MAX11270 Datasheet, PDF (39/46 Pages) Maxim Integrated Products – Integrated PGA

MAX11270
24-Bit, 10mW, 130dB SNR, 64ksps Delta-Sigma
ADC with Integrated PGA
SPI Self-Cal Offset Calibration Register (SCOC_SPI)
The Self-Cal Offset register is a 24-bit read/write register. The data written/read to/from this register is clocked in/out
MSB first. The format is always in two’s complement format. This register temporarily holds the self-cal offset calibration
value from the user. This value gets copied into the SCOC_ADC register. The value written to this register remains until
it is overwritten. This value gets invalidated for calibration after a system-calibration operation is requested. Any attempt
to write to this register during an active calibration operation will be ignored.
ADC Self-Cal Offset Calibration Register (SCOC_ADC)
This is a 24-bit read-only register. There are two ways this register value is updated. One way is if a self-cal operation is
requested. Another way is if a user writes a value to SCOC_SPI register, the value will then get copied into SCOC_ADC
from SCOC_SPI.
The self-cal offset value is subtracted from each conversion result if NOSCO = 0 in the CTRL5 register. The self-cal offset
value is subtracted from the conversion result before the self-calibration gain correction and before the system offset and
gain correction. It is also applied prior to the 2x scale factor associated with unipolar mode.
SPI Self-Cal Gain Calibration Register (SCGC_SPI)
The self-cal gain calibration register is a 24-bit read/write register. The data written/read to/from this register is clocked in/
out MSB first. The format is always in two’s complement format. This register temporarily holds the self-cal offset calibra-
tion value from the user. This value gets copied into the SCOC_ADC register. The value written to this register remains
until it is overwritten. This value gets invalidated for calibration after a system-calibration operation is requested. Any
attempt to write to this register during an active calibration operation will be ignored.
ADC Self-Cal Gain Calibration Register (SCGC_ADC)
This is a 24-bit read only register. There are two ways this register value is updated. One way is if a self-cal operation is
requested. Another way is if a user writes a value to SCGC_SPI register, the value will then get copied into SCGC_ADC
from SCGC_SPI.
The self-cal gain calibration value is used to scale the self-cal offset corrected conversion result before the system offset
and gain calibration values have been applied – provided NOSCG = 0 in the CTRL5 register. The self-cal gain calibration
value scales the self-cal offset corrected conversion result by up to 2x or can correct a gain error of approximately -50%.
The gain will be corrected to within 1ppm.
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