MCP3909RD-3PH1 Microchip Technology, MCP3909RD-3PH1 Datasheet - Page 30

• 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
3.4.12
3.4.13
3.4.14
DS51643B-page 26
I_RMS
PHy_W_RAW
PHy_W
REGISTER 3-12:
This is the sum of all currents (note: algebraic sum of PHA_I_RMS, PHB_I_RMS, and
PHC_I_RMS, NOT RMS sum). This value should equal X A/LSB. When displaying total
RMS current, simply display the (decimal) value in this register with the decimal point
two digits in from the right. (Note this decimal point location of 0.01A LSB resolution is
specific for the 5(10)A, 220V rating that this meter is designed for). This register is
overwritten every LINE_CYC line cycles (written only once if calibration is enabled).
REGISTER 3-13:
These registers are the raw phase y active power as it represents the sum of each
phase y current A/D value times phase y voltage A/D value results over LINE_CYC line
cycles (each line cycle has 128 results). Each current times voltage multiplication
results in a 32-bit word. There are up to 256 line cycles with each line cycle being 128
results and each result being 32-bit. Thus, a 48-bit register is needed. This is the
register to be read during calibration for calculating the offset and gain values
associated with active phase y power, PHy_W_OFF, PHy_W_GAIN, and
PHy_W_GLSB. These registers are overwritten every line cycle, however if calibration
is enabled, updates will stop once LINE_CYC line cycles have elapsed.
REGISTER 3-14:
These registers are the value for phase y active power. The goal of calibration is to get
these registers values to equal X 0.1 mW/LSB. When displaying the active power for
phase y, simply display the value in these registers with the decimal point one digit in
from the right, in milli-watts. (Note this decimal point location, or LSB resolution of
0.1 mW, is specific for the 5(10)A, 220V rating that this meter is designed for). This
register is overwritten every LINE_CYC line cycles (written only once if calibration is
enabled).
PHC_W_RAW
PHA_W_RAW
PHB_W_RAW
I_RMS
Name
PHA_W
PHB_W
PHC_W
Name
Name
Bits
I_RMS REGISTER
PHY_W_RAW REGISTERS
PHY_W REGISTERS
24
Bits
Bits
48
48
48
32
32
32
Address
Address
Address
0x04C
0x07E
0x064
0x06A
0x070
0x076
0x07A
Cof
Cof
Cof
R
R
R
R
R
R
R
© 2008 Microchip Technology Inc.