User manual

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.
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.
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)
0.1 Short 2-3 Open Open Short 0.05000 0.05000 Internal Gain of 2 can be used for
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)
0.1 Short 2-3 Open Open Short 0.05000 0.05000 Internal Gain of 2 can be used for
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.