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[AK09918]

016014242-E-00 2016/11

- 1 -

1. General Description

AK09918 is 3-axis electronic compass IC with high sensitive Hall sensor technology.

Small package of AK09918 incorporates magnetic sensors for detecting terrestrial magnetism in the X-axis,

Y-axis, and Z-axis, a sensor driving circuit, signal amplifier chain, and an arithmetic circuit for processing

the signal from each sensor. Self-test function is also incorporated. From its compact foot print and thin

package feature, it is suitable for map heading up purpose in Smart phone to realize pedestrian navigation

function.

2. Features

 Functions:

 3-axis magnetometer device suitable for compass application

 Built-in A to D Converter for magnetometer data out

 16-bit data out for each 3-axis magnetic component

 Sensitivity: 0.15 µT/LSB (typ.)

 Serial interface

 I

C bus interface

Standard and Fast modes compliant with Philips I

C specification Ver.2.1

 Operation mode

 Power-down, Single measurement, Continuous measurement and Self-test

 DRDY function for measurement data ready

 Magnetic sensor overflow monitor function

 Built-in oscillator for internal clock source

 Power on Reset circuit

 Self-test function with internal magnetic source

 Built-in magnetic sensitivity adjustment circuit

 Operating temperatures:

 -30˚C to +85˚C

 Operating supply voltage:

 +1.65V to +1.95V

 Current consumption:

 Power-down: 1 µA (typ.)

 Measurement:

 Average current consumption at 100 Hz repetition rate: 1.1mA (typ.)

 Package:

 AK09918C 4-pin WL-CSP (BGA): 0.8 mm  0.8 mm  0.5mm

AK09918

3-axis Electronic Compass

Summary of content (30 pages)

