HLW8110 Power Energy Metering Isolated Module

Description

Product Overview

The UGE HLW8110 Isolated Power & Energy Metering Module is a compact single-phase AC power-monitoring module based on the Hiliwei HLW8110 high-precision energy-metering IC. It is designed to measure AC voltage, current, active power, accumulated energy, power factor, and line frequency and provide the measured data to an external microcontroller through an isolated UART interface. The HLW8110 supports voltage/current RMS measurement, active-power and energy calculation, power-factor and frequency measurement, configurable gain, and digital calibration/compensation functions. 

The module uses a 5 mΩ shunt resistor for load-current sensing and a high-value resistor network for voltage measurement. The measurement section is separated from the external MCU interface through isolated power and optocoupler-based UART circuitry.

Key Features

• Based on Hiliwei HLW8110 energy-metering IC
• Single-phase AC power and energy measurement
• 5 A maximum recommended measurement current
• 5 mΩ shunt resistor for current sensing
• Direct AC voltage sensing through a high-value resistor divider
• Measures:
  • AC RMS voltage
  • AC RMS current
  • Active power
  • Accumulated active energy
  • Power factor
  • Line frequency
• High dynamic measurement range supported by the HLW8110
• Integrated energy accumulation engine
• Programmable measurement gain
• Internal voltage reference
• Internal oscillator
• UART communication
• Galvanically isolated MCU interface
• Isolated low-voltage power architecture
• 5 V external interface
• Compact PCB design
• Suitable for ESP32, ESP8266, STM32, Arduino and other microcontrollers
• Arduino Example and more info GitHub Repo

The HLW8110 supports 3.0–3.6 V or 4.5–5.5 V supply ranges and provides UART/SPI communication, depending on configuration. The IC manufacturer specifies high measurement performance under its stated test conditions, including <0.1% active-energy error over a specified dynamic range. These IC specifications should not be interpreted as the guaranteed accuracy of the complete assembled module without module-level calibration.

Measurement Specifications

Measurement Type: Single-phase AC

Maximum Recommended Current: 5 A AC

Current Sensor: 5 mΩ shunt resistor

Voltage Sensor: High-value resistor divider

Measured Parameters:

• Voltage RMS
• Current RMS
• Active power
• Active energy
• Power factor
• Line frequency

The HLW8110 is specifically designed for single-phase energy-metering applications and supports voltage/current sensing using low-value shunts or other current sensors such as CTs.

Example Shunt Dissipation

With the 5 mΩ shunt:

5 A → 0.125 W

This provides a conservative operating point for the module. The stated 5 A rating should be treated as the module’s recommended maximum measurement current, subject to the actual shunt component rating, PCB temperature rise, terminal rating, enclosure and installation conditions.

Electrical Interface

The external MCU connector provides:

• 5V — module power input
• GND — isolated low-voltage ground
• RX — UART receive
• TX — UART transmit

The UART signals are transferred through PC817 optocouplers, providing galvanic separation between the metering circuitry and the external MCU interface.

Communication

• Interface: UART
• UART signals: TX / RX
• Intended for direct connection to an external MCU
• Suitable for custom firmware, IoT controllers and energy-monitoring systems

The HLW8110 provides register access through UART and includes internal measurement, energy accumulation, calibration and monitoring functions.

Isolation

The module incorporates isolation in both the power supply and communication paths between the AC/metering section and the external low-voltage MCU interface.

The isolation architecture includes:

• Isolated power conversion
• PC817 optocouplers for UART TX/RX
• Separate measurement-side and MCU-side ground domains

Important: The AC measurement section itself is connected to the mains circuit. Therefore, the module should be treated as a mains-connected device and installed inside a suitable insulated enclosure.

Do not connect the isolated-side GND to the mains/measurement-side ground externally.

Power Supply

External Supply: 5 V DC

Interface Power: 5V / GND

The HLW8110 itself supports both 3.3 V and 5 V operating configurations. Your module uses a dedicated power architecture to provide the required metering and isolated interface supplies.

AC Connections

The screw terminal provides the mains/load connections shown on the PCB:

• L-IN — AC line input
• L-OUT — switched/measured line output to load
• N-IN — AC neutral connection

The load current passes through the onboard shunt resistor so that the HLW8110 can determine the current and calculate active power and energy.

Technical Specifications

Metering IC: Hiliwei HLW8110
Meter Type: Single-phase AC energy metering
Maximum Recommended Current: 5 A AC
Current Sensor: 5 mΩ shunt
Voltage Measurement: Resistor-divider based
Power Measurement: Active power
Energy Measurement: Active energy accumulation
Current Measurement: RMS current
Voltage Measurement: RMS voltage
Power Factor: Supported
Frequency Measurement: Supported
Communication: UART
External Interface: 5V, GND, RX, TX
UART Isolation: PC817 optocouplers
Power Isolation: Isolated power conversion
HLW8110 Supply: 5 V configuration
Measurement IC Package: SOP-8
PCB Type: Assembled module

The HLW8110 has three measurement channels and includes programmable gain, internal reference, energy accumulation, fault detection and digital calibration/compensation functions.

Applications

The module can be used as the metering front end for:

• Smart-home energy monitoring
• IoT energy-monitoring systems
• Smart plugs and sockets
• AC load monitoring
• Industrial equipment monitoring
• DIN-rail controllers
• Power-management systems
• PDU monitoring
• AC appliance monitoring
• ESP32 energy-monitoring projects
• STM32 energy-monitoring systems
• Arduino-based power meters
• Custom HMI and automation systems

These application areas are consistent with the intended applications of the HLW8110, including smart appliances, metering equipment, metering plugs, Wi-Fi plugs, charging equipment and PDUs.

What’s Included

• 1 × UGE HLW8110 Isolated Power & Energy Metering Module

The module is supplied as an assembled PCB.

External MCU, cables, connectors and mains wiring are not included unless specifically stated in the product listing.

Safety Notes

⚠️ Mains Voltage Warning

This module is designed to interface with hazardous AC mains voltage. The L-IN, L-OUT and N-IN connections are not SELV and must be treated as hazardous electrical connections.

• Do not touch the PCB while connected to mains power.
• Always disconnect mains power before handling or modifying the module.
• Use an appropriate insulated enclosure.
• Use appropriate fusing and over-current protection in the final installation.
• Maintain suitable creepage and clearance distances in the complete system.
• Do not connect oscilloscope grounds, USB grounds or other equipment directly to the mains-referenced measurement circuitry.
• The 5V/GND/RX/TX interface is intended to provide galvanic isolation, but the complete installation must still be designed and tested for the required safety/isolation standard.
• 5 A is the recommended maximum measurement current for this module.