The phase pointer for the triac trigger signal is synchronized with the 50Hz/60Hz AC voltage applied at the SYNC input by the internal PLL. The triac On/Off status information is also derived from this input. ANODE (Pin 3) CATHODE (Pin 4) and PHOTOUT (Pin 5) These three pins constitute the input/outputs of a transconductance and voltage amplifier pair (See Fig. 6) for converting the current from a photo-diode to a voltage stimulus for application at the SENS input. The photo-signal is used in lieu of a touch plate for a touchless dimmer system. The output at PHOTOUT is governed by the following equation: VOUT = VDD/2 + 2IDRf