Differences between EL817 vs PC817

When selecting an optocoupler for electronic circuit isolation, the EL817 and PC817 are two popular choices, each offering distinct advantages for specific applications. Both optocouplers provide essential signal isolation between different voltage domains, preventing electrical interference and ensuring safety in various circuits. While they share some similarities, such as their 4-pin DIP packaging and infrared LED coupled to a phototransistor, each model has unique features that make it better suited for particular tasks. 

In this comparison, we will explore the differences between the EL817 and PC817 in terms of their pinout, features, applications, and other factors, helping you determine the best option for your project needs.

What is EL817

The EL817 is an optocoupler consisting of an infrared emitting diode (LED) optically coupled to a phototransistor. Designed for electrical isolation, the EL817 is packaged in a standard 4-pin DIP, available in various configurations, including surface-mount options. Its main purpose is to provide a secure means of transferring electrical signals between two isolated circuits, making it ideal for interfacing microcontrollers with high-voltage AC or DC systems.

How to use EL817

To use the EL817, connect its input side (pins 1 and 2) to the control circuit with a current-limiting resistor for the LED. The output side (pins 3 and 4) is connected to the high-voltage side, typically with the collector tied to a pull-up resistor. This configuration allows the EL817 to switch the output based on the input signal, ensuring electrical isolation while transmitting the control signal effectively.

What is PC817

The PC817 is another optocoupler widely used for signal isolation, featuring an infrared LED coupled to a phototransistor in a 4-pin DIP package. Like the EL817, it ensures safe and noise-free transmission of electrical signals between circuits operating at different voltage levels. The PC817 is renowned for its reliability and compatibility with various industrial and consumer electronics applications.

How to use PC817

To use the PC817, connect its input terminals (anode and cathode) to the control circuit with a resistor to limit the LED current. On the output side, connect the collector to the power supply through a pull-up resistor and the emitter to the ground of the output circuit. This setup allows the PC817 to isolate and transfer control signals between circuits efficiently.

EL817 vs PC817: Pinout

EL817 vs. PC817: Pinout

Both EL817 and PC817 share a similar 4-pin DIP pinout:

• Pin 1 (Anode): Connects to the LED’s positive terminal.
• Pin 2 (Cathode): Connects to the LED’s negative terminal.
• Pin 3 (Emitter): Phototransistor output.
• Pin 4 (Collector): Connects to the high-voltage side via a pull-up resistor

EL817 vs PC817: Features

EL817 Features

Maximum Supply Current: 95µA

Maximum Offset Voltage:

200µV (EL8170)

1000µV (EL8173)

Maximum Input Bias Current: 3nA

Bandwidth (-3dB):

396kHz (Gain = 10)

192kHz (Gain = 100)

Single-Supply Operation:

Input Voltage Range: Rail-to-rail

Output Swing: Rail-to-rail

Compliance: Pb-Free (RoHS Compliant)

PC817 Features

Input Diode Forward Voltage: 1.25V

Maximum Collector-Emitter Voltage: 80V

Maximum Collector Current: 50mA

Cut-off Frequency: 80kHz

Rise Time: 18µs

Fall Time: 18µs

Packaging Options: Available in 4-pin DIP through-hole or SMT package

EL817 vs PC817: Application

EL817 Applications

• Measuring Instruments
• Home Appliances
• Telecommunication Devices
• Programmable Controllers

PC817 Applications

• Electrical Isolation Circuits
• Microcontroller I/O Switching
• Signal Isolation
• Noise Coupling Circuits
• Isolation Between Digital and Analog Circuits
• AC/DC Power Control

EL817 vs PC817: Equivalent

EL817 Equivalent

TLP181

LTV817

K817P

PC817 Equivalent

TLP321

MCT2E

LTV817

EL817 vs PC817: Advantages

EL817 Advantages

• Low Input Current Requirement:...

WS2811 vs. WS2812B: A Comprehensive Guide to Addressable LED Strips

Addressable LED strips have become a popular solution for creating dynamic and colorful lighting effects in various applications, from home décor to large-scale displays. Among the many options available, the WS2811 and WS2812B LED strips stand out for their flexibility, ease of use, and widespread compatibility with popular microcontrollers like Arduino and Raspberry Pi. However, understanding the differences between these two models is essential for selecting the right one for your project. This guide will compare the WS2811 and WS2812B LED strips, focusing on their key features, performance, and best use cases.

Overview of WS2811 and WS2812B

Both the WS2811 and WS2812B are addressable LED strips, meaning that each LED (or group of LEDs) can be individually controlled in terms of color and brightness. They share many similarities but also have crucial differences that affect their performance and application.

• WS2811: This model uses an external IC and operates at 12V. It controls groups of three LEDs at a time, making it suitable for larger installations where individual control of every LED isn’t necessary.
• WS2812B: Unlike the WS2811, the WS2812B has a built-in IC in each LED and operates at 5V. This allows for individual control of each LED, making it a preferred choice for detailed lighting designs where high precision is required.

Voltage Differences: 5V vs. 12V

One of the most noticeable differences between the WS2811 and WS2812B is their operating voltage. The WS2811 operates at 12V, while the WS2812B operates at 5V.

