5-Pin SOP High-Speed 10Mbit/s Logic Gate Photocoupler ELM6XX Series Datasheet - English Technical Document

1. Product Overview

The ELM6XX series represents a family of high-performance, high-speed logic gate photocouplers designed for demanding digital isolation applications. These devices integrate an infrared emitting diode optically coupled to a high-speed integrated photodetector with a logic gate output stage, featuring a strobable output capability. Packaged in a compact 5-pin Small Outline Package (SOP), they conform to a standard industry footprint, facilitating easy integration into existing designs and PCB layouts.

The core function of this component is to provide galvanic isolation between two electrical circuits while transmitting digital logic signals. This isolation is crucial for breaking ground loops, protecting sensitive logic circuits from voltage spikes and noise present in other parts of a system, and ensuring safety in applications with high common-mode voltages.

1.1 Core Advantages and Target Market

The ELM6XX series is engineered with several key advantages that make it suitable for modern electronic systems. Its high-speed capability of 10 Mbit/s enables its use in fast data communication interfaces. The devices guarantee performance across a wide operating temperature range from -40°C to +85°C, ensuring reliability in industrial and automotive environments. A high isolation voltage of 3750 V_rms provides robust protection. Furthermore, the series is compliant with major environmental and safety standards, including being halogen-free, Pb-free, RoHS compliant, and approved by UL, cUL, VDE, SEMKO, NEMKO, DEMKO, and FIMKO.

The primary target markets and applications include:

• Industrial Automation: For isolating PLC I/O, motor drives, and sensor interfaces from control logic.
• Telecommunications & Data Transmission: In line receivers and data multiplexing systems to eliminate noise.
• Power Electronics: As a reliable replacement for pulse transformers in switching power supply feedback loops.
• Computer Peripherals: For interfacing between systems with different ground potentials.
• General Digital Interface: For level translation and isolation between logic families such as LSTTL, TTL, and 5V CMOS.

2. In-Depth Technical Parameter Analysis

This section provides a detailed, objective interpretation of the key electrical and performance parameters specified in the datasheet. Understanding these parameters is critical for proper circuit design and ensuring reliable operation.

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the stress limits beyond which permanent damage to the device may occur. These are not operating conditions.

• Input Forward Current (I_F): 50 mA. Exceeding this current will likely destroy the internal Infrared Emitting Diode (IRED).
• Input Reverse Voltage (V_R): 5 V. The IRED is sensitive to reverse bias; this limit must be strictly observed.
• Supply Voltage (V_CC) & Output Voltage (V_O): 7.0 V. This defines the maximum voltage that can be applied to the output side's power and output pin.
• Isolation Voltage (V_ISO): 3750 V_rms for 1 minute. This is a key safety parameter, tested with input pins (1,3) shorted together and output pins (4,5,6) shorted together. It certifies the dielectric strength of the internal insulation barrier.
• Operating & Storage Temperature: The device is rated for -40°C to +85°C operation and -55°C to +125°C storage.
• Soldering Temperature: 260°C for 10 seconds. This is important for PCB assembly processes using reflow soldering.

2.2 Electrical Characteristics

These parameters define the device's performance under normal operating conditions (T_A = -40°C to 85°C unless noted).

2.2.1 Input Characteristics (IRED Side)

• Forward Voltage (V_F): Typically 1.45V, with a maximum of 1.8V at I_F=10mA. This is used to calculate the required current-limiting resistor on the input side.
• Temperature Coefficient of V_F: Approximately -1.9 mV/°C. The forward voltage drops slightly as temperature increases.
• Input Capacitance (C_IN): Typically 70 pF. This affects the high-frequency response and drive requirements of the input circuit.

2.2.2 Output & Transfer Characteristics

• Supply Currents: I_CCH (output high) is typically 6.0 mA, and I_CCL (output low) is typically 7.5 mA with V_CC=5.5V. These values determine the power consumption on the output side.
• High-Level Output Current (I_OH): The output can source a very small current (typ. 2.1 µA) when in the high state. This device is designed to drive high-impedance CMOS inputs, not to source significant current.
• Low-Level Output Voltage (V_OL): Typically 0.4V, maximum 0.6V when sinking 13mA. This defines a solid logic '0' level.
• Input Threshold Current (I_FT): Typically 2.4 mA, maximum 5 mA. This is the minimum input current required to guarantee the output switches to a valid low state (V_OL ≤ 0.6V) under the specified load conditions. It is a critical parameter for ensuring noise immunity.

