AK8999AW Datasheet, PDF(33/68 Page) Asahi Kasei Microsystems

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AK8999AW Datasheet, PDF (33/68 Pages) Asahi Kasei Microsystems – Pressure Sensor Control IC

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CONFIDENTIAL

[AK8999A/AW/AD]

1.7) Offset Voltage Adjustment

The offset voltage for the pressure sensor is adjusted including the AK8999A internal error by using the

offset voltage adjustment EEPROM (address: 00h, 01h, data: EOCR[3:0], EOCF[7:0]).

â Offset Voltage Adjustment Example (@VDD:5V)

EOCR[3]: Offset voltage coarse adjustment sign bit

If unadjusted output is more than 0.5*VDD, set EOCR[3] = 1h.

If unadjusted output is less than 0.5*VDD, set EOCR[3] = 0h.

EOCR[2:0]: Offset voltage coarse adjustment: Adjust in 1600 mV steps.

EOCF[7]: Offset voltage fine adjustment sign bit

If unadjusted output is more than 0.5*VDD, set EOCF[7] = 1h.

If unadjusted output is less than 0.5*VDD, set EOCF[7] = 0h.

EOCF[6:0]: Offset voltage fine adjustment: Adjust in 8 mV steps.

When the offset voltage is +360mV (0.5*VDD reference), set EOCF[7] = 1h and

EOCF[6:0] = 45dec.

360[mV]-(8[mV]*45[dec]) = 0.0[mV]

1.8) Output Reference Voltage Adjustment

Adjust the output reference voltage. The output reference voltage is adjusted by using the output

reference voltage adjustment EEPROM (address: 03h, 08h, data: ELV[8], ELV[7:0]).

â Output Reference Voltage Adjustment Example (@VDD:5V)

When the output reference voltage is 100mV, set ELV[8] = 0h and ELV[7:0] = 240dec.

2500[mV]+(-0.002*240[dec])*5000[mV] = 100[mV]

1.9) Output Span Voltage Adjustment

The output span voltage for the connected pressure sensor is adjusted, including the AK8999A internal

error, by using the output span voltage adjustment EEPROM. (address: 00h, 02h, data: ESCR[0],

ESC[7:0])

In the case, the output span voltage cannot be adjusted to the target span voltage by the max code

(ESC[7:0] = FFh), please raise 1 code at G1 gain and readjust 1.7) Offset Voltage Adjustments.

â Output Span Voltage Adjustment Example (@VDD:5V)

When the output is 3700mV, set ESCR[0] = 1, ESC[7:0] = 153dec (target span voltage

4800mV).

(3700[mV]-100[mV])*1.8*(1-0.2*153/275)/(1+0.2*153/152.86) = 4800[mV]

MS1600-E-00

- 33 -

2014/05

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