The SSR-40DD Solid State Relay is an electronic switching device designed to control high-current DC electrical loads using a low-voltage DC control signal.
Featuring a 40A rated load current, 3–32V DC control input, and 5–60V DC output, this relay provides silent switching without mechanical contacts.
It is suitable for DC motor ON/OFF control, LED lighting, solenoid valves, industrial automation, and microcontroller-based projects.
Key Features
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40A Rated Load Current: Designed for switching compatible DC loads.
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DC-to-DC Operation: Controls DC loads using a DC control signal.
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3–32V DC Control Input: Suitable for low-voltage electronic control circuits.
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5–60V DC Load Output: Supports a variety of DC-powered equipment.
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Silent Switching: No mechanical clicking or moving contacts.
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Fast Electronic Switching: Suitable for automated ON/OFF control.
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Solid-State Design: No mechanical contact wear.
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Compact Housing: Suitable for industrial control panels.
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Screw Terminals: Convenient electrical connections.
Technical Specifications
| Parameter |
Specification |
| Model |
SSR-40DD |
| Product Type |
DC-to-DC Solid State Relay |
| Rated Load Current |
40A |
| Control Input Voltage |
3–32V DC |
| Load Output Voltage |
5–60V DC |
| Response Time |
≤10ms (supplier-listed) |
| Leakage Current |
≤2mA (supplier-listed) |
| Operating Temperature |
-20°C to +80°C |
| Dimensions |
Approx. 62 × 45mm (third dimension not confirmed) |
| Switching Type |
Electronic DC Switching |
| Mounting Type |
Panel Mount |
| Connection Type |
Screw Terminals |
| Cooling |
External Heatsink Recommended |
Terminal Configuration
| Terminal |
Function |
| 1 |
DC Load Terminal |
| 2 |
DC Load Terminal |
| 3 (+) |
DC Control Positive |
| 4 (−) |
DC Control Negative |
Note: Follow the polarity and terminal markings printed on the relay housing.
Microcontroller Compatibility
The SSR-40DD can be controlled using a suitable interface with:
- Arduino UNO and Mega
- ESP32 Development Boards
- ESP8266 Modules
- Raspberry Pi GPIO
- PLC Controllers with DC Outputs
Important: Direct GPIO operation depends on the controller's output voltage and current capability. A transistor driver or suitable interface may be required.
Applications
- DC Motor ON/OFF Control
- DC LED Lighting Systems
- Solenoid Valve Control
- Industrial Automation
- DC Power Switching
- Arduino and ESP32 Projects
- Raspberry Pi Automation
- PLC Control Systems
Important Notes
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DC Loads Only: This relay is designed for switching DC loads and is not suitable for AC loads.
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Polarity Sensitive: Follow the DC input and output polarity markings.
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Heatsink Required: Use an appropriately sized heatsink and thermal compound for high-current applications.
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40A Maximum Rating: Actual continuous current capacity depends on cooling, ambient temperature, and load characteristics.
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Inductive Loads: Use suitable flyback or transient suppression protection for motors, solenoids, and coils.
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GPIO Compatibility: Verify the input current requirements before connecting directly to a microcontroller.
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PWM Control: Do not use for high-frequency PWM motor speed control unless the manufacturer confirms suitable switching performance.
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Overcurrent Protection: Use an appropriately rated fuse or circuit breaker.
Package Includes
