wm8351 Wolfson Microelectronics plc, wm8351 Datasheet - Page 175

• Manufacturer Part Number: wm8351
• Description: Wolfson Audioplus? Stereo Codec With Power Management
• Manufacturer: Wolfson Microelectronics plc

Production Data
19.5 CALIBRATION
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The on-chip reference VREF provides a highly accurate reference voltage to the AUXADC. For best
measurement accuracy, the WM8351 provides a way to determine the voltage offset of the
AUXADC’s VREF buffer and the gain error introduced by scaling the AUXADC input. Measured data
can then be adjusted accordingly, eliminating these errors.
To determine the buffer’s offset, the AUXADC AUX3 input is disconnected from the AUX3 pin and
connected to the unbuffered VREF voltage. Note that input scaling must be used, (i.e.
AUXADC_SCALE3 = 10 or 11), in order to ensure that the AUXADC input is within the measurable
range. Measuring this voltage using the buffered VREF as the reference (AUXADC_REF3 = 1)
makes it possible to calculate the combined error.
R145 (91h)
Digitizer Control
(2)
Table 117 AUXADC Calibration
ADDRESS
BIT
2
AUXADC_CAL
LABEL
DEFAULT
0
Configure AUX3 input to be the
VREF supply for AUXADC
calibration.
0 = AUX3 input connected to
AUX3 pin
1 = AUX3 input connected to
unbuffered VREF
PD, June 2009, Rev 4.1
DESCRIPTION
WM8351
175