AK8998 Datasheet, PDF (9/59 Pages) Asahi Kasei Microsystems – Preliminary

[AK8998/W/D]
Reference Section & Others
Block
Functions
Generates the reference voltage or bias current required for each circuit.
V_Bandgap Adjust the VREF voltage so that it is equivalent to 1.0V.
(VBG)
VREF voltage adj.
Resolution 3bits
V_Reference
Adj. step
1% / step
(VREF) IREF current should be adjusted to 1.0V voltage across 1MΩ external resistor tied
I_Reference to VOUT pin.
(IREF)
IREF current adj.
Resolution 4bits
Adj. step
2.8% / step
Oscillator to generate timing sync signals for internal operation and sampling
frequencies for sensor output signals. Oscillation frequency is adjusted as the
Oscillator
(OSC)
counter result reaches the expected value, the internal counter counts for the
period of CSCLK is high (2msec typ.). For the detail, refer to the Functional
Description 1) Adjustment Procedure Description (Example).
OSC adj.
Resolution 4bits
Adj. step
5% / step
Temperature sensor for converting the ambient temperature to voltage. Adjust the
temperature sensor output voltage (VTMP voltage) so that it is equivalent to VREF
voltage at 25ºC.
V_temp.
(VTMP)
And it is also possible to select the external temperature sensor by EEPROM in
consideration of the case where a pressure sensor and the AK8998 are separated
physically. When the external temperature sensor is chosen, the constant current
of 50µA is sinked from the EXTMP pin to VSS.
VTMP voltage adj.(internal) Resolution 6bits
Adj. step 0.2% / step
VTMP voltage adj.(external) Resolution 9bits (Rough/Fine=3/6bits)
Adj. step Rough 10% /step / Fine 0.2% /step
Generates analog circuit reference voltage 1/2VDD.
The internal power-up circuit causes it to start up within the settling time for stable
V_Common analog operation (Start Up valid time). AGND pin can be validated by EEPROM
(VCOM) (EAGND[0]=1h). It is effective to improve the noise characteristic (See
recommended connection examples for components). In the case of EAGND[0]=0h,
the AGND pin is Hi-Z.
Power ON
Reset(POR)
Power Up circuit is for stable analog operation upon power-up.
In order to make the power-on reset effective, be sure to power up the supply
voltage from below 0.1*VDD.
Serial I/F
Serial interface for accessing EEPROM and control register (volatile memory). It
accesses using the CSCLK pin and the VOUT pin.
EEPROM & EEPROM and control register (volatile memory).
Control
Register
Used to store compensation values and measurement modes and to set up the
measurement modes for adjustment.
MSxxxxx-E-00
-9-
2012/11