The **PC935** (often referred to as the PC925/PC935 series) is a high-speed, high-performance **Photocoupler (Optoisolator)** specifically designed for driving Power MOS-FETs and IGBTs. It is manufactured by Sharp and is known for its ability to provide electrical isolation while maintaining high-speed signal switching. --- ### ## Technical Specifications The PC935 features an integrated circuit on the output side to handle high currents and provide high-speed logic responses. | Parameter | Description | | :--- | :--- | | **Input Type** | Gallium Arsenide (GaAs) Infrared LED | | **Output Type** | Integrated Photodetector + Power Stage (OPIC) | | **Max. Supply Voltage ($V_{CC}$)** | 35V | | **Output Peak Current** | ±0.5A (Source/Sink) | | **Response Time ($t_{PLH}/t_{PHL}$)** | 0.5 µs (Max) | | **Isolation Voltage ($V_{iso}$)** | 5.0 kV (rms) | | **Package Style** | 8-pin DIP / SMT | --- ### ### Internal Architecture The PC935 is not just a simple transistor output optocoupler. It consists of: 1. **Primary Side:** An LED that converts the electrical input signal into light. 2. **Secondary Side:** * A **Photodiode** to receive light. * An **Amplifier Circuit** to boost the signal. * A **Totem-Pole Output Stage** (Push-Pull) which allows it to directly charge and discharge the gate capacitance of a MOSFET or IGBT. --- ### ## Key Applications Because of its high-speed switching and power output capabilities, it is primarily used in power electronics: * **Inverter Circuits:** Used in motor drives to isolate the low-voltage control logic from the high-voltage power stage. * **Switch Mode Power Supplies (SMPS):** Providing feedback or driving power switches. * **Programmable Logic Controllers (PLCs):** Isolating I/O modules from industrial noise. * **Induction Heating:** High-frequency switching control. --- ### ## Pin Configuration (Standard 8-Pin DIP) ```text 1. NC (No Connection) 8. Vcc (Supply Voltage) 2. Anode (LED) 7. Vo (Output) 3. Cathode (LED) 6. Vo (Output) 4. NC (No Connection) 5. GND (Ground) ``` *(Note: Pins 6 and 7 are usually connected together internally or on the PCB for the output signal).* --- ### ## Design Considerations When using the PC935 in a circuit, keep the following in mind: 1. **Bypass Capacitor:** A 0.1µF ceramic capacitor must be placed as close as possible to the $V_{CC}$ and GND pins (Pin 8 and 5) to stabilize the high-speed switching output. 2. **Input Current:** Ensure the input forward current ($I_F$) is within the recommended range (typically 7mA to 16mA) to guarantee fast switching. 3. **Heat Dissipation:** If switching at very high frequencies, calculate the power dissipation of the output IC to avoid thermal shutdown.