Auxiliary voltage outputs
Iono Pi has an auxiliary 5Vdc voltage output pin on the terminal block, labeled 5VOUT, to
supply power to external 1-Wire devices or other low-power loads. Never exceed the
maximum rated current of 50mA on this output.
Another auxiliary voltage output pin, labeled VSOUT, is also available on the terminal
block. It is intended as the voltage source for small loads connected to the open collector
(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.
WARNING
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Iono Pi User Guide
