PC817 SMD Optocoupler SOP-4

PC817 SMD Optocoupler SOP-4 is a highly reliable and widely utilized component that provides essential galvanic isolation between two electrical circuits, preventing high-voltage surges or noise from transferring from one side to the other. This device integrates an infrared light-emitting diode (LED) optically coupled to a silicon NPN phototransistor, encapsulated within a space-saving SOP-4 surface-mount package. The PC817 enables low-voltage digital circuits, like microcontrollers, to safely drive or sense signals from high-voltage, noisy, or ground-isolated systems, effectively breaking ground loops and protecting sensitive electronics. Therefore, designers frequently select the PC817 SMD version for compact and high-density PCB layouts found in modern switching power supplies and industrial control boards.

Key Features:

• High Isolation Voltage: Provides excellent insulation characteristics, typically offering a minimum isolation voltage of 5000 V_RMS, which safeguards connected control systems.
• Compact SOP-4 Package: The Surface-Mount Device (SMD) packaging minimizes board footprint, making it perfect for high-density electronic products and automated assembly.
• Standard CTR Performance: The device features a standard Current Transfer Ratio (CTR) range, ensuring broad compatibility and consistent signal coupling across different operating conditions.
• Fast Switching Speed: Offers sufficient switching characteristics for many common DC-to-DC conversion and digital interfacing applications.
• High Voltage Protection: Effectively isolates low-voltage logic from mains electricity or high-power switching circuits.

Technical Specifications:

• Output Type: Phototransistor (NPN)
• Number of Channels: 1
• Isolation Voltage (V_ISO): 5000 V_RMS (minimum)
• Collector-Emitter Voltage (V_CEO): 35 V (Maximum)
• Collector Current (I_C): 50 mA (Maximum)
• Input LED Forward Current (I_F): 50 mA (Maximum)
• Current Transfer Ratio (CTR): 50% to 600% (I_F = 5mA, V_CE = 5V)
• Operating Temperature Range: −30°C to +100°C

Mechanical Specifications:

• Package Type: SOP-4 (Small Outline Package, 4-pin)
• Mounting: Surface-Mount Technology (SMT)
• Dielectric Material: High-quality insulation layer
• Compatibility: Suitable for standard reflow soldering processes.

Dimensions:

• Body Length: ≈ 4.4 mm
• Body Width: ≈ 4.4 mm
• Height: ≈ 2.1 mm
• Pin Pitch: 1.27 mm (Standard for SOP)
• Weight: ≈ 0.05 g (Ultra-lightweight)

Pinout and Wiring:

• Pin 1 (Anode): Connect to the positive voltage of the input/control circuit, usually via a current-limiting resistor (R_limit).
• Pin 2 (Cathode): Connect to the ground/GND of the input/control circuit.
• Pin 3 (Emitter): Connect to the ground/GND of the output/isolated circuit.
• Pin 4 (Collector): Connect to the V_CC of the output/isolated circuit via a pull-up resistor (R_pull-up) to sense the signal.
• Wiring Note: Furthermore, ensure you use completely separate power and ground planes for the input (Pins 1 & 2) and output (Pins 3 & 4) sides to maintain isolation integrity.

Datasheet Reference:

• Download PC817 Series Optocoupler Datasheet

Commonly Used in:

• Switch Mode Power Supplies (SMPS): Essential for providing feedback and regulation isolation in AC/DC and DC/DC converters.
• Microcontroller Input Interfaces: Safely isolates GPIO pins when monitoring or detecting status from high-voltage machines or peripherals.
• Industrial Control: Used in Programmable Logic Controllers (PLCs) and motor drivers to ensure reliable signal transmission.

Applications:

• Digital Signal Isolation: Transmitting digital ON/OFF signals between circuits with different ground potentials.
• Feedback Loops: Providing isolated voltage or current feedback to a controller in power supply circuits.
• Noise Reduction: Eliminating electrical noise and transients that originate in the power stage from affecting the control stage.
• Level Shifting: Bridging communication between circuits operating at different voltage levels, consequently, simplifying interface design.

Equivalent Models:

• EL817 (Everlight): A functionally identical, widely available optocoupler, often used as a direct replacement for the Sharp PC817.
• LTV-817 (Lite-On): Offers the same pin configuration and electrical specifications in the SOP package.
• TLP181 (Toshiba): Another high-speed, general-purpose phototransistor optocoupler that is often electrically interchangeable.

Package Includes:

• 1 x PC817 SMD Optocoupler SOP-4