MCP3909-I/SS Microchip Technology, MCP3909-I/SS Datasheet - Page 29

• Manufacturer Part Number: MCP3909-I/SS
• Description: IC POWER METERING-1 PHASE 24SSOP
• Manufacturer: Microchip Technology

Specifications of MCP3909-I/SS

• Package / Case: 24-SSOP (0.200", 5.30mm Width)
• Input Impedance: 390 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.85V
• Current - Supply: 2.3mA
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Meter Type: Single Phase
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Supply Voltage Range: 4.5V To 5.5V
• Digital Ic Case Style: SSOP
• No. Of Pins: 24
• Interface Type: Serial, SPI
• Supply Voltage Max: 5.5V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: MCP3909EV-MCU16 - EVALUATION BOARD FOR MCP3909MCP3909RD-3PH1 - REF DESIGN MCP3909 3PH ENGY MTR
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

3.3
© 2009 Microchip Technology Inc.
CALCULATION() - CALCULATING ELECTRICAL PARAMETERS
All power parameters are calculated with the function Calculation(), which is executed
once every 3 cycles of the power grid. As shown in Figure 3-2, all calculations are
performed post DFT (direct fourier transform), in the frequency domain.
• RMS Voltage/current Of Each phase
• Phase Angle
• Measuring Line Frequency
• Active, Reactive, Apparent Power Of Each Phase
• Positive and Negative Active Power
• Positive/negative Reactive Power
• 4-quadrant Reactive Energy
• Total Active Power, Total Reactive Power, and Total Apparent Power
• Total Power Factor
• Voltage and Current Distortion Of Each Phase
• Voltage and Current Harmonic Contents Of Each Phase
FIGURE 3-2:
Note:
Algorithms for all calculations are shown in Appendix C. “Power
Calculation Theory”.
Calculation() Flow Chart.
phase sequence 1~3
sync. window process
sync. window process
Select sync. window
DTF transformation
DTF transformation
Voltage signal and
Current signal and
Calculate function
Calculate voltage
Calculate voltage
sine/cosine table
function and
RMS value
harmonic
loop
phase sequence 1~3
Calculate frequency,
Calculate combined
and compensation
Combined energy
Update loop array
power calculation
Calculate current
Calculate current
determine phase
pointer and data
End of function
Active/reactive
accumulation
RMS value
calculation
sequence
harmonic
power
length
end
Firmware
DS51723A-page 29