Microchip Technology ADM00333 User Manual
Hardware Description
© 2011 Microchip Technology Inc.
DS51990A-page 15
2.1.4
Measurement of Current Signals
The circuit diagrams in the schematics section of Appendix A. “Schematics and
Layouts”, provide details on the resistor values used for the current measurement
circuit. Table 2-9 provides a quick reference to resistor values while measuring the
current signals. The output of Current Transformers (CTs) can be connected to the
input connector pins.
Layouts”, provide details on the resistor values used for the current measurement
circuit. Table 2-9 provides a quick reference to resistor values while measuring the
current signals. The output of Current Transformers (CTs) can be connected to the
input connector pins.
When measuring a current signal on the input terminals of channels CH0 and CH1,
refer to Table 2-10 and Table 2-11. These tables provide the configuration of jumpers,
along with the amplitude of the voltage available at the various points.
refer to Table 2-10 and Table 2-11. These tables provide the configuration of jumpers,
along with the amplitude of the voltage available at the various points.
TABLE 2-9:
RESISTORS FOR LOW VOLTAGE MEASUREMENT
Register
Value (KΩ)
R26 and R28
0.063
R27 and R29
0.063
R34 and R36
1
R33 and R35
1
R37 and R39
1
R38 and R40
1
TABLE 2-10:
JUMPER SETTINGS FOR CURRENT MEASUREMENT ON CH0
CH0 Jumper Position
ADC
Remark
CT Primary
Current
(Irms-A)
JP1
JP2
JP3
JP4
ADC I/P
(Vrms)
ADC I/P
(Vpeak)
(Vpeak)
0.1
Short 2-3
Open
Short
Open
0.00063
0.00089
Internal Gain of 2 can be used for
better resolution
better resolution
0.5
Short 2-3
Open
Short
Open
0.00315
0.00445
1
Short 2-3
Open
Short
Open
0.0063
0.00891
10
Short 2-3
Open
Short
Open
0.063
0.08910
20
Short 2-3
Open
Short
Open
0.126
0.17819
30
Short 2-3
Open
Short
Open
0.189
0.26729
Max Differential ADC I/P is 0.5V