AK8996 Datasheet, PDF (33/74 Pages) Asahi Kasei Microsystems – Pressure Sensor Interface IC

[AK8996/W]
7. Secondary Characteristics Adjustment for Pressure Sensor & AK8996 Offset and Sensitivity
Temperature
Specific procedures for adjusting the pressure sensor's temperature drift (secondary characteristics)
follow the sequence illustrated on this page.
Note) For enhanced adjustment accuracy, make an adjustment for both maximum operation
temperature and minimum operation temperature.
AC[1:0]
2ND[1:0]
OT2, OT1S,
OT1
ST2P, ST2N,
ST1PS, ST1P,
ST1NS, ST1N
2nd order function
generation block
Offset Temp.
+/- Gain
Temp.
STV
+40mV
VP
OT SW [0]
STSW[0]
0.5*VS
Gain Amp.1 Gain Amp.2 Gain Amp.3
VN
-40mV
ING
OCR, OCF
SCS, SC
IN SW [1:0]
Temperature
Sensor
2^nd order
characteristic
generator
EOT2[7:0] ^EST2P[7:0]
EST2N[7:0]
2^nd order
characteristic
tuning
1^st order
characteristic
tuning
2nd order function generation block
EOT1[9:0] EST1P[9:0]
EST1N[9:0]
2ND[1:0]
Secondary temperature characteristics for pressure sensor offset and sensitivity as shown in this equation
can be cancelled out with the AK8996's corresponding characteristics.
Secondary temperature characteristics for pressure sensor offset and sensitivity Vsen (T):
Vsen (T) = αT^2+βT+γ
Secondary temperature characteristics for AK8996 offset and sensitivity Vic (T):
Vic = [(g*a)T^2+(g*b)T+(g*c)]+[dT+e]=(g*a)T^2+(g*b+d)T+(g*c+e)
Quadratic function Linear function
In order to cancel the secondary temperature characteristics, the following measurements should be
conducted for at least three different temperatures (e.g., 25ºC, -40ºC, +105ºC).
MS1055-E-02
33
2011/12