Datasheet

MAX9880A
Low-Power, High-Performance
Dual I
2
S Stereo Audio Codec
48 ______________________________________________________________________________________
Offset Calibration Procedure
Perform before the first DC measurement is taken after
applying power to the MAX9880A.
1) Enable the AUX input (AUXEN = 1).
2) Enable the offset calibration (AUXCAL = 1).
3) Wait the appropriate time (see Table 17).
4) Complete calibration (AUXCAL = 0).
Gain Calibration Procedure
Perform the first time a DC measurement is taken after
applying power to the MAX9880A or if the temperature
changes significantly.
1) Enable the AUX input (AUXEN = 1).
2) Start gain calibration (AUXGAIN = 1).
3) Wait the appropriate time (see Table 17).
4) Freeze the measurement results (AUXCAP = 1).
5) Read AUX and store the value in memory to correct
all future measurements (k = AUX[15:0], k is typical-
ly 19,500).
6) Complete calibration (AUXGAIN = AUXCAP = 0).
DC Measurement Procedure
Perform after offset and gain calibration are complete.
1) Enable the AUX input (AUXEN = 1).
2) Wait the appropriate time (see Table 17).
3) Freeze the measurement results (AUXCAP = 1).
4) Read AUX and correct with the gain calibration value
5) Complete measurement (AUXCAP = 0).
Complete DC Measurement Example
f
MCLK
= 13MHz, slave mode, BCLK, and LRCLK are
not externally supplied.
1) Configure the digital audio interface for f
s
= 48kHz
(PSCLK = 01, FREQ1 = 0x0, PLL = 0, NI = 0x5ABE,
MAS = 0).
2) Disable jack sense (JDETEN = 0).
3) Enable the left and right ADC; take the MAX9880A
out of shutdown (ADLEN = ADREN = SHDN = 1).
4) Calibrate the offset:
a. Enable the AUX input (AUXEN = 1).
b. Enable the offset calibration (AUXCAL = 1).
c. Wait 40ms.
d. Complete calibration (AUXCAL = 0).
5) Calibrate the gain:
a. Start gain calibration (AUXGAIN = 1).
b. Wait 40ms.
c. Freeze the measurement results (AUXCAP = 1).
d. Read AUX and store the value in memory to cor-
rect all future measurements (k = AUX[15:0]).
e. Complete calibration (AUXGAIN = AUXCAP =
AUXEN = 0).
6) Measure the voltage on JACKSNS/AUX.
a. Enable the AUX input (AUXEN = 1).
b. Wait 40ms.
c. Freeze the measurement results (AUXCAP = 1).
d. Read AUX and correct with the gain calibration
value.
e. Complete measurement (AUXCAP = 0).
7) DC measurement is complete.
V
AUX
k
AUX
=
⎛
⎝
⎜
⎞
⎠
⎟
⎛
⎝
⎜
⎞
⎠
⎟
0 738
15 0
.
[:]
.
LRCLK (kHz) WAIT TIME (ms)
48 40
44.1 44
32 60
24 80
22.05 90
16 120
12 160
11.025 175
8 240
Table 17. AUX ADC Wait Times