ADS7828: ADS7828EB/2K5 SCH review

Hi Tom:

Thanks for your reply, The pull ups(4.7K to 3.3V) for I2C is on the I2C mux side, it is not on this page.

I will download this tool to Calculate, and I will feedback to you for update.

For the pic you shared, the sample rate can be changed or not if we work on 100KHz/400KHz I2C in real application?

Best Regards

Lisa

Hi Lisa,

Yes - the sample rate can be changed.

Hi Tom:

I have another question, 

the 8ch use one ADC, does the sample rate 8K(SCL=400KHz) need be divided by 8  or not?

maybe my direction is wrong,so just double confirm with you about this question

Thanks

Best Regards

Lisa

Hi Lisa,

Yes - 50K is one channel.  Two channels is MAX 25k/CH, four channels is 12.5k/CH etc.

Hi Tom:

Sorry,maybe my description is confused.

I mean the value marked with red (from Datasheet)

1. e.g. 8KHz is the throughput frequency when SCL=400KHz, and this 8KHz is the sampling rate in calculation Tool when SCL=400KHz, Right?

2. Does I need use 8K/8=1KHz for each channel and put it in calculation tool to cal the relative Rin and Cin?

3. And I donot know how to get this 8KHz when SCL=400KHz?

Best

Lisa

Hi Lisa,

for Q1 & 2, Yes, you can use the 8k/8 for the calculator.  For Q3, the conversion time is fixed at 6uS and then the delay though the I2C transmission (writing the address + command byte and then doing the reading of the conversion result) uses the rest of the time delta based on the SCL speed.

Thanks Tom