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[AK09918] AK09918 3-axis Electronic Compass 1. General Description AK09918 is 3-axis electronic compass IC with high sensitive Hall sensor technology. Small package of AK09918 incorporates magnetic sensors for detecting terrestrial magnetism in the X-axis, Y-axis, and Z-axis, a sensor driving circuit, signal amplifier chain, and an arithmetic circuit for processing the signal from each sensor. Self-test function is also incorporated.
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[AK09918] 3. Table of Contents 1. General Description .................................................................................................................. 1 2. Features ..................................................................................................................................... 1 3. Table of Contents ...................................................................................................................... 2 4. Block Diagram and Functions ...................
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[AK09918] 4. Block Diagram and Functions 3-axis Hall sensor Chopper SW PreAMP Integrator＆ADC MUX OSC HE-Drive SCL Timing Control VREF Interface Logic & Register SDA Magnetic source POR VSS Block 3-axis Hall sensor MUX Chopper SW HE-Drive Pre-AMP Integrator & ADC OSC POR VREF Interface Logic & Register Timing Control Magnetic Source VDD Function Monolithic Hall elements. Multiplexer for selecting Hall elements. Performs chopping. Magnetic sensor drive circuit.
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[AK09918] 5. Pin Configurations and Functions Pin No. A1 Pin name VSS I/O - Type - A2 SCL I CMOS B1 VDD - Power B2 SDA I/O CMOS Function Ground pin. Control data clock input pin. Input: Schmidt trigger Positive power supply pin. Control data input/output pin. Input: Schmidt trigger, Output: Open-drain 6.
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[AK09918] 8. Electrical Characteristics The following conditions apply unless otherwise noted: Vdd = 1.65V to 1.95V, Temperature range = -30˚C to +85˚C. 8.1. DC Characteristics Parameter High level input voltage Symbol VIH Low level input voltage VIL Input current IIN Hysteresis input voltage (Note 1) VHS SCL SDA Low level output voltage (Note 2) VOL SDA IOL ≤ +3mA Current consumption (Note 3) IDD1 VDD Power-down mode Vdd = 1.
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[AK09918] 8.2. AC Characteristics Parameter Power supply rise time (Note 4) POR completion time (Note 4) Power supply turn off voltage (Note 4) Power supply turn on interval (Note 4) Symbol PSUP Wait time before mode setting Twait (Note 4) (Note 5) Pin VDD PORT SDV VDD PSINT VDD Condition Period of time that VDD changes from 0.2V to Vdd.
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[AK09918] 8.4. I2C Bus Interface I2C bus interface is compliant with Standard mode and Fast mode. Standard/Fast mode is selected automatically by fSCL.  Standard mode fSCL ≤ 100kHz Symbol fSCL tHIGH tLOW tR tF tHD:STA tSU:STA tHD:DAT tSU:DAT tSU:STO tBUF  Parameter SCL clock frequency SCL clock “High” time SCL clock “Low” time SDA and SCL rise time SDA and SCL fall time Start Condition hold time Start Condition setup time SDA hold time (vs. SCL falling edge) SDA setup time (vs.
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[AK09918] 9. Function Descriptions 9.1. Power States When VDD is turned on from Vdd = OFF (0V), all registers in AK09918 are initialized by POR circuit and AK09918 transits to Power-down mode. Table 9.1. Power state State 1 VDD OFF (0V) 2 1.65V to 1.95V Power state OFF It doesn’t affect external interface. ON 9.2. Reset Functions Power on Reset (POR) works until Vdd reaches to the operation effective voltage (about 1.1V: reference value for design) on power-on sequence.
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[AK09918] 9.3. Operation Modes AK09918 has following seven operation modes: (1) Power-down mode (2) Single measurement mode (3) Continuous measurement mode 1 (4) Continuous measurement mode 2 (5) Continuous measurement mode 3 (6) Continuous measurement mode 4 (7) Self-test mode By setting CNTL2 register MODE[4:0] bits, the operation set for each mode is started. A transition from one mode to another is shown below.
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[AK09918] 9.4. Description of Each Operation Mode 9.4.1. Power-down Mode Power to almost all internal circuits is turned off. All registers are accessible in Power-down mode. Data stored in read/write registers are remained. They can be reset by soft reset. 9.4.2. Single Measurement Mode When Single measurement mode (MODE[4:0] bits = “00001”) is set, magnetic sensor measurement is started.
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[AK09918] 9.4.3. Continuous Measurement Mode 1, 2, 3 and 4 When Continuous measurement mode 1 (MODE[4:0] bits = “00010”), 2 (MODE[4:0] bits = “00100”), 3 (MODE[4:0] bits = “00110”) or 4 (MODE[4:0] bits = “01000”) is set, magnetic sensor measurement is started periodically at 10 Hz, 20 Hz, 50 Hz or 100 Hz respectively.
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[AK09918] 9.4.3.2. Normal Read Sequence (1) Check Data Ready or not by polling DRDY bit of ST1 register  DRDY: Shows Data Ready or not. Not when “0”, Data Ready when “1”.  DOR: Shows if any data has been skipped before the current data or not. There are no skipped data when “0”, there are skipped data when “1”. (2) Read measurement data When any of measurement data register (HXL to TMPS) or ST2 register is read, AK09918 judges that data reading is started.
