AK8998 Datasheet, PDF (33/59 Pages) Asahi Kasei Microsystems – Preliminary

[AK8998/W/D]
VO pin
Cutoff
Ext. cap Freq.(Hz)
(nF) (Typical)
Fig Time (msec)
Typical
case
Worst
case
Note)
99% Settling time (ms) ( )
Typical
case
Worst
case
Note)
1000
1.090
0.300
0.400
672.4
962.5
220
4.955
0.300
0.400
147.9
211.7
22
49.55
0.300
0.400
14.79
21.17
2.2
495.5
0.300
0.400
1.479
2.117
0.22
4.96k
0.300
0.400
0.148
0.212
0.1
10.9k
0.300
0.400
0.067
0.096
Note) Worst case for external capacitance ±10% and lot variations.
99% Settling time (ms)
(+)
Typical
case
Worst case
Note)
672.7
148.2
15.09
1.779
0.448
0.367
962.9
212.1
21.57
2.517
0.612
0.496
2. VOUT pin S/(N+D)
Summarized in this table is the relationship between the VO pin’s external capacitance and
S/(N+D).
Note that the S/(N+D) should be 40dB or larger if 1.0% FS adjustment accuracy is required.
Sampling
Freq.(Hz)
VO pin
Ext. cap
(nF)
Cutoff
Freq.(Hz)
(Typical)
S/(N+D) characteristics
Typical case
Worst case
Note)
1000
1.090
68.8
1
220
4.955
22
49.55
55.6
35.6
2.2
495.5
15.8
220
4.955
75.6
10
22
2.2
49.55
495.5
55.6
35.6
0.22
4.96k
15.8
Note) Worst case for external capacitance ±10% and lot variations.
64.6
51.4
31.4
11.8
71.4
51.4
31.4
11.8
As mentioned in Sections "1. VOUT pin output voltage stabilization time" and "2. VOUT pin S/(N+D)",
the VO pin external capacitance value should be reduced to decrease the measurement time. For
increased S/(N+D), the VO pin external capacitance value should be greater.
On determining the VO pin external capacitance value, the various conditions should be thoroughly
reviewed according to the application requirements.
3) Pressure Detection Operation at Power-Up
Use caution when operating the pressure detection circuits.
VOUT pin output voltage is settled down based on the time constant determined by the internal
resistance 146kΩ and VO pin external capacitance Cap value (see 2) Finding the VO Pin External
Capacitance (Cap)). Note that errors may be detected during the time in which VOUT pin output is not
settled down to the voltage required according to the pressure applied.
MSxxxxx-E-00
- 32 -
2012/11