recommended. The I²C bus controller output can be push-pull or open-drain (pullup resistors may be required) and the I²C bus device output can be open-drain (pullup resistors are required to pull the SCL2 and SDA2 outputs to V_DPU). However, if either output is push-pull, data must be unidirectional or the outputs must be 3-state capable and be controlled by some direction-control mechanism to prevent high-to-low contentions in either direction. If both outputs are open-drain, no direction control is needed.