2.3 Switching Characteristics

These parameters define the dynamic performance of the photocoupler, measured under standard conditions (V_CC=5V, I_F=7.5mA, C_L=15pF, R_L=350Ω).

• Propagation Delays (t_PHL, t_PLH): The time from the 50% point of the input current transition to the corresponding point on the output voltage transition. t_PLH (to high) is typically 50 ns, and t_PHL (to low) is typically 41 ns, both with a maximum of 100 ns. These delays limit the maximum data rate.
• Pulse Width Distortion (|t_PHL – t_PLH|): Typically 9 ns, max 35 ns. This asymmetry in rise/fall delays can narrow output pulses at high frequencies.
• Rise/Fall Times (t_r, t_f): Output rise time is typically 40 ns, and fall time is typically 10 ns. Faster edges are generally better for signal integrity.
• Common Mode Transient Immunity (CMH, CML): This is a critical parameter for isolation devices. It measures the immunity of the output state to fast voltage transients across the isolation barrier. The ELM601, for example, can tolerate a dV/dt of 5,000 V/µs with a 50V peak-to-peak common-mode signal without falsely changing state. The ELM611 offers even higher immunity (20,000 V/µs at 1000V_p-p).

3. Mechanical and Package Information

The device is housed in a 5-pin Small Outline Package (SOP). The pin configuration is as follows:

• Pin 1: Anode of the input IRED.
• Pin 2: Not connected (NC).
• Pin 3: Cathode of the input IRED.
• Pin 4: Ground (GND) for the output side.
• Pin 5: Output Voltage (V_OUT).
• Pin 6: Supply Voltage (V_CC) for the output side.

The datasheet includes a detailed package dimension drawing (in millimeters) which must be consulted for PCB footprint design. A recommended pad layout for surface mount assembly is also provided to ensure reliable soldering and mechanical stability.

4. Soldering and Assembly Guidelines

Proper handling and assembly are essential for reliability. The device is rated for a maximum soldering temperature of 260°C for 10 seconds, which aligns with standard lead-free reflow soldering profiles (e.g., IPC/JEDEC J-STD-020).

Key Considerations:

• Use the recommended pad layout to prevent tombstoning or misalignment during reflow.
• Adhere to the specified temperature profile to avoid thermal damage to the internal die and plastic package.
• Follow standard ESD (Electrostatic Discharge) precautions during handling, as the device contains sensitive semiconductor components.
• Store devices in a dry, controlled environment as per the storage temperature rating (-55°C to +125°C).

5. Packaging and Ordering Information

The ELM6XX series is available in different packaging options to suit production needs:

• Standard Option (None): Devices are supplied in anti-static tubes, with 100 units per tube.
• Tape and Reel Option (TA/TB): Devices are supplied on tape and reel for automated pick-and-place assembly, with 3000 units per reel. The 'TA' and 'TB' likely refer to different reel sizes or tape specifications.

Part Numbering System: ELM6XX(Z)-V

• XX: Specific part number (00, 01, or 11). These differentiate variants, likely based on Common Mode Transient Immunity ratings (e.g., ELM600, ELM601, ELM611).
• Z: Tape and reel option (TA, TB, or none for tube).
• V: Optional VDE approval marking.

6. Application Suggestions and Design Considerations

6.1 Typical Application Circuits

The primary application is digital signal isolation. A typical circuit involves a current-limiting resistor in series with the input IRED, connected to a logic signal. The output pin (V_OUT) is connected to V_CC via a pull-up resistor (R_L) and drives the input of the receiving logic gate. The value of R_L (e.g., 350Ω) and the load capacitance affect switching speed.

6.2 Critical Design Notes

• Input Current: Ensure the input current (I_F) meets or exceeds the maximum Input Threshold Current (I_FT) for guaranteed low output, but does not exceed the Absolute Maximum Rating. A typical operating I_F of 7.5mA to 10mA is common.
• Noise Immunity: For noisy environments, choose a variant (ELM601 or ELM611) with higher Common Mode Transient Immunity appropriate for the expected noise levels in the application.
• Power Supply Decoupling: Use bypass capacitors (e.g., 0.1 µF) close to the V_CC and GND pins on the output side to ensure stable operation and minimize switching noise.
• Truth Table: The device functions as a non-inverting buffer. A logic High (H) on the input (IRED on) produces a logic Low (L) on the output. A logic Low (L) on the input (IRED off) produces a logic High (H) on the output (due to the pull-up resistor).

