How to Use SSR DC - DC: Examples, Pinouts, and Specs

The Fotek SSR DC-DC is a Solid State Relay (SSR) designed specifically for DC applications. It enables the control of high-voltage DC loads using low-voltage control signals. Unlike traditional mechanical relays, the SSR DC-DC offers fast switching, high reliability, and no mechanical wear, making it ideal for applications requiring frequent switching or long operational lifespans.

• Industrial automation systems
• Motor control in DC circuits
• Battery management systems
• Solar power systems
• LED lighting control
• Robotics and mechatronics

The following table outlines the key technical specifications of the Fotek SSR DC-DC:

The Fotek SSR DC-DC has four terminals, as described in the table below:

1. Connect the Control Signal:

   • Attach the positive control signal (3-32 V DC) to the Input (+) terminal.
   • Connect the ground of the control signal to the Input (-) terminal.

2. Connect the Load:

   • Connect the positive terminal of the DC load to the Output (+) terminal.
   • Connect the negative terminal of the DC load to the Output (-) terminal.

3. Power the Control Circuit:

   • Ensure the control signal voltage is within the specified range (3-32 V DC).
   • When the control signal is applied, the SSR will switch the DC load on.

4. Verify Connections:

   • Double-check all connections to ensure proper polarity and avoid damage to the relay or load.

• Heat Dissipation: Ensure adequate heat dissipation for the SSR, especially when operating at high currents. Use a heatsink if necessary.
• Load Protection: Add a flyback diode across inductive loads (e.g., motors) to protect the SSR from voltage spikes.
• Control Signal Stability: Use a stable and noise-free control signal to avoid unintended switching.
• Isolation: Ensure proper electrical isolation between the control and load circuits to prevent damage or interference.

The Fotek SSR DC-DC can be easily controlled using an Arduino UNO. Below is an example circuit and code to toggle a DC load using a digital pin.

1. Connect the Input (+) terminal of the SSR to Arduino digital pin 9.
2. Connect the Input (-) terminal of the SSR to the Arduino GND.
3. Connect the DC load to the Output (+) and Output (-) terminals of the SSR.

// Define the pin connected to the SSR control input
const int ssrPin = 9;

void setup() {
  // Set the SSR pin as an output
  pinMode(ssrPin, OUTPUT);
}

void loop() {
  // Turn the SSR (and load) ON
  digitalWrite(ssrPin, HIGH);
  delay(1000); // Keep the load ON for 1 second

  // Turn the SSR (and load) OFF
  digitalWrite(ssrPin, LOW);
  delay(1000); // Keep the load OFF for 1 second
}

1. Can the SSR DC-DC handle AC loads?

   • No, this relay is designed specifically for DC loads. For AC loads, use an AC-rated SSR.

2. What happens if the control signal exceeds 32 V DC?

   • Exceeding the control voltage range can damage the SSR. Always stay within the specified range.

3. Can I use the SSR with an inductive load like a motor?

   • Yes, but you must use a flyback diode across the load to protect the SSR from voltage spikes.

4. Is the SSR polarity-sensitive?

   • Yes, ensure correct polarity for both the control and load connections to avoid damage.

By following this documentation, you can effectively integrate the Fotek SSR DC-DC into your projects for reliable and efficient DC load control.