AK8998 Datasheet, PDF (28/59 Pages) Asahi Kasei Microsystems – Preliminary

[AK8998/W/D]
3. OSC Adjustment (completed when shipped in package form)
The intermittent operation control clock is adjusted to 1,000kHz.
Oscillation frequency can be adjusted without monitoring frequency directly.
The high level for the fixed period (2.0msec±1%) is inputted from the CSCLK pin after the writing of
an adjustment mode register (C address: 00h, data AM[3:0]= 3h). The internal clock pulses are
counted in the integrated counter circuit, and the count value is stored in the control register (C
address: 01h, data CT[7:0]). The adjustment data (address: 10h, data EFR[3:0]) for oscillation
frequency is calculated from the stored count value. The adjustment can be done within
1000kHz±5% accuracy by writing the adjustment data in EEPROM. Since the error of High period
turns into an adjustment error of frequency, please set period as 2.0ms±1%.
Twr_REG Tcont=2.0ms±1%
1
4
9
16
1
CSCLK
Pulse Count.
VOUT
Analog
Output
I2
The explanation of oscillation frequency adjustment data (address: 10h, data EFR[3:0]) is as
follows.
The count value stored in the control register (C address: 01h, data CT[7:0]) is read for the
ratio check. A ratio will be 0% (ideal value), when the High level period of CSCLK pin is 2
msec and the frequency of the internal oscillator is 1000 kHz. The ratio varies from 0% by the
error of High level period and the frequency variation of the internal oscillator. And the High
time which can be set up becomes a range from which a ratio will be -99% to 154%. Be
aware that the error is easily affected when the ratio is small. In addition, the counter value
shown as FF hex means overflow, please measure again by changing High level period.
Please set the adjustment data of oscillation frequency as the sum of the ratio of CT [7:0]
data and the ratio of EFR [3:0] data is close to 0%.
Address : 01 hex D[7:0]=CT[7:0]
CT[7:0]
Count value
Dec Hex
0 00
1 01
Bin
00000000
00000001
(time)
0
1
：：
：
：
98 62 01100010
98
99 63 01100011
99
100 64 01100100
100
101 65 01100101
101
102 66 01100110
102
：：
：
：
254 FE 11111110
254
255 FF 11111111
-
Ratio
(%)
0
-99
：
-2
-1
0
1
2
：
154
-
Comments
Default
Ideal value
Counter error
MSxxxxx-E-00
- 27 -
2012/11