20.5.8.1 Integrated Signal Conditioning

The SCLx and SDAx pins have an input glitch filter. The I²C bus requires this filter in both the 100 kHz and 400 kHz systems.

When operating on a 400 kHz bus, the I²C bus specification requires a slew rate control of the device pin output. This slew rate control is integrated into the device. If the DISSLW bit (I2CxCON1[9]) is cleared, the slew rate control is active. For other bus speeds, the I²C bus specification does not require slew rate control and the DISSLW bit should be set.

Some system implementations of I²C buses require different input levels for V_ILMAX and V_IHMIN. In a normal I²C system, V_ILMAX is 0.3 V_DD and V_IHMIN is 0.7 V_DD. By contrast, in a SMBus system, V_ILMAX is set at 0.8V while V_IHMIN is set at 2.1V.

The SMBEN bit (I2CxCON1[25:24]) controls the input levels. Setting SMBEN (= 1) changes the input levels to SMBus specifications.