ADS9110: The small signal output is incorrect

Hi Jiyu,

Thanks for your message! Some questions:

1. Where is your input signal coming from?
   1. How rapidly is it changing?
   2. Is there an RC on the input? 
2. Does the output change when you set the input to DC 0.6V and then 0V, for example?
3. What is the source/circuit of REFP? Is it low noise as described in datasheet section 7.3.1.2

Best regards,

Samiha

Where is your input signal coming from?

1. How rapidly is it changing?     ------------- I input a stable voltage and output it directly from a regulated power supply 
   1. Is there an RC on the input?     ------           no
2. Does the output change when you set the input to DC 0.6V and then 0V, for example?         ------The output data has changed, but it fluctuates around 0.6V with little fluctuation    
3. What is the source/circuit of REFP? Is it low noise as described in datasheet section 7.3.1.2   ---  REFP input is a reference 3V power supply

Hi Jiyu,

Thanks for your response. For the original voltage decrease you were trying to see, how much is the voltage changing by? Like it is going from 0.6V to 0.5V or?

Could you share a screenshot of all 4 of your SPI lines (including /CS and SDI)? And also CNVST, /RST, and RVS?

Best regards,

Samiha

我做了一个程序，将ADS9110采集的信号用DA输出，下面是输出的波形

the yellow is RVS, the blue is CS

the yellow is RVS ,the blue is CLK

the yellow is RVS ,the blue is CNT

I have created a program to output the signal collected by ADS9110 using DA. Below is the waveform of the output

the yellow is DI, the blue is CLK

the yellow is RVS, the bule is reset

The RESET signal is only sent once when powered on

the yellow is CLK, the blue is CS

Hi Jiyu,

Thanks for providing these. The interface looks okay. In this photo, is the yellow signal your input signal?

Here, in the blue signal, it looks like your DAC may be railing on the negative rail. Which DAC are you using? Could you share the schematic?

Could you check if the raw ADC output codes are changing and reaching 0V equivalent codes (0x0)? Or is it railing at 0.6V equivalent code (~0x0CCCD)?

Best regards,

Samiha

DAC should be fine, because I have previously printed out the data read from ADS9110, and the results matched the output of my DAC. When the input was below 0.6V, the data read was always around 0.6V.

Thks for ypur replay

But Why the input signal must be 0.5~2.5V instead of 0~3V (0~Vref)