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The Hi-Link HLK-PM03 3.3V/3W Switch Power Supply Module is an encapsulated AC-DC step-down power converter designed to safely supply low-voltage 3.3V logic circuits directly from household mains AC power. Eliminating the need for separate 5V-to-3.3V regulators or bulky external wall adapters, the HLK-PM03 packs a complete 3W switched-mode power supply (SMPS) into a tiny, plastic-potted enclosure.

Operating across a universal AC input voltage range from 90V AC to 264V AC (50Hz/60Hz), it delivers a stable, regulated 3.3V DC output rail with up to 900mA continuous output current. High-grade internal isolation ($3000\text{V AC}$ input-to-output) insulates delicate processing units (such as ESP8266, ESP32, or STM32 chips) from high-voltage grid spikes and noise. Its small profile fits easily inside standard electrical wall switch boxes, making it a favorite for native 3.3V smart home relays, IoT sensor nodes, and space-constrained smart appliances.

Key Features and Benefits

• Native 3.3V Output: Directly powers 3.3V microcontrollers (ESP32, ESP8266, STM32) without requiring additional step-down regulators.

• Ultra-Compact PCB-Mount Footprint: Fully potted plastic casing plugs into standard through-hole PCBs or prototyping boards, saving valuable board space.

• Global Universal AC Input Range: Accepts $90\text{V AC}-264\text{V AC}$ ($50/60\text{Hz}$), making it fully compatible with electrical grids worldwide.

• Regulated 3.3V 900mA (3W) Output: Supplies clean, low-ripple $3.3\text{V DC}$ output with tight voltage accuracy ($\pm 0.2\%$).

• High Electrical Isolation & Safety: Provides $3000\text{V AC}$ input-to-output isolation to safeguard downstream microcontrollers and user-facing controls.

• Built-In Hardware Protections: Features integrated overload, short-circuit, and thermal protections that automatically recover when fault conditions are removed.

• Ultra-Low Standby Power: Consumes less than $0.1\text{W}$ under no-load conditions, satisfying strict energy efficiency standards for always-on devices.

Technical Specifications

Pinout & Wiring Guide

The HLK-PM03 features 4 through-hole PCB pins clearly labeled on its housing:

Input Side (High Voltage AC):

• AC / L (Pin 1): Connect to Live / Phase mains input wire ($90\text{V}-264\text{V AC}$).

• AC / N (Pin 2): Connect to Neutral mains input wire.

Output Side (Low Voltage DC):

• -V0 / GND (Pin 3): Ground / Negative output rail ($0\text{V DC}$).

• +V0 / +3.3V (Pin 4): Regulated $+3.3\text{V DC}$ positive output rail.

Safety Warning: The AC input side carries high line voltages ($110\text{V}-230\text{V AC}$) that pose severe electrical shock hazards. Maintain proper PCB isolation/creepage distances, insulate all mains connections, and ensure mains power is disconnected before handling or installing the module.

Applications

• Native 3.3V Smart In-Wall Switches: Directly powers ESP8266/ESP32 Wi-Fi relay boards concealed inside standard gang boxes and light switches.

• IoT Sensor Nodes: Delivers continuous low-power supply for Wi-Fi, Bluetooth, and Zigbee sensor devices plugged directly into grid power.

• Compact Home Automation Hubs: Serves as an internal power supply for small home automation modules and smart sockets.

• DIY Custom Power Supplies: Ideal for embedding directly into custom project enclosures where using external wall adapters is undesirable.

Package Includes

• 1 x Hi-Link HLK-PM03 3.3V/3W AC-DC Switch Power Supply Module

Shipping & Delivery

• Free shipping on orders above ₹999 across India

• Dispatched within 1-3 business days

• Expected delivery: 3-7 business days depending on location

• Secure packaging to ensure safe transit of electronic components