EL111X-G Series Phototransistor Photocoupler Datasheet - 5-Pin SOP Package - 8mm Creepage - Isolation 5000Vrms - English Technical Document

1. Product Overview

The EL111X-G series represents a family of phototransistor-based photocouplers (optocouplers) designed for applications requiring robust electrical isolation and signal transmission between circuits of different potentials. The core function of this device is to transfer an electrical signal using light, providing galvanic isolation between the input (infrared emitting diode) and output (phototransistor detector) sides. This isolation is critical for protecting sensitive circuitry from high voltages, noise, and ground loops.

The series is characterized by its compact 5-pin Small Outline Package (SOP) with a low profile of 2.0 mm, making it suitable for space-constrained PCB designs. A key distinguishing feature is its 8mm long creepage distance, which enhances reliability and safety in high-voltage environments by increasing the surface distance between conductive parts along the package body. The devices are constructed using compound materials free from halogens (Bromine <900 ppm, Chlorine <900 ppm, Br+Cl <1500 ppm) and antimony trioxide (Sb2O3), aligning with environmental and safety regulations.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Input Forward Current (IF): 60 mA (Continuous). The peak forward current for a 1µs pulse is significantly higher at 1.5 A, allowing for brief overcurrent conditions during switching.
• Input Reverse Voltage (VR): 6 V. Exceeding this voltage in reverse bias can damage the input LED.
• Output Collector-Emitter Voltage (VCEO): 80 V. This is the maximum voltage that can be applied across the output transistor when the base is open.
• Output Collector Current (IC): 50 mA.
• Total Power Dissipation (PTOT): 250 mW. This is the combined maximum power dissipation for both input and output sides.
• Isolation Voltage (VISO): 5000 V_rms for 1 minute at 40-60% relative humidity. This is a critical safety parameter, tested with input pins (1,2) shorted together and output pins (3,4,5) shorted together.
• Operating Temperature (TOPR): -55°C to +110°C.
• Soldering Temperature (TSOL): 260°C for 10 seconds, compliant with typical reflow soldering profiles.

2.2 Electro-Optical Characteristics

These parameters define the device's performance under normal operating conditions (Ta=25°C unless noted).

2.2.1 Input Characteristics (Infrared LED)

• Forward Voltage (VF): Maximum 1.5 V at IF = 50 mA. A typical value would be lower, around 1.1-1.3V.
• Reverse Current (IR): Maximum 10 µA at VR = 6 V.
• Input Capacitance (C_in): Typical 50 pF at 1 kHz. This affects high-frequency switching performance.

2.2.2 Output Characteristics (Phototransistor)

• Collector-Emitter Dark Current (I_CEO): Maximum 100 nA at V_CE = 20V, I_F = 0mA. This is the leakage current when the LED is off.
• Collector-Emitter Breakdown Voltage (BV_CEO): Minimum 80 V at I_C = 0.1mA.
• Collector-Emitter Saturation Voltage (V_CE(sat)): Maximum 0.4 V at I_F = 10mA, I_C = 1mA. A low saturation voltage is desirable for output stages driving logic-level inputs.

2.2.3 Transfer Characteristics

These parameters describe the coupling efficiency and speed between input and output.

• Current Transfer Ratio (CTR): This is the ratio of output collector current (I_C) to input forward current (I_F), expressed as a percentage. The EL111X-G series is offered in multiple CTR grades (ranks), each with a specified min/max range at defined test conditions. This allows designers to select a device with consistent gain for their application.
  • EL1110, EL1116, EL1117, EL1118, EL1119: Tested at I_F = 5mA, V_CE = 5V. Ranges vary from 50-600% (EL1110) to 200-400% (EL1119).
  • EL1112, EL1113, EL1114: Tested at I_F = 10mA, V_CE = 5V. Ranges are 63-125%, 100-200%, and 160-320% respectively. These parts also have specified minimum CTR values at I_F = 1mA.
• Isolation Resistance (R_IO): Minimum 5 x 10¹⁰ Ω at 500V DC. This indicates the extremely high DC resistance between the isolated sides.
• Floating Capacitance (C_IO): Maximum 1.0 pF at 1 MHz. This low capacitance helps maintain high common-mode transient immunity (CMTI) by minimizing capacitive coupling of noise.
• Switching Times: Measured with V_CE = 5V, I_C = 5mA, R_L = 100Ω.
  • Turn-on Time (t_on): Typical 4 µs.
  • Turn-off Time (t_off): Typical 3 µs.
  • Rise Time (t_r): Typical 2 µs, Maximum 18 µs.
  • Fall Time (t_f): Typical 3 µs, Maximum 18 µs.
  These times define the device's ability to follow digital signals. The maximum limits ensure functionality across the full temperature and production range.

