Design and implementation of LED driver circuit applied to fluorescent optical fiber temperature sensor

The 0.18 um CMOS process is used to develop a high-precision power-adjustable LED driver circuit for the hardware circuit of a fluorescent fiber-optic temperature sensor. The driver circuit uses the microcontroller system's VDAC conversion output voltage to create a controlled constant-current source, and it is based on the operational amplifier to create the topology of current series negative feedback. The conversion output voltage VDAC is adaptively adjusted to display the fluorescent signal produced by the fluorescent material excited by the LED driver circuit, correctly. The accurate temperature value can be output by the sensor. This circuit has finished the tape out and testing. The findings indicate that the output current may attain a current regulation range of 12 mA under various supply voltage changes, with VDAC varying from 0 to 3.3 V. The output current is barely impacted by temperature, and the change in output current with VDAC at various temperatures is investigated at 4.5 V supply voltage. The circuit shutdown time at 20 Hz frequency is 21.35 us. Good circuit performance makes it suitable for use in fluorescent fiber-optic temperature sensors.