User manual

Hardware Description
© 2011 Microchip Technology Inc. DS51990A-page 13
2.1.2 Measurement of High Voltages
The circuit diagrams in the schematics section of Appendix A. “Schematics and Lay-
outs”, provide details on the resistor values used for dividing the network of the input
voltage. Table 2-3 provides a quick reference to resistor values in the high voltage sec-
tion.
When measuring a high voltage signal on the input terminals of channels CH0 and
CH1, refer to Table 2-4 and Table 2-5. These tables provide the configuration of jump-
ers, along with the amplitude of the voltage available at the various points. The high
voltage can be in the universal range of input voltage ranging from 85-265 Volts
rms
(Vrms) at 50 Hz or 60 Hz.
TABLE 2-3: RESISTORS FOR HIGH VOLTAGE MEASUREMENT
Register Value (KΩ)
R23 and R30 330
R24 and R31 330
R25 and R32 120
R33 and R35 1
R37 and R39 1
TABLE 2-4: JUMPER SETTINGS FOR HIGH VOLTAGE MEASUREMENT ON CH0
CH0 Jumper Position ADC
Remark
Voltage
(Vrms)
JP1 JP2 JP3 JP4
ADC I/P
(Vrms)
ADC I/P
(Vpeak)
80 Short 1-2 Open Open Short 0.10230 0.14468 Internal Gain of 2 can be used
for better resolution
110 Short 1-2 Open Open Short 0.14066 0.19893
220 Short 1-2 Open Open Short 0.28133 0.39786
270 Short 1-2 Open Open Short 0.34527 0.48828
280 Short 1-2 Open Open Short 0.35806 0.50637 Max Differential ADC I/P is 0.5V
TABLE 2-5: JUMPER SETTINGS FOR HIGH VOLTAGE MEASUREMENT ON CH1
CH1 Jumper Position ADC
Remark
Voltage
(Vrms)
JP8 JP5 JP6 JP7
ADC I/P
(Vrms)
ADC I/P
(Vpeak)
80 Short 1-2 Open Open Short 0.10230 0.14468 Internal Gain of 2 can be used
for better resolution
110 Short 1-2 Open Open Short 0.14066 0.19893
220 Short 1-2 Open Open Short 0.28133 0.39786
270 Short 1-2 Open Open Short 0.34527 0.48828
280 Short 1-2 Open Open Short 0.35806 0.50637 Max Differential ADC I/P is 0.5V
Note 1: The precautions given need to be strictly adhered to, in order to avoid any damage to the evaluation
board and prevent electric shock hazard.
2: Input high voltage AC signal can be applied between pins 1 and 2 of the connector J4 or J5.
3: The resistors R26 and R27 should not be populated when pins 1 and 2 of J4 are connected to a high
voltage.
4: The resistors R28 and R29 should not be populated when pins 1 and 2 of J5 are connected to a high
voltage.
5: The resistors R26, R27, R28 and R29 can be used only when CT outputs are connected to the
connectors J4 and J5. In this case, these resistors act as a burden resistor to the CT secondary winding.