Other Parts Discussed in Thread: REF1933
Hello TI member :
I am trying to build a 14 bit environment by using ADS7052, could you help me to confirm whether my calibration flow was wrong or correct ?
My test flow are showed below, thank you for reading it patiently!
Test condition:
AVDD = REF1933 = 3.3V
DVDD = REF1933 = 3.3V
SCLK ~ 333.3 kHz
Purpose of this testing :
Check whether my calibrate function work correctly
Figure.1 is my "power up calibration" result, SDO from ADS7052 return code '0' while host provide 24 clock ( SCLK ~ 5.6 kHz )
Figure.1: Power up calibration
For more check on my calibration flow, figure.2 is my "offset calibration during normal operation" result.
Since my capture result was operated with VINP tie to AVSS , so SDO from ADS7052 return code '0' at first frame ( 18 clock ) seems correct.
Figure.2 : offset calibration during normal operation
After these two flow done, I tie ADS7052's VINP to REF1933's BIAS pin that provide AVDD / 2 and start to enter in CONV state to fetch transfer results with SCLK ~ 333.3 kHz.
Figure.3 is my calibrated results but it's seems didn't return '8192' as main code but '8176' ......
Figure.3 : Calibrated result with AVDD = REF1933 = 3.3V, DVDD = REF1933 = 3.3V, SCLK = 333.3 kHz , sample rate < 100 Ksps
My question :
1. Is the calibration flow have wrong ? ( such as power up calibration may not work correctly after REF1933 is being enable due to It's not the power up state ? )
2. From ADS7052's datasheet, figure.21 shows code '8125' as main code. Is the figure.21 as un-calibrated result ?
Thank you for your help.
B.R
Chen