8-Pin SOP High Speed 1Mbit/s Transistor Photocoupler EL045X EL050X Series Datasheet - Package SO-8 - Voltage 5V/15V/30V - English Technical Document

1. Product Overview

The EL045X and EL050X series are high-speed, transistor-output photocouplers (optocouplers) designed for signal isolation in demanding electronic circuits. Each device integrates an infrared light-emitting diode (LED) optically coupled to a high-speed photodetector transistor. A key architectural feature is the separate connection provided for the photodiode bias and the output transistor's collector. This design significantly enhances switching speed by reducing the base-collector capacitance of the input transistor compared to conventional phototransistor couplers. The devices are housed in a compact 8-pin Small Outline Package (SOP) that conforms to the standard SO-8 footprint, making them suitable for space-constrained applications.

The core advantage of this series lies in its combination of high-speed data transmission capability (up to 1 Mbit/s) and robust electrical isolation. They offer a high common-mode transient immunity (CMTI), particularly the EL0453 variant which guarantees a minimum of 15 kV/µs, making them ideal for noisy environments like motor drives and switch-mode power supplies. The series is characterized by a wide operating temperature range, compliance with international safety and environmental standards (UL, cUL, VDE, RoHS, Halogen Free, REACH), and is available in different current transfer ratio (CTR) grades to suit various application needs.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operating the device continuously at or near these limits is not recommended.

• Input (LED Side): Maximum continuous forward current (I_F) is 25 mA. It can handle a peak forward current (I_FP) of 50 mA under pulsed conditions (50% duty cycle, 1ms pulse width). A very high peak transient current (I_Ftrans) of 1A is allowed for very short pulses (≤ 1µs, 300 pps). The maximum reverse voltage (V_R) is 5V.
• Output (Detector Side): The average output current (I_O(AVG)) should not exceed 8 mA, with a peak output current (I_O(PK)) limit of 16 mA. The output voltage (V_O) can range from -0.5V to +20V, and the supply voltage (V_CC) from -0.5V to +30V.
• Isolation & Thermal: The devices provide a high isolation voltage (V_ISO) of 3750 V_rms (tested for 1 minute). The operating temperature range (T_OPR) is exceptionally wide, from -55°C to +100°C. The maximum soldering temperature is 260°C for 10 seconds.

2.2 Electrical & Transfer Characteristics

These parameters are guaranteed over the operating temperature range of 0°C to 70°C unless otherwise specified.

• Input Characteristics: The typical forward voltage (V_F) of the LED is 1.45V at a forward current (I_F) of 16 mA, with a maximum of 1.8V. The forward voltage has a negative temperature coefficient of approximately -1.9 mV/°C.
• Output Characteristics: Key parameters include Logic High Output Current (I_OH), which is very low (leakage level, typically 0.001 µA at V_CC=5.5V), and supply currents in logic low (I_CCL, ~140 µA) and logic high (I_CCH, ~0.01 µA) states.
• Current Transfer Ratio (CTR): This is a critical parameter defining the efficiency of the optocoupler. The series is offered in different CTR grades:
  • EL0500: CTR min 7%, max 50% (typical test: I_F=16mA, V_O=0.4V).
  • EL0501 / EL0452 / EL0453: CTR min 19%, max 50% (typical test: I_F=16mA, V_O=0.4V).
  A lower guaranteed CTR at specific conditions (e.g., 5% for EL0500, 15% for others at V_O=0.5V) is also specified, ensuring functionality under less ideal conditions.
• Logic Low Output Voltage (V_OL): The maximum voltage at the output when the device is in the "ON" state. It is typically 0.18V and guaranteed to be below 0.4V or 0.5V depending on the load current (I_O).

2.3 Switching Characteristics

Measured under standard conditions (I_F=16mA, V_CC=5V, T_A=0 to 70°C), these parameters define the device's speed.

• Propagation Delay:
  • EL0500: Propagation delay time to logic low (t_PHL) and to logic high (t_PLH) is maximum 2.0 µs with a 4.1 kΩ load resistor (R_L).
  • EL0501 / EL0452 / EL0453: Faster switching with t_PHL and t_PLH maximum 1.0 µs using a 1.9 kΩ load resistor.
• Common Mode Transient Immunity (CMTI): This measures the device's ability to reject fast voltage transients between its input and output grounds. It is a crucial parameter for noise immunity in isolated systems.
  • EL0453: Offers superior performance with a minimum CMTI of 15,000 V/µs at a common-mode voltage (V_CM) of 1500V peak-to-peak.
  • EL0500 / EL0501 / EL0452: Have a typical CMTI of 1,000 V/µs at V_CM=10V p-p.
  CMTI is specified separately for the output held at logic high (CM_H) and logic low (CM_L) states.

