HFD4/3-S Relay Module 3.3V–5V for STM32 Microcontrollers

HFD4/3-S Thin Relay Module — 3.3V to 5V, Low Power, Wide Compatibility

Take your electronics projects and industrial control systems to the next level with this compact HFD4/3-S Relay Module. Designed for seamless integration with STM32, 51, Arduino, Raspberry Pi, and other popular microcontrollers, this slim relay module delivers reliable signal switching and on/off load control in a space-saving form factor. Whether you're building automation circuits, prototyping embedded systems, or designing industrial control boards, this module is engineered to perform.

Key Features

• Wide Supply Voltage: Operates across a broad 3.3V–6V range, making it compatible with 3.3V and 5V microcontroller systems without additional level shifters.
• Low Power Consumption: Quiescent current of just 5µA; action current of 40mA — ideal for battery-powered and energy-conscious designs.
• High-Level Trigger: Triggered by a logic-high signal greater than 1.3V (and below VCC), with a low level threshold below 0.5V. Trigger current: 1.8mA.
• Generous Load Capacity: Supports up to 2A @ 30VDC and 0.5A @ 220VAC. Note: For voltages exceeding 60V, an insulation protection enclosure is strongly recommended to prevent electric hazard.
• Low Signal Insertion Loss: Signal insertion loss <0.3dB @ 1kMHz — perfect for signal switching applications where integrity matters.
• Compact & Thin Design: The slim HFD4/3-S relay fits tight PCB layouts and enclosures, saving valuable board space.

Technical Specifications

Who Is This For?

This relay module is a go-to component for:

• Hobbyists and makers building DIY automation projects
• Engineers prototyping embedded control systems
• Students learning microcontroller interfacing with STM32 or 51-series MCUs
• Industrial control applications requiring compact, reliable switching

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Please allow a 2–3% dimensional variance due to manual measurement. Actual product color may differ slightly from images depending on your monitor settings.

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Frequently Asked Questions

Q: Is the HFD4/3-S relay module compatible with 3.3V microcontrollers like STM32?

A: Yes! The HFD4/3-S relay module supports a wide supply voltage range of 3.3V to 6V, making it fully compatible with 3.3V microcontrollers such as STM32, as well as 5V systems like Arduino and 51-series MCUs. No additional level-shifting circuitry is required for standard 3.3V logic outputs.

Q: What is the maximum load this relay module can switch?

A: The relay module can handle a maximum load of 2A at 30VDC or 0.5A at 220VAC. For safety, always use an insulation protection enclosure when working with voltages above 60V to prevent electrical hazard.

Q: How much power does this relay module consume when idle?

A: The module draws an extremely low quiescent (standby) current of just 5µA, making it well-suited for low-power and battery-operated designs. When activated, the action current is 40mA.

Q: What trigger signal does this relay module require?

A: The relay is triggered by a high-level logic signal. The trigger voltage must be greater than 1.3V (and below VCC) to activate, and below 0.5V to deactivate. The trigger current is only 1.8mA, so it is easily driven directly from standard microcontroller GPIO pins.

Production & Packaging Notice

To maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.