Photodiode

2021年1月2日 - 0 Comments

Photodiode

Photodiode pinout

What is Photodiode? Photodiodes, as the name suggest, are just another type of diodes having an anode and cathode similar to normal LEDs. But, unlike LEDs they do not emit light. Instead, when they detect light they allow some current to flow through it, and the amount of current that flows through the Photodiode is directly proportional to the amount of light detected by the Photodiode. It makes it suitable to use along with the IR LEDs inIR sensor modules。

Photodiode PinOut配置

No:	Pin Name	Identification	Description
1	一个node	领导的时间越长	This is the positive (+) pin of the IR diode. But inversely connected to ground during usage
2	Cathode	The shorter lead	This is the negative (ground) pin of the IR diode. But inversely connected to supply voltage during usage

Photodiode Specifications

波长灵敏度（λp）：940nm
Open Circuit Voltage: 0.39V
Reverse breakdown voltage: 32V
Reverse Light current: 40μA
Reverse Dark current: 5nA
Rise Time/ Fall Time: 45/45nS
View Angle: 80 deg
包装：5mm

Note: Read the article further and check thephotodiode datasheetattached at the end of the article to learn why these parameters are important.

一个lternatives light detectors

ir接收器（TSOP), Phototransistor,LDR，光电器，太阳能电池板

Where to use photodiodes

When photodiodes detect light they allow some current to flow through it and the amount of current is directly proportional to the amount of the light detected by the Photodiode. Due to this property of Photodiode, it is fairly used in situations where light has to be detected. It is also commonly used with IR transmitter (IR LED) to form an IR pair and used in applications like object detection, counter, encoder and much more. So if you are looking for a pair to use with your IR LED or just trying to detect light for your project then this photodiode might be the right choice for you.

How to use a Photodiode

到那个时刻using a Photodiode, one important thing to remember is thatPhotodiode should always be connected in reverse polarity。那就是阳极将连接到地面，阴极将连接到供应电压。当以这种方式连接时（如下所示），光电二极管将根据感应的光开始传导一些电流。在全光条件下可能流动的最大电流为40μa。即使将光电二极管放置在黑暗环境中，它也会消耗等于5NA的电流。

Normally a photodiode will be used as a potential divider here I have used a 10K resistor to form the divider as shown below

光电二极管电路工作

When the light falls on the Photodiode as said earlier a current will flow through it. This current will create a voltage drop across the photodiode and also across the 10K resistor since they form a voltage divider. Then this output voltage can be used to predict the light by reading the voltage through a microcontroller or by using Op-Amps in comparator mode. There are also many other circuits in which you can use a photodiode. This was explained for its simplicity so go ahead and try your own fun circuits