7. Technical Comparison and Differentiation

Compared to standard 4N25/4N35 series photocouplers, the ELM6XX series offers significantly higher speed (10 Mbit/s vs. ~100 kbit/s) and superior Common Mode Rejection. Its logic gate output provides clean digital waveforms without the need for additional Schmitt trigger circuits often required with phototransistor outputs. The 5-pin SOP package is more compact than older DIP packages. The key differentiation within the ELM6XX series itself is the graded Common Mode Transient Immunity, allowing designers to select the appropriate cost/performance level for their specific noise environment.

8. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the maximum data rate I can achieve with this photocoupler?
A: The typical propagation delays allow for data rates up to 10 Mbit/s as specified. However, the actual maximum reliable rate in a system will be lower due to pulse width distortion and setup/hold times of the receiving logic. A conservative design might target 5-8 Mbit/s.

Q2: How do I choose between ELM600, ELM601, and ELM611?
A: The choice is primarily based on the required Common Mode Transient Immunity (CMTI). Use ELM600 for basic isolation with low noise. ELM601 (5,000 V/µs) is suitable for industrial motor drive and power supply applications. ELM611 (20,000 V/µs) is for very high-noise environments like high-power inverters.

Q3: Can I use this device to drive an LED or relay directly?
A: No. The output is designed to drive high-impedance CMOS or TTL logic inputs. Its current sourcing/sinking capability is limited (I_OH is very low, I_OL is specified at 13mA). To drive higher-current loads, an additional buffer or transistor stage is required.

Q4: What value of pull-up resistor (R_L) should I use?
A: The datasheet specifies test conditions with R_L=350Ω. This is a good starting point. A smaller resistor will provide faster rise times but increase power consumption and output current. A larger resistor will save power but slow down the rise time. The value must be chosen considering the load capacitance and required speed.

9. Practical Application Case Study

Scenario: Isolating a Microcontroller UART from an RS-485 Transceiver.
In an industrial sensor node, a 3.3V microcontroller's UART TX line needs to be isolated from a 5V RS-485 transceiver that connects to a noisy long-distance bus. An ELM601 can be used for this purpose. The microcontroller pin drives the IRED via a current-limiting resistor (e.g., (3.3V - 1.45V)/7.5mA ≈ 247Ω). The output side is powered by the 5V rail of the RS-485 transceiver. The V_OUT pin, pulled up to 5V with a 350Ω resistor, connects directly to the Driver Input (DI) pin of the RS-485 IC. This setup breaks the ground connection between the sensitive microcontroller and the noisy bus, protects the microcontroller from bus-induced transients, and handles the logic level translation from 3.3V to 5V. The high CMTI of the ELM601 ensures the digital signal remains intact despite noise on the bus.

10. Operating Principle

The device operates on the principle of opto-electronic conversion. An electrical current applied to the input side (pins 1 & 3) causes the Infrared Emitting Diode (IRED) to emit light. This light crosses an internal transparent isolation barrier (typically a molded plastic gap). On the output side, a monolithic silicon photodetector integrated circuit receives this light. This IC contains a photodiode, a high-gain amplifier, and a logic gate output stage (likely a totem-pole or similar structure). The amplifier converts the photocurrent into a voltage, which the logic stage buffers and outputs as a clean digital signal. The 'strobable output' feature mentioned likely refers to an internal latch or enable function that can hold the output state, but specific details require the full internal schematic.

11. Technology Trends

The trend in digital isolation is towards higher speeds, lower power consumption, smaller packages, and higher integration. While photocouplers like the ELM6XX remain excellent for many applications, alternative technologies based on capacitive (using SiO₂ barriers) or giant magnetoresistive (GMR) coupling are emerging. These can offer even higher data rates (>>100 Mbit/s), better timing symmetry (lower pulse width distortion), and longer lifetime as they have no LED to degrade. However, high-performance photocouplers continue to be widely used due to their proven reliability, high CMTI, simplicity, and cost-effectiveness for speeds up to tens of megabits per second. The development of devices like the ELM6XX series, with graded CMTI and halogen-free materials, reflects the ongoing evolution to meet stricter environmental and performance demands in modern electronics.