AK8999A Datasheet, PDF (35/68 Pages) Asahi Kasei Microsystems – Pressure Sensor Control IC

CONFIDENTIAL
[AK8999A/AW/AD]
1.11) Sensitivity Temperature Drift Adjustment
The sensitivity temperature drift for the pressure sensor is adjusted, including the AK8999A internal
error, by using the sensitivity temperature drift adjustment EEPROM (address: 03h, 05h, 06h, data:
ESTP/N[8], ESTP/N[7:0]).
■Sensitivity Temperature Drift Adjustment Example (@VDD:5V, ESTC[0] = 1h)
Adjusting the low and high temperature coefficient is explained separately.
When this function is not used, set the same data as ESTP[8:0] and ESTN[8:0].
 Adjusting the high temperature coefficient
ESTP[8]: Sensitivity temperature drift adjustment sign bit (target span voltage 4800mV)
If unadjusted output is greater than 4800mV (with respect to the output reference voltage) at
Ta = 105C, set ESTP[8] = 0h.
If unadjusted output is smaller than 4800mV (with respect to the output reference voltage) at
Ta = 105C, set ESTP[8] = 1h.
ESTP[7:0]: Sensitivity temperature drift adjustment: Adjust in -18ppm/C steps.
If the output voltage is +4,400mV (with respect to the output reference voltage e.g.100mV) at
Ta = 105C, set ESTP[8] = 1h, EST[7:0] = 58dec.
4400[mV]-(105[C]-25[C])*(-18[ppm/C]*58[dec])*4800[mV] = 4800.9[mV]
 Adjusting the high temperature coefficient
ESTN[8]: Sensitivity temperature drift adjustment sign bit (target span voltage 4800mV)
If unadjusted output is greater than 4800mV (with respect to the output reference voltage) at
Ta = -40C, set ESTN[8] = 1h.
If unadjusted output is smaller than 4800mV (with respect to the output reference voltage) at
Ta = -40C, set ESTN[8] = 0h.
ESTN[7:0]: Sensitivity temperature drift adjustment: Adjust in 18ppm/C steps.
If the output voltage is +4,400mV (with respect to the output reference voltage e.g.100mV) at
Ta = -40C, set ESTN[8] = 0h, ESTN[7:0] = 71dec.
4400[mV]-(-40[C]-25[C])*(18[ppm/C]*71[dec])*4800[mV] = 4798.7[mV]
1.12) Offset Voltage Fine Adjustment
The offset voltage error is caused by compensating the offset voltage temperature drift. The offset
voltage is adjusted using the offset voltage fine adjustment EEPROM (Address: 01h, data: EOCF[6:0]).
Note) Can not chage the polarity of EOCF[7] bit at this adjustment process, because the polarity of an
offset temperature coefficient changes with chaging the polarity of EOCF[7] bit.
1.13) Output Span Voltage Fine Adjustment
The output span voltage error is caused by compensating the span voltage temperature drift. The output
span voltage is adjusted using the output span voltage adjustment EEPROM (Address: 02h, data:
ESC[7:0]).
MS1600-E-00
- 35 -
2014/05