We cannot use 2.2kohm REFDI resistor. The REFDI resistor has an operating range of 5.2kohm to 36kohm. We do not guarantee the device functionality when REFDI is beyond the normal operating range. With minimum REFDI resistor of 5.2kohm, the maximum input current limit is 3.39mA (typ) per channel. If we need up to 8mA current limit, will need to parallel several channels to support large cureent. In this case, will need 3 channels and each channel has 2.67mA current limit. The current-setting resistor RREFDI can be calculated using this equation: