Microchip Technology ADM00333 Benutzerhandbuch
PIC18F87J72 Evaluation Board User’s Guide
DS51990A-page 14
© 2011 Microchip Technology Inc.
2.1.3
Measurement of Low Voltages
The circuit diagrams in the schematics section of Appendix A. “Schematics and Lay-
outs”, provide details on the resistor values used for the low voltage circuit. Table 2-6
provides a quick reference to resistor values in the low voltage section.
outs”, provide details on the resistor values used for the low voltage circuit. Table 2-6
provides a quick reference to resistor values in the low voltage section.
When measuring a low voltage signal on the input terminals of channels CH0 and CH1,
refer to Table 2-7 and Table 2-8. These tables provide the configuration of jumpers,
along with the amplitude of the voltage available at the various points. The low voltage
signal can be either an AC signal, a DC signal or a signal of any arbitrary wave shape.
refer to Table 2-7 and Table 2-8. These tables provide the configuration of jumpers,
along with the amplitude of the voltage available at the various points. The low voltage
signal can be either an AC signal, a DC signal or a signal of any arbitrary wave shape.
TABLE 2-6:
RESISTORS FOR LOW VOLTAGE MEASUREMENT
Register
Value (KΩ)
R34 and R36
1
R33 and R35
1
R37 and R39
1
R38 and R40
1
TABLE 2-7:
JUMPER SETTINGS FOR LOW VOLTAGE MEASUREMENT ON CH0
CH0 Jumper Position
ADC
Remark
Voltage
(Vrms)
JP1
JP2
JP3
JP4
ADC I/P
(Vrms)
ADC I/P
(Vpeak)
(Vpeak)
0.1
Short 2-3
Open
Open
Short
0.05000
0.05000
Internal Gain of 2 can be used for
better resolution
better resolution
0.2
Short 2-3
Open
Open
Short
0.10000
0.10000
0.5
Short 2-3
Open
Open
Short
0.25000
0.25000
1
Short 2-3
Open
Open
Short
0.50000
0.50000
1.1
Short 2-3
Open
Open
Short
0.55000
0.55000
Max Differential ADC I/P is 0.5V
TABLE 2-8:
JUMPER SETTINGS FOR LOW VOLTAGE MEASUREMENT ON CH1
CH1 Jumper Position
ADC
Remark
Voltage
(Vrms)
JP8
JP5
JP6
JP7
ADC I/P
(Vrms)
ADC I/P
(Vpeak)
(Vpeak)
0.1
Short 2-3 Open
Open
Short
0.05000
0.05000
Internal Gain of 2 can be used for
better resolution
better resolution
0.2
Short 2-3 Open
Open
Short
0.10000
0.10000
0.5
Short 2-3 Open
Open
Short
0.25000
0.25000
1
Short 2-3 Open
Open
Short
0.50000
0.50000
1.1
Short 2-3 Open
Open
Short
0.55000
0.55000
Max Differential ADC I/P is 0.5V
Note 1:
Input low voltage signal can be applied between pins 1 and 2 of the connector J4 or J5.