• WS2811 and Voltage Drops: Higher voltage means the WS2811 is more resistant to voltage drops over longer distances. This makes it a better option for installations where the power source is far from the LEDs, as the voltage drop will be less noticeable. For long runs of LED strips, the WS2811 offers more consistent performance without the need for frequent power injection points.
• WS2812B and Power Efficiency: On the other hand, the WS2812B’s lower operating voltage (5V) makes it more energy-efficient, which is particularly important for projects where power consumption is a concern. However, it is more sensitive to voltage drops, and longer strips may require additional power injection to maintain consistent brightness and color across the strip.

Control and Wiring

Both the WS2811 and WS2812B are controlled via a single data line, which simplifies wiring compared to older LED strips that required separate data and clock lines. However, there are some differences in how the control mechanisms work.

• WS2811: This strip controls groups of three LEDs with one external controller chip (IC). Because it controls LED clusters rather than individual LEDs, it is less suited for projects requiring high precision in color and brightness control. The WS2811’s data transmission protocol is similar to other serial data lines, and its wiring can be slightly more complex due to the need for an external IC.
• WS2812B: In contrast, the WS2812B features a built-in IC within each LED, allowing individual LED control. This provides much greater flexibility when designing custom lighting patterns, animations, or intricate displays. The WS2812B strip only requires three connections: 5V power, ground, and data. This simplicity makes it easier to set up and reduces the number of components needed in your project.

Power Consumption and Efficiency

When choosing between WS2811 and WS2812B, power consumption is a significant consideration, especially for battery-powered or energy-efficient projects.

• WS2811: The WS2811’s operating voltage of 12V generally leads to a higher overall power consumption than the WS2812B. However, because it controls groups of three LEDs at a time, the per-LED power consumption is effectively lower, making it a good choice for larger installations where energy efficiency over long distances is important.
• WS2812B: The WS2812B consumes more power per meter because of its lower voltage (5V) and individual...

The MAX485 IC by Analog Devices: An Efficient Low-Power RS-485 Transceiver

The MAX485 IC is a half-duplex RS-485/RS-422 transceiver, designed to optimize the balance between power consumption and high-speed data transmission. It’s based on Analog Devices’ expertise in precision electronics and caters to both industrial and commercial markets. One of its defining characteristics is its ability to function effectively over long distances while maintaining low power consumption, a crucial requirement in systems that need to preserve energy or use battery-powered setups.

Pin Configuration and Operation

The MAX485 has an 8-pin configuration:

1. RO (Receiver Output): Outputs the data received from the differential bus.
2. RE (Receiver Enable): Controls whether the receiver is active or disabled.
3. DE (Driver Enable): When high, enables the driver; when low, it places the driver in a high-impedance state.
4. DI (Driver Input): Sends data to the driver for transmission on the bus.
5. GND: Ground.
6. A & B (Differential Inputs/Outputs): The two differential signal lines used for data transmission.
7. Vcc: Supply voltage pin, typically powered by a 5V source.

Low Power Consumption and Sleep Mode

One of the MAX485's standout features is its ultra-low power consumption in both active and standby modes. The device operates on a 5V power supply, consuming less than 300 µA during normal operation. Additionally, it enters a low-power shutdown mode when the driver and receiver are disabled, reducing the power draw to less than 1 µA, making it ideal for battery-powered or remote applications. This is a crucial advantage in scenarios like remote sensor monitoring or wireless communications, where devices need to conserve as much power as possible between communication intervals.

High Data Transmission Rate

The 2.5 Mbps data transmission rate of the MAX485 ensures fast and reliable communication, even in systems with significant data load. Whether it's used for real-time data monitoring, industrial automation, or digital communications, the MAX485 can handle the speed and accuracy demands of modern systems. This high-speed transmission capability allows for smooth integration into systems requiring near-instant data updates, such as SCADA systems, sensor networks, and building automation.

Robustness in Harsh Environments

The MAX485’s differential signaling technique is key to its robustness, especially in harsh industrial environments where electrical noise is a challenge. Differential signals, transmitted over twisted-pair cabling, are far less susceptible to external electromagnetic interference (EMI), ensuring data integrity even in areas with heavy industrial equipment. This makes the MAX485 ideal for environments such as factories, automotive, and power stations, where uninterrupted, error-free communication is critical.

Additionally, the IC can operate over a wide temperature range of -40°C to +85°C, which ensures that it can function in outdoor or industrial settings where temperature fluctuations are common.

Multi-device Bus Support

In many systems, communication isn't just between two devices but involves several nodes sharing data. The MAX485's support for up to 32 transceivers on a single bus allows for more complex and multi-device systems, such as distributed control systems (DCS) in industrial setups. This feature is particularly beneficial in industrial control systems, where multiple machines or devices need to communicate simultaneously.

Integrated Protection Features

The MAX485 is built to withstand potential damage from transient voltage spikes often encountered in harsh environments. The IC includes short-circuit protection and thermal shutdown features to safeguard the transceiver and prevent failures due to excessive heat or miswiring. This is essential in factory automation systems and motor controls, where voltage spikes and environmental stresses can lead to equipment failures.

Advantages of the MAX485 over Competing Solutions

1. Energy Efficiency: The low power consumption of the MAX485,...