Infrared emission and reflection sensor.portable radio transceiver

　　With the advancement of science and technology, the degree of automation of various electronic products has also increased, and the higher the degree of automation, the more sensing components are included. In order to avoid human eyes from being interfered by the light emitted by various products or devices in the environment when sensing, infrared products that cannot be detected by human eyes are used as sensors. This application manual will explain how to use infrared emitting components and infrared receiving components for object detection applications.

　　The most common infrared emitting and receiving components are infrared light-emitting diodes and optical triodes. Figure 1 shows the application circuit of basic IR LED with PT.

　　IR LED is the transmitting end, Forward current (Forward current; The larger the emission, the greater the intensity of the radiation.

　　PT is the receiving end, and the greater the irradiance received, the greater the photocurrent IC(on) generated.

　　Adjust the Rlimit value to control the size of the IF.

　　Adjust the RL value to control the size of Vout.

　　Vout can be connected to the MCU ADC(Analog-to-Digital Converter) or GPIO for level determination.

　　Judgment description: No irradiance, PT cut-off, Vout output high level (Vcc)

　　When irradiance is low, PT is on and Vout output is high (Vcc – (Ic x RL))

　　At high irradiance, PT is saturated and Vout output is low (VCE(sat))

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