TLP521-4GB

The TLP521-4GB from Toshiba is a quad-channel phototransistor optocoupler combining four gallium arsenide infrared LEDs with silicon phototransistors in a 16-pin DIP package. The GB rank guarantees a minimum CTR of 100%, ensuring reliable signal coupling at low LED drive currents. The 2500Vrms isolation voltage provides robust galvanic isolation meeting UL1577 safety requirements. With 55V VCEO and 50mA collector current per channel, it is suited for industrial control and PLC I/O isolation where multiple isolated channels are needed.

Each channel consists of a GaAs infrared LED optically coupled to a silicon NPN phototransistor. When current flows through the LED, it emits infrared light detected by the phototransistor base, generating base current amplified by the transistor hFE. The output collector current is proportional to LED input current, with the ratio defined as CTR. The GB rank guarantees CTR >= 100% at IF = 5mA. The optical coupling provides electrical isolation with no direct electrical connection.

• PLC digital input/output channel isolation
• AC/DC input module signal conditioning
• Solid-state relay gate drive isolation
• Switching power supply feedback loop
• Communication line interface isolation