3. Grading System Explanation

The primary grading system for the EL111X-G series is based on the Current Transfer Ratio (CTR). Different part numbers (denoted by the 'X' in EL111X) correspond to specific, guaranteed ranges of CTR measured under standard conditions (I_F=5mA or 10mA, V_CE=5V). This allows designers to:

1. Ensure Circuit Stability: Selecting a tighter CTR range (e.g., EL1117: 80-160%) provides more predictable output current for a given input current, reducing the need for wide-tolerance biasing circuits.
2. Optimize Power Consumption: For a required output current, a higher CTR device (e.g., EL1119) can be driven with a lower input LED current, saving power on the primary side.
3. Match Design Requirements: Different applications may require different gain. Logic interface circuits might use a standard CTR device, while analog signal transmission might benefit from a higher, more linear CTR part.

The ordering information clearly defines this grading with the 'X' character (0, 2, 3, 4, 6, 7, 8, 9).

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet ("Typical Electro-Optical Characteristics Curves"), their typical behavior can be described based on phototransistor photocoupler principles:

• CTR vs. Forward Current (I_F): CTR is not constant. It typically peaks at a moderate forward current (often around 5-10mA for these devices) and may decrease at very low or very high currents due to LED efficiency and transistor saturation effects.
• CTR vs. Temperature: CTR generally has a negative temperature coefficient; it decreases as the junction temperature increases. Designers must account for this derating over the operating temperature range.
• Output Current (I_C) vs. Collector-Emitter Voltage (V_CE): The phototransistor behaves like a current source for a fixed LED current until it enters saturation. The saturation region is characterized by a low V_CE(sat) as specified.
• Switching Time vs. Load Resistance (R_L): Switching times (t_r, t_f) are highly dependent on the load resistor and any parasitic capacitance. A smaller R_L generally provides faster fall times but reduces output swing and increases power dissipation.

5. Mechanical and Package Information

The device uses a 5-pin SOP (Small Outline Package) with a height of 2.0 mm. The pin configuration is standardized:

1. Anode (Input LED+)
2. Cathode (Input LED-)
3. Emitter (Phototransistor)
4. Collector (Phototransistor)
5. Base (Phototransistor, typically left open or connected for speed-up techniques)

The package includes a recommended pad layout for surface mount assembly, which is crucial for achieving reliable solder joints and proper mechanical stability during reflow. The 8mm long creepage distance is a physical design feature of the package mold that increases the surface distance between the input and output pins, directly contributing to the high 5000Vrms isolation rating and compliance with safety standards.

6. Soldering and Assembly Guidelines

The device is rated for a maximum soldering temperature of 260°C for 10 seconds. This aligns with standard lead-free reflow soldering profiles (IPC/JEDEC J-STD-020). Key considerations include:

• Use the recommended PCB land pattern to prevent tombstoning or misalignment.
• Avoid excessive solder paste which could cause bridging between the closely spaced pins or short the creepage gap.
• Follow standard moisture sensitivity level (MSL) handling procedures for plastic packages, typically involving baking if the device has been exposed to ambient humidity beyond its rated floor life.
• Storage temperature range is -55°C to +125°C.

7. Packaging and Ordering Information

The product is available in multiple packaging options to suit different production scales:

• Tube: 100 units per tube (Standard or with VDE option).
• Tape and Reel: 3000 units per reel. Two reel options (TA, TB) are available, likely differing in tape width or component orientation. Both can be combined with the VDE safety approval option.

The part number structure is: EL111X(Y)-VG

• EL111: Base part number.
• X: CTR Rank (0,2,3,4,6,7,8,9).
• Y: Tape & Reel option (TA, TB, or blank for tube).
• V: Optional VDE safety approval marking.
• G: Denotes Halogen-free construction.

