Other Parts Discussed in Thread: AMC1211-Q1,
Hello all,
I am using the INA826 to convert an differential voltage from the AMC1211-Q1 to an single output voltage to my uC.
Explanation of my circuit:
-"A1" is an analog voltage (0V to 5V) that I convert with the voltage divider to a maximum of 1.9V (the AMC1211-Q1 allows a maximum of 2V on VIN pin);
-"VOUTP1" and "VOUTN1" are subtracted in the INA826 and since I want the maximum input of 1.9V to be 3.3V at the input of my uC I have to apply an gain of 1.73 (1.73 x 1.9 = 3.29V), the gain resistor is 68KOhm (So gain = 1 + (49.4/68) = 1.73)
-I did my calculation based on the maximum input, 5V on voltage divider, translates into 1.9V in "VIN" pin of the AMC1211-Q1, and according to Figure 20 of the AMC datasheet, with VIN = 1.9V, VOUTP = 2.4V and VOUTN = 0.5V for this case. So far so good, I have tested this from 0V to 5V analog input and the differential output of this component is correct according the Figure 20 of the AMC datasheet.
-The Vout pin of the INA826 stops being correct after an analog voltage of around 1.9V (See table bellow for tests results)
So my question is, why isn´t the INA826 output performing like expected after it reaches about 1.9V?
Thank you for your time.
Analog Input before voltage divider [V] | AMC1211 VIN pin [V] | AMC1211 Output [V] | INA826 Expected Output [V] (Vout = 1.73 x (VOUTP - VOUTN) | INA826 Real Output [V] |
0.78 | 0.3 | VOUTP = 1.6 ; VOUTN = 1.3 | Vout = 1.73 x (1.6 - 1.3) = 0.52 | Vout = 0.51 |
1.83 | 0.7 | VOUTP = 1.8 ; VOUTN = 1.1 | Vout = 1.73 x (1.8 - 1.1) = 1.21 | Vout = 1.23 |
2.87 | 1.1 | VOUTP = 2 ; VOUTN = 0.9 | Vout = 1.73 x (2 - 0.9) = 1.9 | Vout = 1.89 |
3.92 | 1.5 | VOUTP = 2.2 ; VOUTN = 0.7 | Vout = 1.73 x (2.2 - 0.7) = 2.6 | Vout = 2.18 |
4.96 | 1.9 | VOUTP = 2.4 ; VOUTN = 0.5 | Vout = 1.73 x (2.4 - 0.5) = 3.29 | Vout = 2.44 |