Description
Product Overview
The 5V 700mA AC-DC Buck Converter (Old Version) is an industrial-grade, encapsulated switching power supply module designed to convert high-voltage AC mains (85V–265V) into a regulated 5V DC output. Rated at 3.5 Watts (5V @ 700mA), this compact solution eliminates bulky traditional transformers and provides a safe, efficient, and space-saving way to power microcontrollers, relays, LED indicators, and IoT devices directly from a wall outlet .
Unlike consumer USB chargers, this bare-board module is designed for embedded integration. It features an isolated flyback topology, ensuring complete electrical separation between the hazardous AC side (Live/Neutral) and the low-voltage DC side (5V/GND). This isolation protects your sensitive electronics (Arduino, ESP32) and users from potential shocks .
This”Old Version” refers to the classic open-frame design (approx. 30x20x18mm) that has been a staple in DIY and industrial control for years. It includes comprehensive protection features—overcurrent, short-circuit, and temperature protection—making it a reliable choice for permanent installation in appliances, automation panels, and smart home devices .
Key Features
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Industrial-Grade Safety Isolation: High voltage isolation between AC input and DC output. Input and output are completely separated, ensuring user safety and protecting downstream low-voltage circuits .
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Wide Universal Input Range: Accepts 85V to 265V AC (50/60Hz) or DC 100V-370V, making it compatible with global mains standards (110V, 220V, 240V) without any jumper settings .
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Sufficient 3.5W Power Capacity: Provides a steady 5V output with 700mA of continuous current (800mA peak). Perfect for powering Arduino boards, ESP8266, relays, LED strips, and small sensors .
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“Old Style” Open-Frame Design: Features a classic non-encapsulated PCB with clear pin headers and mounting holes, allowing for easy soldering or glue fixation directly onto motherboards .
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Comprehensive Protection Suite: Built-in overcurrent protection (OCP), short-circuit protection (SCP), and over-temperature protection (OTP) prevent damage to the power supply and your devices during faults .
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Efficient Switching Topology: Achieves up to 85% conversion efficiency with low ripple (≤60mV), utilizing a high-frequency transformer to minimize size and heat compared to linear power supplies .
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Precision Voltage Regulation: Uses a 431 voltage reference circuit to maintain a stable DC 5V output (±0.2V) even when the input voltage fluctuates .
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Reliable Performance at Load: Guarantees stable operation across the full 0-700mA output range with an output voltage rise time of less than 100ms .
Technical Specifications (Old Version)
| Parameter | Operating Value |
|---|---|
| Input Voltage | AC 85V – 265V (50/60Hz) or DC 100V – 370V |
| Typical Input Current (110V/220V) | 0.0273A / 0.014A |
| Output Voltage (DC) | 5V (±0.2V / 4.8V–5.2V range) |
| Rated Output Current | 700mA (Continuous) |
| Peak Output Current | 800mA |
| Output Power (Max) | 3.5W |
| Conversion Efficiency | ≥80% (Typ. 85%) |
| Ripple & Noise | ≤ 60mV |
| Output Voltage Rise Time | ≤ 100ms |
| Operating Temperature | -20°C to +60°C |
| Humidity | 40% – 90% RH (non-condensing) |
| Dimensions (L x W x H) | Approx. 30mm × 20mm × 18mm |
| Mounting Style | Through-Hole Pins (2.54mm pitch) & Side Mounting Holes |
| Protection Features | OCP, SCP, OTP (Auto-restart for SCP, Latching for OCP/OTP) |





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