Hi buddies,
I'm using ADS1247 in a voltage measurement, MCU is STM32F103. I found a problem that sometimes the noise is huge(only about 12 bit valid data) after the system power up, and sometimes the system is normal. The chance of problem increased if I increase the environmental temperature. And the problem state will not change(disappear or emerge) after power up.
I tried many times of change the init code to modify timing/sequence/delay, and can't fixed it.
After double check with the data sheet. I found some possible source, but not try it yet:
1. I use a 0.1 uF CAP for the REFOUT pin. That not what the DATASHEET suggest (1uf-47uf)
2. Both AVDD and DVDD use the same 3.3V. DATASHEET's example use a 5V for AVDD (FIG 85)
So Anybody can help to explain the mechnism of internal ref, why need a large filtering cap? Analog system will be better if use 5V power supply? (datasheet suggest 2.7V-5.25V OP range)