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 high durability.

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

The Fotek SSR DC-DC is engineered to handle a wide range of DC control and load requirements. Below are the key technical details:

The SSR DC-DC typically has four terminals, as described below:

1. Control Signal Connection:

   • Connect the positive control signal to the Input (+) terminal.
   • Connect the ground of the control signal to the Input (-) terminal.
   • Ensure the control voltage is within the specified range (3-32 VDC).

2. Load Connection:

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

3. Power Supply:

   • Ensure the load voltage and current do not exceed the SSR's maximum ratings (5-200 VDC, 40 A).

4. Mounting:

   • Secure the SSR to a heat sink or panel to ensure proper heat dissipation, especially for high-current applications.

5. Testing:

   • Apply the control signal and verify that the load is switched on/off as expected.

• Heat Dissipation: Use a heat sink or cooling fan for high-current applications to prevent overheating.
• Isolation: Ensure proper electrical isolation between the control and load circuits.
• Polarity: Observe correct polarity for both control and load connections to avoid damage.
• Surge Protection: Use a diode or TVS (Transient Voltage Suppressor) across the load terminals to protect against voltage spikes.
• Avoid Overloading: Do not exceed the maximum load current or voltage ratings.

The SSR DC-DC can be controlled using an Arduino UNO. Below is an example circuit and code:

1. Connect the Arduino's digital output pin (e.g., pin 9) to the Input (+) terminal of the SSR.
2. Connect the Arduino's ground (GND) to the Input (-) terminal of the SSR.
3. Connect the DC load to the Load (+) and Load (-) terminals of the SSR.

// Example code to control a Fotek SSR DC-DC with an Arduino UNO
// This code toggles the SSR on and off every second.

#define SSR_PIN 9  // Define the digital pin connected to the SSR

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

void loop() {
  digitalWrite(SSR_PIN, HIGH);  // Turn the SSR on
  delay(1000);                  // Wait for 1 second
  digitalWrite(SSR_PIN, LOW);   // Turn the SSR off
  delay(1000);                  // Wait for 1 second
}

1. Can the SSR DC-DC be used for AC loads?

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

2. What happens if I reverse the polarity of the control signal?

   • The SSR will not function. Always ensure correct polarity to avoid damage.

3. Do I need an external resistor for the control signal?

   • No, the SSR has an internal resistor to limit the control current.

4. Can I use the SSR without a heat sink?

   • For low-current applications, a heat sink may not be necessary. However, for high-current loads, a heat sink is essential to prevent overheating.

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