I am using ADAS3022 to make a DAQ system to measure 0~24Vdc signal.
So I set PGIA to 0.16 (000), then input a DC voltage to IN0-COM and display in LabVIEW. VDDH = 15V, VSSH = -15V, DVDD = AVDD = 5V.
The test steps are below:
1. Input 10Vdc, the measured value is 0x33FD. (10 / 24.576) * 32768 = 13333 = 0x3415 ≈ 0x33FD.
Now, the input current is about 0mA. And the VDDH is 15V.
2. Input 15Vdc, the measured value is 0x4DF6. (15 / 24.576) * 32768 = 20000 = 0x4E20 ≈ 0x4DF6
3. Input 16Vdc, measured signal looks bad. (16 / 24.576) * 32768 = 21333 = 0x5355.
4. Input 19Vdc, measured value is much lower than actual value. (19 / 24.576) * 32768 = 25333 = 0x62F5.
Now, the input current is about 7mA. And the VDDH changed to 18.5V, but I set VDDH to 15V by ADP1613.
The schematic is blow:
Is there something wrong when I use ADAS3022?