(OC) outputs. Its minimum output voltage is approximately VS - 1V. Do not exceed the
maximum rated current of 300mA on this output.
AIx: Analog inputs
Iono Pi has two dedicated analog inputs (AI1 and AI2) on the low voltage terminal block.
The voltage input range is 0-30V. We use the MCP3204 4-channel 12-Bit A/D converter
from Microchip to convert the analog voltage to digital, with good resolution and sampling
speed.
The input impedance is approximately 200kOhm.
For convenience, a separate analog ground connection (A-GND) is avaliable on the
terminal block, next to AI1. A-GND should be used to connect the ground reference of the
analog input signals. Because the analog inputs are not galvanically isolated from the Iono
Pi's power supply, the A-GND line must be kept at the same voltage level of the negative
power supply line (VS-) and the GND connection on the terminal block. A-GND should
never be used as the negative power supply line or as a common ground for any other
purpose than the analog inputs ground reference.
The Iono Pi might be damaged if A-GND is not at the same voltage level of VS- and GND
and any amount of current is allowed to flow through A-GND.
Two additional inputs (AI3 and AI4) are available on an on-board expansion header (CN3)
for custom extensions. These inputs don’t have a voltage divider before the converter’s
inputs, and accept a voltage range of 0-3V, with an input impedance of approximately
200kOhm.
ANALOG INPUTS EXPANSION HEADER
WARNING
15
User Guide
