MCP3909RD-3PH1 Microchip Technology, MCP3909RD-3PH1 Datasheet - Page 44

• 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

MCP3909 3-Phase Energy Meter Reference Design
DS51643B-page 40
Typically, phase A is the standard phase that the other two phases (B and C) are
calibrated to. However, there is no particular reason why this should be the case. Still,
there needs to be a way of signifying the standard phase. This document uses the
shorthand PHy<register name> to stand for an arbitrary register. For example,
PHy_W_GAIN stands for PHA_W_GAIN, PHB_W_GAIN, and PHC_W_GAIN.
The notation PH<s>… stands for the standard phase register whose value was
obtained from the three phase power meter during calibration setup C1. The notation
PH<u1> represents one of the two uncalibrated phases while PH<u2> represents the
other. In general, the calibration routines focus on the PH<u1> registers while the
PH<u2> registers would be calculated in the same way.
The meter constant is typically given in units of impulses per kilo-watt hour. As an
example, the calibration output frequency of CF, METER_CONSTANT =
3200 imp/kWh or 6400 imp/kWh.
Note:
To calibrate the offset for RMS voltage for a given phase at 1/10 of Vcal, the
meter must have power from one of the other two phases.
© 2008 Microchip Technology Inc.