Optoisolator 4 Channel Module TLP281

Features:

• Four Channels: Independent isolation for up to four digital signal pairs.
• High Isolation Voltage: Up to 5,000V RMS for strong protection.
• Compact and Space-Saving: Small footprint suitable for embedded applications.
• Low Power Consumption: Ideal for energy-efficient designs.
• High-Speed Transmission: Fast response for real-time digital systems.
• Low Coupling Capacitance: Minimizes signal distortion.
• Wide Operating Temperature: Operates reliably in harsh environments.
• RoHS Compliant: Meets environmental safety standards.
• Highly Reliable: Long operating life and low failure rate.
• Easy Integration: Simple interface for quick setup.

Description:

Each channel of the TLP281 contains an LED and a phototransistor separated by an isolation barrier. When a voltage is applied to the input, the LED emits light that is detected by the phototransistor, which then outputs a corresponding electrical signal. This optical transmission ensures complete isolation between input and output sides, protecting low-voltage circuits from high-voltage interference or damage.

Principle of Work:

• Voltage applied to the input pin powers the internal LED.
• The emitted light activates a phototransistor across the barrier.
• The phototransistor switches, reproducing the input signal on the output side.
• There is no electrical connection between input and output—ensuring full isolation.

Pinout of the Module:

• HVCC: Output base voltage (max 24V)
• HGND: Output ground
• GND: Input ground
• IN1–IN4: Digital input pins 1–4
• OUT1–OUT4: Isolated output pins 1–4
• NC: Not connected

Applications:

• Industrial control systems
• Motor driver and automation circuits
• Medical equipment (isolation)
• Digital signal isolation in microcontrollers
• Audio circuits (noise suppression)
• Power supply isolation

Example Circuit:

This example shows how to interface the TLP281 with an Arduino and a relay module.

Arduino Example Code:

int inputPin = 5;
int relayPin = 10;
int state = 0;

void setup() {
  pinMode(inputPin, INPUT);
  pinMode(relayPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  if (Serial.available() > 0) {
    state = Serial.read() - '0'; // Read value from Serial Monitor
  }

  digitalWrite(relayPin, LOW); // Default OFF

  if (digitalRead(inputPin) == HIGH && state == 1) {
    digitalWrite(relayPin, HIGH); // Turn ON relay
  }

  delay(100);
}

Upload this sketch to your Arduino. Open the Serial Monitor and send “1” to turn the relay ON or “0” to turn it OFF.

Technical Specifications:

• Isolation Voltage: 5,000V RMS (min)
• Input Voltage: 5V DC (max)
• Output Voltage: 55V DC (max)
• Output Current: 50mA (max)
• Operating Temp Range: -40°C to +110°C
• Storage Temp Range: -55°C to +125°C
• Rise/Fall Time: 18ns (max)
• Propagation Delay: 100ns (max)
• Power Consumption: 0.2mW (typical)
• Insulation Resistance: 10¹² ohms (min)
• CMTI: 10kV/μs (min)
• PCB Size: 25 x 24 mm

Comparison with MOC3041:

Resources:

• TLP281 Datasheet