TLP785(D4-GRL,F

The TLP785(D4-GRL,F is a high-isolation optocoupler from Toshiba that pairs a gallium arsenide (GaAs) infrared emitting diode with a silicon NPN phototransistor in a compact 4-pin DIP package. The D4 option provides VDE approval per EN 60747-5-2 for reinforced insulation, making it suitable for safety-critical applications. The GRL rank specifies a current transfer ratio of 100-200% at 5 mA forward current, providing a well-defined gain for circuit design. With 5000 Vrms isolation and approvals from UL, VDE, and cUL, this device is ideal for signal isolation in power supplies and industrial equipment.

The TLP785 operates by converting an electrical input signal to infrared light via the GaAs LED, then back to an electrical signal via the silicon phototransistor, with optical coupling providing galvanic isolation between input and output. When forward current flows through the LED, it emits infrared radiation that is detected by the phototransistor base region, generating base current that drives collector current proportional to the LED current. The ratio of output collector current to input LED current is the current transfer ratio (CTR). The GRL rank guarantees 100-200% CTR at 5 mA. The 5000 Vrms isolation barrier is maintained by the internal optical path and package insulation, with minimum creepage of 7.0 mm and clearance of 7.0 mm.

• Switching power supply error feedback loops
• Isolated communication interfaces (RS-485, CAN)
• Industrial PLC digital I/O isolation
• AC zero-crossing detection circuits
• Medical equipment patient isolation barriers