What is PC817 Optocoupler : Working & Its Applications

An optocoupler is also called an optoisolator, photo-coupler & optical isolator is one kind of semiconductor device that allows the electrical signal to transmit between two isolated circuits through light. This component includes two parts like an LED and a photosensitive device. There are different kinds of optoisolator ICs are available like PC817 IC, MOC3021 IC, MOC363 IC, MCT2E IC & PC817 optocoupler.

What is PC817 Optocoupler?

PC817 IC is an optocoupler that includes a phototransistor and an IR diode. In various circuits, filters play a key role to remove the noise. When the circuit including resistor and capacitor always eliminates the noise from the incoming signal however the resistor & value capacitor frequently depends on the inward signal.

PC817 Optocoupler
PC817 Optocoupler

This circuit is simply appropriate wherever the incoming signal includes some data however when we need to transmit the signal from one element of the circuit to the other element although the signal includes noise, so we have to utilize the blend of IR Tx & Rx.

In the circuit of PC817 optocoupler, the IR gets the noisy signal from one part and transmits it to another using the IR signal so that it performs based on the design of the circuit. PC817 IC includes an LED & a phototransistor which are connected jointly optically. The signal can be transmitted optically in between an i/p and an o/p side without any physical connection.

To any microcontroller or any DC device with less voltage, it can be connected directly. From every face of this IC, the input voltages will have a similar effect; it will simply transmit the signal toward the receiver. After that, the receiver will provide the logic signal like an output. This IC has several uses because of its tiny size & control operation.

PC817 Optocoupler Pin Configuration

The pin configuration of PC817 Optocoupler is shown below, This IC includes 4 pins like 2 input pins and 2 output pins where each pin and its functionality is discussed below.

PC817 IC Pin Diagram
PC817 IC Pin Diagram

Pin1 (Anode): In the optocoupler IC, this is an Anode pin of infrared LED (Tx). This pin provides a logical input signal toward the internal IR.

Pin2 (Cathode): In this IC, this is the cathode pin of the infrared LED (Tx). It will provide the infrared to create the common GND through the circuit & power supply

Pin3 (Collector): This is an o/p pin of the IR Tx in the optocoupler and it provides the logical o/p through getting the infrared signal.

Pin4 (Emitter): This is a GND pin for IR Rx in the IC & it is used to build the common GND through the circuit & power supply.

An alternative PC817 ICs are 6N136 IC, MOC3041 IC, MOC3021 IC, 6N137 IC & 4N25IC. Equivalent PC817 ICs are PC817A, PC817C, PC817B & PC817D.

Features & Specifications

The specifications of the PC817 Optocoupler include the following.

  • Forward Voltage of Input Diode is 1.25V
  • At the collector terminal, the maximum current ratio is 50mA
  • The maximum Voltage of the Collector-Emitter is 80V (max)
  • At the Collector & Emitter Terminals, the ratio of maximum voltage is 80V
  • Maximum Collector Current is 50mA
  • Rise Time is18us
  • Fall Time is 18us
  • The cut-off frequency is 80 kHz
  • The max operating temperature ranges from -30 to 100 degrees.
  • Power Dissipation is 200mW.
  • The internal resistance is 100 ohms.
  • The internal storage temperature of this IC ranges from -55 -125 degrees.
  • While doing soldering, the optocoupler’s temperature range is 260 degrees. Once the temperature increases then the IC will be damaged.

The features of the PC817 IC Optocoupler include the following.

  • This IC includes 4-pins and is available in two packages like SMT and DIP
  • This IC includes internal protection for both input & output from electrical isolation and it protects up to 5KV.
  • This IC is used with an additional resistor through high voltage devices to function through fewer voltage devices.
  • This IC can function through any type of device including internal interfaces such as Microcontrollers, TTL devices & also with HIGH DC voltage through some inside resistors.
  • PC817 Optocoupler comes with inside safety from reverse current, because of the flow of current in one way; this IC defends the infrared from any current.

PC817 IC Optocoupler Circuit

The circuit diagram of the PC817 IC Optocoupler is shown below. In this circuit, an IC like PC817 is an essential component that is used to switch the DC circuit.

A Photo-Transistor is used in the above optocoupler circuit, and this circuit works as a usual Transistor switch. In this circuit, an optocoupler-based low-cost phototransistor is utilized. The controlling of an IR LED can be done through the switch ‘S1’.

PC817 Optocoupler Circuit Diagram
PC817 Optocoupler Circuit Diagram

Once the switch is activated, then the 9V battery provides current toward the LED using the 10K resistor. The intensity of the LED can be controlled through the resistor ‘R1’. If we modify the value of resistance to lesser, then LED intensity will be high making the transistor gain high.

On the other side of the circuit, the photo-transistor can be controlled through the IR LED. Once the LED produces IR light, then the phototransistor will make contact & the output voltage will be ‘0’, so the load will be turned off which is connected beyond it.

It is very essential to remember that according to the PC817 IC datasheet, the transistor’s collector current is 50mA. The ‘R2’ resistor provides the output voltage like 5V and here the resistor used is pull up. In this circuit design, the optocoupler based on phototransistor is used through the microcontroller to detect the pulses otherwise interrupt.

The PC817 optocoupler working is extremely easy however to utilize it through various devices appears with different specifications. On the input side, the optocoupler needs a current limiting resistor but at the output, we need to fix the logic output pin through the power pin. Once the infrared signal is generated, the logic condition will be altered from one to zero because of the change within the current flow.

How to use safely in a Circuit for a Long Time?

When you want to use a PC817 IC Opto-coupler in your circuit very securely, it is suggested always to stay under the complete highest ratings. Load should not drive above 50mA and like a normal LED; the internal infrared LED can be derived by using a current limiting resistor at the pin-1 that means anode or cathode pin of IR LED.

The device should not operate under -30 degrees centigrade & above 100 degrees centigrade. Always you should store above -55 degrees centigrade & under 125 degrees centigrade temperature.


The applications of PC817 Optocoupler include the following.

  • In Isolation Circuits
  • Switching Circuits with Microcontroller I/O
  • Isolation of Signal
  • Circuits of Noise Coupling
  • AC/DC Power control
  • It is Reliable to utilize because of its functionality.
  • For Transmission of Signal
  • Noise Coupling Circuits
  • Uses as Switching because of the noise factor neglect
  • Opto-coupler is used in a home appliance to regulate AC loads by giving the pulse of change within the frequency that provides the capability to manage the AC load at a fixed range.

Thus, this is all about an overview of a PC817 Optocoupler or optoisolator datasheet. This IC has many benefits because of the increasing IoT field. So it is widely using to control different appliances in daily life. This IC helps design electronic circuits where there is a possibility for voltage surge or voltage spikes which may damage the circuit components.

So this IC helps in isolating the circuit. In addition, it is also used to eliminate noise from the signal, segregate DC & circuits with low voltage from AC & circuits with high voltage. This IC is also used to control AC voltage or large voltage with a small analog or digital signal. Here is a question for you, what are the different types of optocouplers available in the market?