MAX11253 Datasheet, PDF (47/51 Pages) Maxim Integrated Products – Longer Battery Life for Portable Applications

MAX11253
16-Bit, 6-Channel, 64ksps, 6.2nV/√Hz PGA,
Delta-Sigma ADC with SPI Interface
SOC: System Offset Calibration Register (Read/Write)
Default = 0x00_0000
BIT NAME
B23
B22
B21
….
B3
B2
B1
B0
DEFAULT
0
0
0
….
0
0
0
0
The system offset calibration register is a 24-bit read/write register. The data written/read to/from this register is clocked in/out MSB
first. This register holds the system offset calibration value. The format is in two’s complement binary format. A system calibration
does not overwrite the SOC register.
The readback value of this register depends on CTRL3:CALREGSEL. A ‘1’ reads back the user programmed value. A ‘0’ reads back
the results of an internal register as described in CTRL3:CALREGSEL. The internal register can only be read during conversion.
The system offset calibration value is subtracted from each conversion result—provided the NOSYSO bit in the CTRL3 register is
set to ‘0’. The system offset calibration value is subtracted from the conversion result after self-calibration but before system gain
correction. It is also applied prior to the 1x or 2x scale factor associated with bipolar and unipolar modes. When a system offset
calibration is in progress, this register is not writable by the user.
SGC: System Gain Calibration Register (Read/Write)
Default = 0x7F_FFFF
BIT NAME
B23
B22
B21
….
B3
B2
B1
B0
DEFAULT
0
1
1
….
1
1
1
1
The system gain calibration register is a 24-bit read/write register. The data written/read to/from this register is clocked in/out MSB
first. This register holds the system gain calibration value. The format is unsigned 24-bit binary. A system calibration does not
overwrite the SGC register.
The readback value of this register depends on CTRL3:CALREGSEL. A ‘1’ reads back the user programmed value. A ‘0’ reads back
the results of an internal register as described in CTRL3:CALREGSEL. The internal register can only be read during conversion.
The system gain calibration value is used to scale the offset corrected conversion result—provided the NOSYSG bit in the CTRL3
register is set to ‘0’. The system gain calibration value scales the offset corrected result by up to 2x or can correct a gain error of
approximately -50%. The amount of positive gain error that can be corrected is determined by modulator overload characteristics,
which may be as much as +25%. When a system gain calibration is in progress, this register is not writable by the user.
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