Analog DevicesEVAL-CN0312-SDPZDevelopment Kits and Tools

EVAL-CN0312-SDPZ is Dual-Channel Colorimeter with Programmable Gain Transimpedance Amplifiers and Synchronous Detectors Board.

The AD8618 quad op amp forms three simple current sources to drive the LEDs with a constant current. The EVAL-SDP-CB1Z generates a 5 kHz clock that modulates one LED by using the ADG633 single pole, double throw (SPDT) switch to turn its current source’s reference voltage on and off. Setting the current sources for the other two LEDs to 0 V keeps them off while not in use.