Now I want to use ADC3 to collect the voltage of single-ended signals. I used IN1 channel to collect the reference voltage source of 1.5V and the internal channel to collect the internal reference voltage source of the chip respectively. The test results are as follows。The code value returned and the corresponding voltage size are shown in the figure below。
It can be found that the error of code is relatively large, because the bits of ADC can not reach 16 bits or what other reasons? Please advise
1 ACCEPTED SOLUTION
Accepted Solutions
Small and branching ground traces are not ideal. The VDDA pin should have a larger capacitor near it to prevent voltage drops. The datasheet says 1 uF in addition to the 0.1 uF. That will certainly help, as would using a ferrite bead before the VDDA/VREF+ supply.
Lots of other tips in that application note.
You will never get the full 16 bits of precision with no noise, but you can get 12-14 or so, depending on settings.
Small and branching ground traces are not ideal. The VDDA pin should have a larger capacitor near it to prevent voltage drops. The datasheet says 1 uF in addition to the 0.1 uF. That will certainly help, as would using a ferrite bead before the VDDA/VREF+ supply.
Lots of other tips in that application note.
You will never get the full 16 bits of precision with no noise, but you can get 12-14 or so, depending on settings.
How accurate is your reference voltage source? How accurate is your VREF+ voltage? The absolute error will mostly depend on these two values.
No voltage source is perfectly accurate. An error of 10 mV over 3.3V is 0.3%, which seems reasonable. It's certainly well within the specs of the AMS chip.
