1. Introduction

The magnetic latching relay is a new type of relay developed in recent years. Unlike normal relay, the ON or OFF state of magnetic latching relay depends on the action of a permanent magnet, and the state switching is triggered by a certain width of pulse electric signal. Once set or reset, the relay remains in the current state even when powered off.

The magnetic latching relay features low power, steady performance, long service life, and low-temperature rise. It is perfect for applications requiring low power and high stability.

This DFRobot magnetic latching relay based on a special driver chip is small and easy to use, and can be used to remake home appliances or lighting controls, like smart electricity meters/lighting/sockets/switches, and so on.

2. Features

• Low power: 2.6mw-3.65mw
• Trigger Pulse Width: 2ms
• Holding function
• 3.3V & 5V supported

3. Applications

• Lighting Controls
• Smart Socket
• Smart Switch

4. Board Overview

5. Function Overview

6. Product Dimension

7. Specification

• Signal Level: 3.3V, 5V
• Power Voltage: 3.3V-5V DC
• Trigger Pulse Width: 2ms
• Static Current: 0.73mA - 0.8mA(@3.3V-5V）
• Coil Operating Current: 137mA(3.3V), 93mA(5V)
• Contact Resistance: ≤100mΩ (1A 6V DC)
• Contact Material: AgSnO2
• Max Switching Current: 10A
• Max Switching Power: 2770VA/300W
• Coil Rated Power: 0.4W
• Relay Action Time(@Rated Voltage): ≤8ms
• Relay Reset Time(@Rated Voltage): ≤5ms
• Operating Humidity Range: 5%-85%RH
• Operating Temperature Range: -40℃-85℃
• Product Dimension(Package Not Included): 42×32mm/1.65×1.26”

8. Tutorial

What's the purpose of this tutorial?

8.1 Requirements

• Hardware

  • DFRduino UNO R3 x 1
  • Gravity: Digital Push Button (Red) x 1
  • Gravity: Digital Push Button (Blue) x 1
  • M-M/F-M/F-F Jumper wires

• 8.2 Software

  • Arduino IDE

8.3 Control the ON/OFF of a Water Pump

Connection Diagram

Connection Description

• Magnetic Latching Relay
  • VCC to UNO 5V
  • GND to UNO GND
  • Pin A to UNO D3
  • Pin B to UNO D2
• Magnetic Latching Relay
  • Pin A to Water Pump Positive
  • COM to Battery Positive
• Battery
  • Negative to Water Pump Negative
• Blue Button
  • Pin D to UNO D13
  • Pin + to UNO 5V
  • Pin - to UNO GND
• Red Button
  • Pin D to UNO D4
  • Pin + to UNO 5V
  • Pin - to UNO GND

Sample Code

Press down the blue button, the water pump turns on. Press down the red button, it turns off.

int INA = 3;
int INB = 2;
int buttonA = 13; //Set Button A as blue button, connect to Pin 13 
int buttonB = 4; //Set Button B as red button, connect to Pin 4 

void setup() {
  pinMode(INA, OUTPUT);
  pinMode(INB, OUTPUT);
  pinMode(buttonA, INPUT);
  pinMode(buttonB, INPUT);
}
void loop() {
  if (digitalRead(buttonA) == HIGH) 
    {
      digitalWrite(INA, HIGH); 
      delay(2); //2ms pulse signal 
      digitalWrite(INA, LOW); 
    }
  if (digitalRead(buttonB) == HIGH) 
      digitalWrite(INB, HIGH);
      delay(2);//2ms pulse signal 
      digitalWrite(INB, LOW);
  }
}

Expected Results

When the program is downloaded, press down the blue button, the water pump turns on. Press down the red button, it turns off.

9. Notes

1. The factory state of magnetic holding relay is reset state, but it may change to set state due to impact during transportation or installation, so please change the state to set or reset according the actual needs when using (when the power is connected).

2. To ensure the set or reset of the magnetic holding relay, the excitation voltage applied to the coil must reach the rated voltage, and the pulse width must be greater than 4ms. the set and reset coil should not be powered simultaneously. Do not apply voltage to the coil for a long time (more than 1 minute).

3. In the process of product transportation, storage and application, please keep the product away from the strong magnetic field to avoid the change of set and reset voltage.

FAQ

For any questions, advice or cool ideas to share, please visit the DFRobot Forum.

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