3. Performance Curve Analysis

The datasheet references typical electro-optical characteristic curves. While the specific graphs are not provided in the text, standard curves for such devices typically include:

• Current Transfer Ratio (CTR) vs. Forward Current (I_F): Shows how efficiency changes with LED drive current, usually peaking at a specific I_F.
• CTR vs. Ambient Temperature (T_A): Illustrates the temperature dependence of the coupling efficiency, which generally decreases as temperature increases.
• Propagation Delay vs. Load Resistance (R_L): Demonstrates how switching speed is affected by the output load.
• Forward Voltage (V_F) vs. Forward Current (I_F): The standard I-V curve for the input LED.
• Output Saturation Voltage vs. Output Current: Shows the relationship between collector-emitter voltage and current when the phototransistor is saturated.

These curves are essential for designers to optimize circuit performance, select appropriate operating points, and understand device behavior under non-standard conditions.

4. Mechanical & Package Information

4.1 Pin Configuration and Function

The device uses an 8-pin SOP package. There are two primary pinout configurations corresponding to different part numbers:

• For EL0500 / EL0501:
  1. No Connection
  2. Anode (LED +)
  3. Cathode (LED -) 4. No Connection 5. Ground (GND) 6. Output (V_OUT) 7. Bias Voltage (V_B) - This pin is key for speed enhancement. 8. Supply Voltage (V_CC)
• For EL0452 / EL0453:
  1. No Connection
  2. Anode (LED +)
  3. Cathode (LED -) 4. No Connection 5. Ground (GND) 6. Output (V_OUT) 7. No Connection 8. Supply Voltage (V_CC)

The presence of the V_B pin (Pin 7) in the EL0500/01 allows external biasing of the photodiode, which is the mechanism for achieving higher speed. The EL0452/43 variants likely have this bias network internally configured.

5. Application Guidelines

5.1 Typical Application Circuits

The datasheet includes reference test circuits for measuring switching time and common-mode transient immunity (Figures 8 & 9). These circuits serve as a guide for implementation:

• Switching Time Test Circuit: Typically involves driving the input LED with a pulse generator through a current-limiting resistor. The output is connected to V_CC via a pull-up resistor (R_L = 4.1kΩ or 1.9kΩ as specified) and monitored with an oscilloscope. The propagation delay is measured between the 50% points of the input and output waveforms.
• Transient Immunity Test Circuit: Involves applying a high-voltage, fast-rising common-mode pulse (V_CM) between the shorted input pins (1-4) and shorted output pins (5-8). The output state is monitored to ensure it does not falsely toggle due to the transient.

5.2 Design Considerations

• LED Current Limiting: An external resistor must be used in series with the input LED to set the forward current (I_F). The value is calculated based on the supply voltage, the LED's forward voltage (V_F), and the desired I_F (often 16 mA for optimal speed/CTR).
• Output Load Resistor (R_L): The choice of pull-up resistor affects switching speed, power consumption, and logic levels. A smaller R_L provides faster rise times but increases power dissipation when the output is low. The datasheet specifies test conditions with R_L=4.1kΩ for EL0500 and 1.9kΩ for the others.
• Noise Immunity: For applications in electrically noisy environments (motor drives, industrial controls), selecting the EL0453 variant for its high guaranteed CMTI is critical. Proper PCB layout, with short traces and decoupling capacitors close to the device pins, is also essential.
• CTR Degradation: Like all optocouplers, the CTR of these devices will gradually decrease over time, especially when operated at high temperatures and high LED currents. Design should include sufficient margin to ensure circuit functionality over the product's intended lifetime.

6. Technical Comparison & Selection Guide

The EL045X/EL050X series offers a range of options tailored for different needs:

• EL0500 vs. EL0501 / EL0452 / EL0453: The primary difference is the Current Transfer Ratio (CTR). The EL0500 has a lower minimum CTR (7% vs. 19%), making it suitable for applications where the input drive current can be higher. The others offer higher sensitivity.
• EL0453 vs. Others: The EL0453 stands out due to its guaranteed minimum Common Mode Transient Immunity of 15 kV/µs. This makes it the preferred choice for high-noise isolation applications like switching power supply feedback loops or motor drive inverter gate drives, where voltage spikes are common. The other variants specify a typical CMTI of 1000 V/µs.
• Pin Configuration: The EL0500/01 have an active V_B pin (7), while the EL0452/43 have it as NC. This reflects internal architectural differences for speed optimization.

