MSP430F6726A: SD24_B differential input full scale

Yes. It is correct. 

Is there anything unclear? Please let me know if you have other question instead just click 'reject'.

Thank you for answering

Is it correct to understand that the conversion result is not clipped until the differential signal amplitude is 1.84Vp-p?

The answer below differs in that the amplitude of the differential signal is only clipped to half 0.94Vp-p.

Which is correct?

Best regards,

Hi, 

You can input 0-1.84V as a differential input which means the differential input zero point is 920mV. Of course the E2E you referred is a detailed answer for the differential. 

Hi,

Thank you for answering

Currently, it is being evaluated on the actual machine (80pin package product), but when a differential signal of 600mV was input to pin 1 and -600mV was input to pin 2 on ch0 of SD24_B, the upper word of the conversion result became FFFFh. The format setting for the output register is offset binary and left-justified.
The PGA gain setting is 1. From now on, the amplitude of the differential signal will be clipped at 1.2Vp-p. Why?

Best regards,

Hi, Could you use an oscilloscope to capture the input signal by differential probe? I want to check your input signal and your sw setting. Please capture the register setting. 

Hi

ch1 is the input trigger signal, and ch2 and ch3 are the SD24_B input signals.

At this time, the upper word of the conversion result is FFFFh.

The SD24FES bit of SD24BCTL0 is 0, which is 1 in active mode because it captured the state of LPM3.

Best Regards,

Hi,

Since the capture result of the register sent earlier is for LPM3 mode, the conversion result is the one when 0 level is input to AD.

Best regards,

The oscilloscope is -9xxmV to 9xxmV. Why did you say 1.2Vp-p?

Hi,

In the oscilloscope photo, the part where the cursor on the vertical axis is applied is the part where the level is lowered,

so it seems that SD24_B is sampling. It is + -600 mV at the cursor part.

Best regards,

Hi, 

Please refer to 

In which, you can find the internal circuit of the differential input. 

I think you may misunderstand the differential input since the oscilloscope showed the peak low voltage is -9xx mV. If you really confirm the ch2 input is -600mV to 600mV, please add the anti-aliasing filter so that it would generate a correct offset for the signal. I believe your signal's offset is not correct for ch2. 

Hi,

The conversion result when the DC voltage is input to the differential input pins 1 and 2 at the same time is attached.
The input level is clipped at ± 600 mV. Please tell me the reason for this.

Best regards,

SD24B2020-12-25.xlsx

Hi, 

What's the setting of SD24REFS? 

Hi,

SD24REFS setting is 1b.

best regards,

Hi, 

It seems a little strange. Could you try to disable the LPM3 mode and not to disable the internal reference voltage and capture the data?