MCP3909RD-3PH1 Microchip Technology, MCP3909RD-3PH1 Datasheet - Page 19

• Manufacturer Part Number: MCP3909RD-3PH1
• Description: REF DESIGN MCP3909 3PH ENGY MTR
• Manufacturer: Microchip Technology

Specifications of MCP3909RD-3PH1

• Main Purpose: Power Management, Energy/Power Meter
• Embedded: No
• Utilized Ic / Part: MCP3909, PIC18F2520, PIC18F4550
• Primary Attributes: 3-Ph, 220 VAC, In Case, LCD, USB, GUI
• Secondary Attributes: Opto-Isolated Interface for Safety
• Operating Voltage: 220 V
• Operating Current: 5 A
• Description/function: Energy Meter
• For Use With/related Products: MCP3909
• Lead Free Status / RoHS Status: Not applicable / Not applicable

3.1
© 2008 Microchip Technology Inc.
Chapter 3.
REGISTER OVERVIEW
There are over 100 possible registers associated with the MCP3909 3-Phase Energy
Meter Reference Design available via the RS-232 interlace on the PIC18F2520. The
registers are named to describe each phase, specific measurement, and in the case of
the calibration registers, the calibration function.
The intent of the calibration process is to yield output registers that are decimal
representation of the final energy, power, current or voltage value.
RMS Current and Voltage Registers
The PHy_I_RMS registers, post calibration, contain the decimal representation of RMS
current in A/LSB, 0.1A/LSB, or 0.01A/LSB. The PHy_V_RMS registers, post
calibration, contain the decimal representation of RMS voltage in 0.1V/LSB. The final
correction factor to convert these registers to these volts and amperes are located in
the PHy_I_RMS_GLSB and PHy_V_RMS_GLSB registers. These correction factors
can be automatically calculated and loaded by using the PC calibration software. The
exact representation depends on the meter values that are entered in the software. For
example, for a maximum current of 10A, the current is 0.01A/LSB.
Instantaneous Power Registers
The PHy_W and PHy_VA registers contain the decimal representation of the active
power (W) and apparent power (VA) post calibration. The reactive power calculation is
not implemented at this time.
The final correction factors to convert these registers to units of energy are located in
the _GLSB registers. These correction factors can be automatically calculated and
loaded by using the PC calibration software. The exact representation depends on the
meter values that are entered in the software. For example, at 10A and 220V, power in
the PHy_W register is 0.1 mW/LSB
Calibration Registers
The calibration registers fall into one of three categories: offset, gain, and LSB, denoted
by _OFF, _GAIN and _GLSB register names.
In addition there are two registers, CFNUM and CFDEN, that calibrate the output pulse,
CF.
PIC18F2520 Calculation and Register Description
METER REFERENCE DESIGN
MCP3909 3-PHASE ENERGY
DS51643B-page 15