Device marking on the package includes a code for year and week of manufacture, along with the device number and optional VDE indicator.

8. Application Recommendations

8.1 Typical Application Scenarios

• Programmable Logic Controller (PLC) I/O Modules: Isolating digital signals from field sensors/actuators from the central processing unit.
• Switching Power Supplies: Providing feedback isolation in flyback or other isolated converter topologies.
• Industrial Communication Interfaces: Isolating RS-485, CAN, or other serial bus lines to prevent ground loops and enhance noise immunity.
• Medical Equipment: Isolating patient-connected circuits from mains-powered sections, where safety isolation is paramount.
• Home Appliance Control: Isolating low-voltage microcontroller signals from triac-driven AC motor or heater circuits in appliances like fan heaters.
• Measurement Instruments: Isolating analog signal conditioning stages from data acquisition systems.

8.2 Design Considerations

• Input Current Limiting: Always use a series resistor to limit the LED forward current (I_F) to the desired value, calculated as (Supply Voltage - V_F) / I_F. Do not exceed the absolute maximum ratings.
• CTR Degradation: Be aware that CTR can degrade over the lifetime of the device, especially if operated at high temperatures or high LED currents. Derate the initial CTR value in critical designs.
• Speed vs. Current Trade-off: Higher I_F generally improves switching speed but increases power dissipation and may accelerate CTR degradation. The load resistor R_L also critically affects switching speed and output voltage swing.
• Noise Immunity: The high isolation resistance and low coupling capacitance provide good common-mode rejection. For very noisy environments, ensure a clean layout with proper grounding and consider adding bypass capacitors near the device pins.
• Using the Base Pin (Pin 5): Leaving the base open is standard. Connecting a resistor between base and emitter can reduce the phototransistor's gain but significantly improve its switching speed (especially turn-off time) by providing a path to remove stored charge.

9. Technical Comparison and Advantages

The EL111X-G series differentiates itself in the photocoupler market through several key features:

• Long Creepage SOP Package: The 8mm creepage in a standard SOP footprint offers a superior isolation rating (5000Vrms) compared to many standard SOP photocouplers, often rated for 2500Vrms or 3750Vrms. This provides a safety margin and meets stricter isolation requirements without moving to larger packages.
• Comprehensive Safety Approvals: The series carries approvals from major international safety agencies (UL, cUL, VDE, SEMKO, NEMKO, DEMKO, FIMKO, CQC), simplifying compliance for global products.
• Environmental Compliance: Halogen-free and RoHS-compliant construction addresses environmental regulations and supply chain requirements.
• Wide CTR Selection: The multiple, clearly defined CTR grades offer designers flexibility to optimize for gain, power, or cost.

10. Frequently Asked Questions (Based on Technical Parameters)

1. Q: What is the purpose of the long creepage distance?
   A: Creepage is the shortest distance between two conductive parts along the surface of the insulating package. An 8mm creepage distance significantly increases the breakdown path for surface contamination (dust, moisture), which is essential for achieving and maintaining the high 5000Vrms isolation voltage rating, especially in humid or polluted environments.
2. Q: How do I choose the right CTR grade?
   A: Select based on your circuit's required output current and input drive capability. If your microcontroller GPIO pin can only source 5mA, choose a higher CTR grade (e.g., EL1119) to get sufficient output current. If you need consistent, predictable gain for analog sensing, choose a grade with a tighter range (e.g., EL1117). Always consult the min/max values at your specific operating point.
3. Q: Can I use this for analog signal transmission?
   A: Yes, but with caveats. The phototransistor's response is not perfectly linear, and CTR varies with temperature and current. It is best suited for lower-frequency or digitally-represented analog signals (like PWM). For precision analog isolation, dedicated linear optocouplers or isolation amplifiers are more appropriate.
4. Q: What is the difference between the TA and TB tape & reel options?
   A: The datasheet shows two different tape dimension drawings. The key difference is likely the orientation of the component within the tape pocket ("Direction of feed from reel") and possibly tape width. TB option has a Ko dimension of 2.25mm. Consult the manufacturer or the detailed tape specs for your pick-and-place machine compatibility.
5. Q: How does temperature affect performance?
   A: Temperature primarily affects CTR (decreases with increasing temperature) and the forward voltage V_F of the input LED (also decreases). Switching speeds may also vary. Designs intended for the full -55°C to +110°C range must account for these variations, especially the CTR derating.

