AK8999AW Datasheet, PDF (8/68 Pages) Asahi Kasei Microsystems – Pressure Sensor Control IC

CONFIDENTIAL
[AK8999A/AW/AD]
Block
STV
VDD track
Gain_Temp.
(STV)
LPF
S/H &
Level Shift
& SCF
Buffer
& SMF
Timing
Logic
Regulator
Pressure
Threshold
Detector1/2
Functions
Supply voltage and sensitivity temperature variation compensation circuit.
The pressure sensor sensitivity temperature drift and the supply voltage variation are
compensated by using the magnitude of supply voltage variation and the preloaded
compensation data in the EEPROM.
Sensitivity temp. drift. adj. Adj. range
-4000ppm/ ºC to +2500ppm/ ºC
Adj. step
18ppm/ ºC step
Anti-aliasing filter to eliminate the aliasing noise generated in the next sample and hold
circuit (S/H). The cutoff frequency is fc=60kHz.
S/H doubles the LPF output and samples and holds it. The output reference voltage can be
changed.
Output reference voltage adj. Adj. range
0.02*VDD to 0.98*VD
Adj. step
0.002*VDD /step
SCF is a low-pass filter without using the external capacitors. The cutoff frequency (fc:
1kHz /500Hz /250Hz) of the filter can be set by EEPROM.
Buffer to provide 1.111x output and produce a band limited output with low impedance.
146kΩ internal resistance and an external capacitor (C) make the LPF characteristics.
Change the external capacitance value according to the desired signal band for detection
using the following equation:
fc=1/(2*π* 146kΩ*C) (Hz)
SMF is a low-pass filter (fc=10kHz) for eliminating the clock noise generated by the
previous SCF. SMF is switched on or off in combination with the previous stage SCF
using the EEPROM data.
Generates timing sync signals for internal operation and sampling frequencies for sensor
output signals.
Sampling frequency (fs): 0.83kHz or 8.33kHz
Constant voltage generator to drive the sensor. The drive voltage can be selected from
the EEPROM depending on the supply voltage being used.
Drive voltage: 2.2V@VDD:3, 3.3V ± 10%, 4.0/2.2V@VDD:5V ± 10%
Two sets of pressure threshold detectors.
The pressure threshold detection range can be individually selected depending on the EEPROM
data.
• Pressure above a certain value is detected
• Pressure below a certain value is detected
The DET1 and DET2/PTH pins go high when the detected pressure exceeds the threshold (the
polarity change by EEPROM is possible). The detection threshold can be set by the input of
DET2/PTH pin (in this case, Pressure Threshold Detector 2 cannot use) or using the EEPROM
data. The hysteresis voltage can be adjusted at 2 bits, and it varies ratiometrically with
respect to the supply voltage as well as the detection threshold.
Note) The exact pressure determination cannot be achieved until the VOUT pin output is
stabilized after power-up.
MS1600-E-00
-8-
2014/05