Selection Summary: Choose EL0453 for highest noise immunity. Choose EL0501/EL0452 for higher sensitivity and standard speed. Choose EL0500 for cost-sensitive applications where lower CTR is acceptable and drive current is not a constraint.

7. Packaging and Ordering Information

The devices are available in different packaging options to suit production needs.

• Standard Packaging: 100 units per tube.
• Tape and Reel Options: Available in TA or TB reel types, containing 2000 units per reel. This is suitable for automated surface-mount assembly.
• VDE Option: Parts can be ordered with VDE certification (indicated by the "-V" suffix).
• Part Numbering: The part number follows the format: EL050X(Z)-V or EL045X(Z)-V, where:
  • X = Device number (0,1 for EL050x; 2,3 for EL045x).
  • Z = Tape & Reel option (TA, TB, or blank for tube).
  • -V = Optional VDE certification.
  Example: EL0453(TA)-V denotes an EL0453 device in TA tape and reel packaging with VDE approval.

8. Principle of Operation

The device operates on the principle of optical coupling for electrical isolation. An electrical signal applied to the input side causes the infrared LED to emit light proportional to the current. This light traverses an insulating gap (typically a transparent dielectric) and strikes the photodetector on the output side. In this series, the detector is a photosensitive diode connected to the base of a high-speed transistor. The separate bias pin (V_B in some variants) allows pre-biasing the photodiode, which minimizes its junction capacitance. When light hits the photodiode, it generates a current that directly drives the base of the transistor, turning it on. This design avoids the large Miller capacitance associated with a standard phototransistor's base-collector junction, enabling much faster switching speeds—up to 1 Mbit/s. The optical path provides galvanic isolation, blocking high voltages (up to 3750 V_rms) and rejecting common-mode noise between the input and output circuits.

9. Application Scenarios

• Switch-Mode Power Supply (SMPS) Feedback Loops: Providing isolated voltage feedback from the secondary side to the primary side controller, requiring both speed for loop stability and high CMTI to withstand switching noise.
• Motor Drive Inverter Isolation: Isolating gate drive signals for IGBTs or MOSFETs in variable frequency drives. The high CMTI of the EL0453 is essential here to prevent false triggering from high dv/dt transients.
• Industrial Communication Interfaces: Acting as line receivers for isolated RS-485, CAN, or Profibus networks, protecting sensitive logic circuits from ground loops and surges.
• Telecommunication Equipment: Providing signal isolation in line cards or interface modules.
• Replacement for Low-Speed Phototransistor Couplers: Upgrading existing designs to achieve higher data rates without changing the board footprint (SO-8 compatible).
• Home Appliance Control: Isolating user interface microcontrollers from power switching sections (e.g., in washing machines, air conditioners).

10. Frequently Asked Questions (FAQ)

Q1: What is the main difference between the EL0500 and EL0501?
A1: The primary difference is the guaranteed minimum Current Transfer Ratio (CTR). The EL0500 has a lower minimum CTR (7% at specified conditions) compared to the EL0501 (19%). This means the EL0501 is more sensitive and can operate with slightly lower input LED current to achieve the same output, but the EL0500 may be sufficient and more cost-effective in circuits designed for higher drive currents.

Q2: When should I specifically choose the EL0453 variant?
A2: You should choose the EL0453 when your application operates in an environment with very high electrical noise and fast voltage transients between the isolated grounds. Its guaranteed minimum 15 kV/µs Common Mode Transient Immunity makes it essential for reliable operation in motor drives, high-power switch-mode power supplies, or industrial control systems where other variants might experience false switching.

Q3: How do I select the value for the LED current-limiting resistor (R_series)?
A3: Use Ohm's law: R_series = (V_supply - V_F) / I_F. V_F is the LED forward voltage (use 1.8V max for design margin). I_F is your desired operating current (16 mA is a common test condition for optimal performance). For a 5V supply: R_series ≈ (5V - 1.8V) / 0.016A ≈ 200 Ω. Always check power dissipation in the resistor.

Q4: Can I use these photocouplers for analog signal isolation?
A4: While possible, they are primarily designed for digital (on/off) signal isolation due to their transistor output and non-linear CTR characteristics. For linear analog isolation, a dedicated linear optocoupler or an isolation amplifier would be a more appropriate choice.

Q5: What is the purpose of the V_B pin on the EL0500/01?
A5: The V_B pin is used to apply a bias voltage to the internal photodiode. Properly biasing the photodiode reduces its junction capacitance, which is a major speed-limiting factor. This external bias network is what enables the high-speed performance (1 Mbit/s) of these devices compared to simple phototransistor couplers.