MCP39F511A-SMBus-Battery-Monitor

This is a smart battery monitor based on Microchip 24-Bit Single Phase AC/DC Power Monitoring IC-MCP39F511A.

Device web page here.

Microchip solutions and products for Power and Energy Management here

MCP39F511A Features

The MCP39F511A device is a highly-integrated, complete single-phase power-monitoring IC designed for real-time measurement of input power for AC and DC power supplies, making it suitable for a wide range of consumer and industrial applications. It is capable of detecting the input voltage types in order to select DC or AC mode automatically. It includes dual-channel Delta-Sigma ADCs, a 16-bit calculation engine, EEPROM and a flexible 2-wire interface. Separate AC and DC calibration registers are provided, to ensure high-accuracy measurements in both modes. An integrated low-drift voltage reference with 7 ppm/°C in addition to 94.5 dB of SINAD performance on each measurement channel allows for better than 0.1% accurate designs across a 4000:1 dynamic range.

Additional Features

• Real-Time Measurement of Input Power for AC or DC Supplies
• Power Monitoring Accuracy capable of 0.1% error across 4000:1 dynamic range
• Automatic Sensing and Switching Between AC and DC Modes
• Built-In Calculations:
  • Active, Reactive, Apparent Power
  • Active and Reactive Energy Accumulation
  • True RMS Current, RMS Voltage
  • Line Frequency, Power Factor
• Dedicated Zero Crossing Detection (ZCD) Pin
• Dedicated PWM Output Pin
• Automatic Event Pin Control through Fast Voltage Surge Detection
• Fast Calibration Routines
• 2-wire UART: Baud Rate up to 115.2kbps
• 512 bytes User-accessible EEPROM through page read/write commands
• Low-Drift Internal Voltage Reference: 10 ppm/°C typical
• 28-lead 5x5 QFN package
• Extended Temperature Range -40°C to +125°C
• AEC-Q100 qualified

Device web page here.

Real life use

So, why do you need a smart battery monitor ? A standard "dumb" LiPo battery has no capability to measure the state of charge and no over-voltage and under-voltage protection, individual cell voltage measurement. In order to measure the energy stored in the battery an accurate ADC will be needed. To satisfy this need, MCP39F511A was chosen, because his Power Monitoring Accuracy is capable of 0.1% error across 4000:1 dynamic range.

The smart battery monitor it is currently active used in an Ardupilot plane Phoenix 2400. You can watch a complete video filmed with the plane here.

Applications

It is designed to be used in systems with SMBus communication like DJI smart batteries, Ardupilot flight controller systems and any other system that need a smart battery.

SMBus specification.

A practical example it's given with Ardupilot flight controller.

Choosing the smart battery type in Mission Planner Battery data reporting in Mission Planner

Firmware

The firmware it's currently under development and it is free to be improved. It supports basic functions for SMBus communication with flight controller. It is Arduino based and fully opensource.

Supported commands

The system can provide the standard smart battery commands:

const unsigned int Temperature            = 0;           // cmd 08   r     - °C
      unsigned int Voltage                = 0;           // cmd 09   r     - mV
        signed int Current                = 0;           // cmd 0A   r     - mA
        signed int AverageCurrent         = 0;           // cmd 0B   r     - avg current for 60 sec
      unsigned int RelativeStateOfCharge  = 0;           // cmd 0D   r     - %
      unsigned int AbsoluteStateOfCharge  = 0;           // cmd 0E   r     - %
      unsigned int RemainingCapacity      = 0;           // cmd 0F   r     - mAh
      unsigned int FullChargeCapacity     = 0;           // cmd 10   r     - mAh
      unsigned int RunTimeToEmpty         = 0;           // cmd 11   r     - min
      unsigned int AverageTimeToEmpty     = 0;           // cmd 12   r     - min
      unsigned int AverageTimeToFull      = 0;           // cmd 13   r     - min
const unsigned int ChargingCurrent        = 4000;        // cmd 14   r     - mA
const unsigned int ChargingVoltage        = 4200;        // cmd 15   r     - nCell * 4200mV
      unsigned int BatteryStatus          = 0;           // cmd 16   r     - status
      unsigned int CycleCount             = 10;          // cmd 17   r     - #
const unsigned int DesignCapacity         = 9000;        // cmd 18   r     - mAh
const unsigned int DesignVoltage          = 11100;       // cmd 19   r     - nCell * 3700mV
const unsigned int SpecificationInfo      = 0x0021;      // cmd 1A   r     - user
const unsigned int SerialNumber           = 12345;       // cmd 1C   r     - #

System Block Diagram

Application Block Diagram

PCB

The PCB design it's done using Altium designer.

TOP

BOTTOM

Schematics

Microcontroller

MCP39F511A

Buck Regulator

USB