AK9720 Datasheet, PDF (16/31 Pages) Asahi Kasei Microsystems – IR Sensor Module with I2C I/F

[AK9720]
4. Explanation for Each Operating Mode
4.1 Power down Mode (MODE [2:0] =”000”)
Power supply to most internal circuits is turned off. All registers can be accessed in Power
down Mode. Read/Write register data are retained, and reset by software reset. However,
EEPROM data cannot be read. Reading EEPROM data must be done in EEPROM Access
Mode.
4.2 EEPROM Access Mode (MODE [2:0] =”100”)
When MODE [2:0] is changed from Power down Mode (MODE [2:0] =”000”) to MODE
[2:0]=”100” , the AK9720 shifts to EEPROM Access Mode. Reading EEPROM data should
be done in EEPROM Access Mode. Measurement is not done in EEPROM Access Mode.
4.3 Single shot Mode (MODE [2:0] =”001”)
When AK9720 is set to Single shot Mode (MODE [2:0] =”001”), a measurement and
signal processing are done, then the measurement data (IRSL to TMPH data) are stored to
the measurement data registers, and the AK9720 shifts to Power down Mode automatically.
When the AK9720 shifts to Power down Mode, MODE [2:0] changes to ”000”.
Simultaneously, the DRDY bit of ST1 register changes to “1”. This is called “Data Ready”.
If either the measurement data register (IRSL to TMPH) or ST2 register is read out in “data
ready” state, the DRDY bit changes to “0”. When the AK9720 shifts from Power down
Mode to other modes, the DRDY bit retains “1”.
Measurement data register retains previous data, within the measurement period.
Measurement data can be read out in the measurement period. When measurement data
is read out in a measurement period, the previous data retained is read out.
Operating mode_：
Power down
Single Measurement
(1)
Measurement Period
Measurement data register
data(1)
(2)
(3)
data(2)
data(3)
DRDY
Read-out data
data(1)
ST1
ST2
data(3)
ST1
Register Write MODE[2:0]="001"
MODE[2:0]="001"
MODE[2:0]="001"
Fig.2. Single shot Mode (when measurement data is read, out of the measurement period.)
Rev.02
AKM Confidential
- 16 -
2012/11