11. Practical Design Example

Scenario: Isolating a 3.3V microcontroller GPIO signal to control a 12V relay on the isolated side. The relay coil requires 30mA to activate.

Design Steps:

1. Choose CTR Grade: The required I_C is 30mA. The microcontroller can source ~10mA. Required CTR = (30mA / 10mA) * 100% = 300%. At I_F=10mA, EL1114 has a CTR range of 160-320%. We select EL1114, acknowledging that at the minimum CTR (160%), I_C would be 16mA, which might not be sufficient. We may need to drive the LED harder or choose a different grade/device.
2. Recalculate with EL1119: EL1119 is rated at I_F=5mA. CTR range is 200-400%. If we drive it at I_F=7.5mA (within rating), using the typical CTR, we can expect I_C around 22.5-30mA. This is borderline. A better solution is to use a transistor on the output to drive the relay, using the photocoupler only as a logic-level isolator.
3. Input Resistor Calculation (using EL1114 at I_F=10mA): Assume V_F ~ 1.2V. Microcontroller voltage is 3.3V. R_limit = (3.3V - 1.2V) / 0.01A = 210 Ω. Use a standard 200 Ω resistor.
4. Output Side: Connect the phototransistor collector to the 12V supply via the relay coil. The emitter connects to ground. Place a flyback diode inversely across the relay coil. The phototransistor will saturate when on, with V_CE(sat) < 0.4V, applying nearly the full 12V across the relay.
5. Speed Consideration: The relay is slow, so the photocoupler's ~4µs turn-on time is irrelevant. No base resistor is needed for speed-up.

This example highlights the iterative process of matching device parameters to application requirements.

12. Operating Principle

A photocoupler, or optocoupler, is a device that transfers electrical signals between two isolated circuits using light. In the EL111X-G series:

1. An electrical current is applied to the input pins (1-Anode, 2-Cathode), forward-biasing the internal infrared light-emitting diode (IRED).
2. The IRED emits infrared light proportional to the forward current.
3. This light travels across a transparent insulating gap (typically a molded plastic) and strikes the base region of a silicon phototransistor on the output side.
4. The incident light generates electron-hole pairs in the base, effectively acting as a base current. This causes the phototransistor to conduct between its collector (pin 4) and emitter (pin 3).
5. The resulting output collector current (I_C) is approximately proportional to the input LED current (I_F), with the proportionality constant being the Current Transfer Ratio (CTR).
6. The key is that the only connection between input and output is the light beam; there is no electrical conductive path. This provides the galvanic isolation, blocking high voltages, ground potential differences, and noise.

13. Technology Trends

Photocoupler technology continues to evolve alongside system demands:

• Higher Speed: Demand for faster digital isolation in motor drives, communications, and ADCs drives development of photocouplers with faster switching times (nanosecond range) and higher common-mode transient immunity (CMTI).
• Integration: There is a trend towards integrating additional functionality, such as gate drivers for IGBTs/MOSFETs, error amplifiers for power supplies, or even digital isolators with multiple channels in one package.
• Improved Reliability and Lifetime: Focus on materials and design to reduce long-term CTR degradation, especially for high-temperature automotive and industrial applications.
• Miniaturization: While maintaining or improving isolation ratings, packages continue to shrink (e.g., ultra-miniature SOP, wafer-level packaging) to save board space.
• Alternative Technologies: Photocouplers face competition from other isolation technologies like capacitive isolators (using SiO2 barriers) and magnetic (transformer-based) isolators, which can offer higher speed, lower power, and better integration. However, photocouplers remain dominant in many applications due to their simplicity, high voltage capability, well-understood reliability, and cost-effectiveness for standard-speed requirements.

The EL111X-G series, with its focus on high isolation voltage in a compact, environmentally compliant package, addresses the persistent need for reliable, safety-approved signal isolation in a wide range of industrial and consumer applications.