AK8996 Datasheet, PDF (31/74 Pages) Asahi Kasei Microsystems – Pressure Sensor Interface IC

[AK8996/W]
Functional Description
1) Adjustment Procedure Description (Example)
The adjustment procedure for the AK8996 follows (See "Adjustment Sequence.").
Note) When shipped in package form, the adjustments for the items 1-4 below have been completed. It is
necessary to read the data (items 1-4 below) from a chip first and after initializing the EEPROM,
rewrite the readout data. Note that depending on the required accuracy and implementation status,
there could be some cases where items 1-4 should be readjusted. The factory default adjustment is
with reference to 5V mode (EVD[0]=0).If 3V mode (EVD[0]=1) is used, readjustment is required.
The EEPROM register address is referred to as "address," while the control register (volatile memory)
address is referred to as "C address."
1. VREF Adjustment (completed when shipped in package form)
The reference voltage is adjusted to 1.0V. Adjusting the VREF voltage also means adjustment of the
sensor drive voltage (VS).
Configuring the adjustment mode 1 register (C address: 00h data AM[3:0]:1h) allows the VREF
voltage to be output at the DET pin (See recommended connection examples for components).
2. IREF Adjustment (completed when shipped in package form)
The reference current is adjusted to 20.0µA.
Configuring the adjustment mode 1 register (C address: 00h data AM[3:0]:2h) allows the IREF voltage
to be output at the DET pin (See recommended connection examples for components).
3. OSC Adjustment (completed when shipped in package form)
The intermittent operation control clock is adjusted to 1024kHz.
Configuring the adjustment mode 1 register (C address: 00h data AM[3:0]:3h) allows the OSC output
to be output at the DET pin (See recommended connection examples for components).
4. VTMP Adjustment (completed when shipped in package form)
Temperature sensor output (VTMP) voltage is adjusted to match the VREF voltage.
Configuring the adjustment mode 1 register (C address: 00h data AM[3:0]:4h) allows the VTMP
voltage to be output at the DET pin (See recommended connection examples for components).
Since a quadratic function generator is used to compensate for the sensor characteristics, the VTMP
output should be matched with the VREF voltage.
5. Offset Voltage Adjustment
The offset voltage for the pressure sensor is adjusted, including the AK8996 internal error.
The offset voltage is adjusted using the offset voltage rough adjustment register (Address: 00h data
EOC[10:7]) and offset voltage fine adjustment register (Address: 01h data EOC[6:0]).
Since the offset voltage temperature drift is to be compensated for afterwards, the complete
adjustment cannot be performed. Final readjustment is required including the level shift voltage error
(See Section 11).
MS1055-E-02
31
2011/12