MCP3901EV-MCU16 Microchip Technology, MCP3901EV-MCU16 Datasheet - Page 18

• Manufacturer Part Number: MCP3901EV-MCU16
• Description: BOARD EVAL FOR 2CH ADC MCP3901
• Manufacturer: Microchip Technology

Specifications of MCP3901EV-MCU16

• Number Of Adc's: 2
• Number Of Bits: 24
• Data Interface: SPI™
• Inputs Per Adc: 1 Differential
• Input Range: ±1 V
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: MCP3901
• Silicon Manufacturer: Microchip
• Application Sub Type: ADC
• Kit Application Type: Data Converter
• Silicon Core Number: MCP3901, PIC24F, PIC24H, DsPIC33, PIC18F86J55
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.2
DS51915A-page 18
CALIBRATION PROCEDURE
The power monitor should be calibrated to provide accurate measurements. Due to the
implemented signal processing technique, a single-point calibration is sufficient.
To achieve power factor compensations without modifying the hardware, the phase
delay block in the MCP3901 power monitor reference design is used. Through having
written a correct value in the Phase Delay register, one channel sample is delayed rel-
ative to the other channel sample.
Most of the phase errors are caused by phase delays
nents of the meter (i.e., RC filters, current transformers, etc.), from one of the two chan-
nels. This block can
delay is compensated, and measurement errors caused by power factor variations are
decreased.
The correct value for the Phase Delay register is determined automatically during the
calibration routine using the following method. First, determine the influence of the
Phase Delay register (kk) over measurement variation for the design. Five points are
enough to see a linear dependency, and by choosing the best fit, the Power Factor
compensation equation is obtained, as shown in Figure 2-8:
FIGURE 2-8:
Accuracy at Different Phase Angles.
The measurement variation is, in fact, the variation of the indication for the Active
Power value at 45 degrees and -45 degrees. These two points were chosen because
the measurement indication is varying almost linearly in this interval, as shown in
Figure 2-3.
-0.6
Measurements
Linear Best Fit
-0.4
Influence of the Phase Delay Register Over Measurement
induce
Power Factor Compensation Equation
an extra phase delay on the other channel, so the phase
-0.2
-1
-2
-3
-4
2
1
0
0
Measurement Variation (%)
induced
0.2
 2010 Microchip Technology Inc.
y = 4.9693x - 0.9836
by the various compo-
0.4
0.6