Description
4N33 Optocoupler DIP-6 – High CTR Phototransistor Opto-Isolator IC with Base Pin
The 4N33 optocoupler is a high current-transfer-ratio (CTR) opto-isolator designed for applications requiring enhanced sensitivity and reliable electrical isolation. It uses an infrared LED optically coupled to a phototransistor and includes a base pin for improved switching performance. Encased in a DIP-6 through-hole package, the 4N33 is widely used in SMPS feedback circuits, industrial control systems, relay isolation, and signal conditioning where higher CTR compared to standard optocouplers is needed.
| Specification | Details |
|---|---|
| Part Number | 4N33 |
| Device Type | Optocoupler / Opto-Isolator |
| Output Type | Phototransistor with Base Pin |
| Isolation Voltage | Up to 5000Vrms (Typical) |
| CTR (Current Transfer Ratio) | 100% – 300% (Typical) |
| Collector-Emitter Voltage | 30V |
| Input LED Forward Current | 5–10mA Typical |
| Package Type | DIP-6 Through-Hole |
Applications
- SMPS feedback and regulation circuits
- High-sensitivity signal isolation
- Industrial automation and PLC interfaces
- Relay drive and switching isolation
- Noise and ground-loop protection
How to Use
- Connect a current-limiting resistor in series with the input LED.
- Drive the LED using a low-level control or logic signal.
- Use a pull-up resistor on the phototransistor output.
- Utilize the base pin to improve switching speed or sensitivity.
- Maintain recommended isolation distances on the PCB layout.
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