el817c – dc input phototransistor output optocoupler – everlight electronics

EL817C – DC Input Phototransistor Output Optocoupler – Everlight Electronics

Key features:

  • Single-channel phototransistor output optocoupler
  • High isolation voltage: 5000Vrms
  • Current transfer ratio (CTR) for C grade: 200% to 400%
  • Operating temperature range: -55℃ to +110℃
  • DC input with NPN phototransistor output
  • DIP-4 through-hole package (SMD variants available)
  • Fast response time: 4µs turn-on, 3µs turn-off
  • Compact small outline package
  • Halogen-free and RoHS compliant
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The EL817C is a phototransistor output optocoupler manufactured by Everlight Electronics, a leading Taiwanese optoelectronics company. The device consists of a gallium arsenide (GaAs) infrared emitting diode optically coupled to a silicon NPN phototransistor, all encapsulated in a compact 4-pin DIP package .

This optocoupler provides complete electrical isolation between input and output circuits through an optical transmission path, achieving an isolation voltage rating of 5000Vrms . This makes it ideal for applications requiring safety isolation, noise suppression, and signal transmission between circuits with different ground potentials.

The “C” suffix denotes the Current Transfer Ratio (CTR) grade. For the EL817C variant:

  • CTR range: 200% to 400% at IF = 5mA, VCE = 5V

  • Minimum CTR: 50% (industry standard compliance)

Pin Configuration (DIP-4) :

  • Pin 1: Anode (LED positive)

  • Pin 2: Cathode (LED negative)

  • Pin 3: Emitter (phototransistor)

  • Pin 4: Collector (phototransistor)

Parameters

Parameters Specifications
Manufacturer Everlight Electronics
Part Number EL817C
Number of Channels 1
Input Type DC
Output Type Phototransistor (NPN)
Forward Voltage (VF) 1.2V typical
Forward Current (IF) Max 60mA
Peak Forward Current 1A (1µs pulse)
Reverse Voltage (VR) Max 6V
Collector-Emitter Voltage (VCEO) 35V
Emitter-Collector Voltage (VECO) 6V
Output Current (IC) Max 50mA
Collector Power Dissipation 150mW
Total Power Dissipation 200mW
Isolation Voltage (VISO) 5000Vrms
Current Transfer Ratio (CTR) Range 200% – 400%
Rise Time (tr) Typical 6µs – 18µs
Fall Time (tf) Typical 6µs – 18µs
Turn-On Time 4µs typical
Turn-Off Time 3µs typical
Collector-Emitter Saturation Voltage 0.1V typical
Cut-off Frequency 80kHz typical
Isolation Resistance 5×10¹⁰Ω
Operating Temperature -55℃ to +110℃
Storage Temperature -55℃ to +125℃
Package Type DIP-4
RoHS Compliant Yes

Applications

    • Programmable logic controllers (PLCs) – Input/output signal isolation

    • Switching power supplies (SMPS) – Feedback loop isolation between primary and secondary sides

    • Microcontroller I/O isolation – Protecting MCU pins from high voltage transients

    • Industrial control systems – Ground loop elimination and noise suppression

    • Home appliances – Fan heaters, washing machines, air conditioners, refrigerators

    • Signal transmission – Between circuits with different potentials and impedances

    • Telecommunication equipment – Isolated interfaces

    • Measuring instruments – Isolated measurement circuits

    • Relay and solenoid drivers – Isolating control logic from high-power loads

    Note: The EL817C is an active, in-production device from Everlight Electronics. The naming convention follows: EL = Everlight, 817 = device series, C = CTR grade (200–400%). For surface-mount applications, variants with S (SMD) suffix are available . For applications requiring different CTR values, grades A (80–160%), B (130–260%), or D (300–600%) are available within the EL817 family.

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