MAXREFDES14

Description

Introduction

The Sonoma (MAXREFDES14) energy measurement subsystem reference design provides galvanic isolation from the system with a single pulse transformer while using resistors as the sensing elements. The result is a small, cost-optimized board. AC measurement applications often require galvanic isolation to protect the system and user from high voltages. This is typically accomplished by either using bulky voltage/current transformers for sensors or by isolating the data and power interface to the measurement subsystem. These approaches, however, consume a considerable amount of space and come with hidden costs and design challenges.

The Sonoma design utilizes an isolated energy measurement processor (MAX78615+LMU); a multichannel, precision analog-to-digital converter (ADC) (MAX78700); a pulse transformer; optional 20MHz crystal oscillator, and the appropriate sense resistors for converting AC voltage and current into measurable signals. With the embedded load monitoring unit (LMU) firmware and nonvolatile storage of calibration and configuration data, Sonoma is a complete measurement subsystem ready for integration into any design.

Features & Benefits

Applications

• Lighting control systems
• Commercial and industrial automation
• Renewable energy systems
• Electric vehicle charging systems
• Smart home applications

Competitive Advantages

• On-chip nonvolatile storage of calibration and configuration parameters
• Full galvanic isolation with a single transformer
• Small board size
• Lower BOM cost

Features

• High-accuracy power measurement
• High-voltage galvanic isolation
• Preset gain/offset parameters
• On-board 4mΩ current sensing resistor with a good temperature coefficient
• On-board voltage sensing resistor divider with a ratio of 2667:1 with good temperature coefficient
• Universal AC input voltage range from 90 to 264VAC
• Pluggable terminals for AC (8A max)
• Small printed-circuit board (PCB) area
• Device drivers
• Example C source code
• Configuration files for Xilinx^® LX9 and ZedBoard^™ platforms
• Pmod^™-compatible form factor