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[AK09918] 9.4.3.4. Data Skip When Nth data was not read before (N+1)th measurement ends, Data Ready remains until data is read. In this case, a set of measurement data is skipped so that DOR bit turns to “1”. When data reading started after Nth measurement ended and did not finish reading before (N+1)th measurement ended, Nth measurement data is protected to keep correct data. In this case, a set of measurement data is skipped and not stored so that DOR bit turns to “1”.
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[AK09918] Although Nth data is read out when it is performed during (N+1)th measurement period, (N+1)th data is obtained by reading out again before completion of (N+2)th measurement. (N-1)th PD Nth (N+1)th PD Measurement Internal Buffer (N-1)th Nth Measurement Data Register (N-1)th (N+2)th PD Measurement PD Measurement (N+1)th (N+2)th Nth (N+1)th Data register is protected because data is being read DRDY changes to "1" because read-out becomes possible.
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[AK09918] 9.4.4. Self-test Mode Self-test mode is used to check if the magnetic sensor is working normally. When Self-test mode (MODE[4:0] bits = “10000”) is set, magnetic field is generated by the internal magnetic source and magnetic sensor is measured. Measurement data is stored to measurement data registers (HXL to HZH), then AK09918 transits to Power-down mode automatically. Data read sequence and functions of read-only registers in Self-test mode is the same as Single measurement mode. 9.4.4.1.
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[AK09918] 10. Serial Interface 10.1. I2C Bus Interface The I2C bus interface of AK09918 supports the Standard mode (100 kHz max.) and the Fast mode (400 kHz max.). 10.1.1. Data Transfer To access AK09918 on the bus, generate a start condition first. Next, transmit a one-byte slave address including a device address. At this time, AK09918 compares the slave address with its own address. If these addresses match, AK09918 generates an acknowledgement, and then executes READ or WRITE instruction.
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[AK09918] 10.1.1.3. Acknowledge The IC that is transmitting data releases the SDA line (in the “High” state) after sending 1-byte data. The IC that receives the data drives the SDA line to “Low” on the next clock pulse. This operation is referred as acknowledge. With this operation, whether data has been transferred successfully can be checked. AK09918 generates an acknowledge after reception of a start condition and slave address.
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[AK09918] 10.1.2. WRITE Instruction When the R/W bit is set to “0”, AK09918 performs write operation. In write operation, AK09918 generates an acknowledge after receiving a start condition and the first byte (slave address) then receives the second byte. The second byte is used to specify the address of an internal control register and is based on the MSB-first configuration. MSB A7 LSB A6 A5 A4 A3 A2 A1 A0 Figure 10.5.
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[AK09918] 10.1.3. READ Instruction When the R/W bit is set to “1”, AK09918 performs read operation. If a master IC generates an acknowledge instead of a stop condition after AK09918 transfers the data at a specified address, the data at the next address can be read. Address can be 00h to 18h, 30h to 32h. When the address is 00h to 18h, the address is incremented 00h  01h  02h  03h  10h  11h ...  18h, and the address goes back to 00h after 18h.
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[AK09918] 11. Registers 11.1. Description of Registers AK09918 has registers of 18 addresses as indicated in Table 11.1. . Every address consists of 8 bits data. Data is transferred to or received from the external CPU via the serial interface described previously. Table 11.1.
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[AK09918] 11.2. Register Map Table 11.2. Register Map Addr.
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[AK09918] 11.3. Detailed Description of Register 11.3.1. WIA: Who I Am Addr. Register name D7 D6 00h 01h WIA1 WIA2 0 0 1 0 D5 D4 Read-only register 0 0 0 0 D3 D2 D1 D0 1 1 0 1 0 0 0 0 WIA1[7:0] bits: Company ID of AKM. It is described in one byte and fixed value. 48h: fixed WIA2[7:0] bits: Device ID of AK09918. It is described in one byte and fixed value. 0Ch: fixed 11.3.2. RSV: Reserved Addr.
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[AK09918] 11.3.4. HXL to HZH: Measurement Magnetic data Addr.
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[AK09918] 11.3.6. ST2: Status 2 Addr. 18h Register name ST2 Reset D7 D6 0 0 RSV31 0 D5 D4 Read-only register RSV30 RSV29 0 0 D3 D2 D1 D0 HOFL 0 RSV28 1 0 0 0 0 ST2[6:4] bits: Reserved register for AKM. HOFL: Magnetic sensor overflow “0”: Normal “1”: Magnetic sensor overflow occurred In Single measurement mode, Continuous measurement mode 1, 2, 3, 4, and Self-test mode, magnetic sensor may overflow even though measurement data register is not saturated.
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[AK09918] 11.3.9. CNTL3: Control 3 Addr. 32h Register name CNTL3 Reset D7 D6 0 0 0 0 D5 D4 Read/Write register 0 0 0 0 D3 D2 D1 D0 0 0 0 0 0 0 SRST 0 SRST: Soft reset “0”: Normal “1”: Reset When “1” is set, all registers are initialized. After reset, SRST bit turns to “0” automatically. 11.3.10. TS1, TS2: Test Addr. 33h 34h Register name TS1 TS2 Reset D7 0 D6 0 D5 D4 Read/Write register 0 0 D3 D2 D1 D0 0 0 0 0 TS1 and TS2 registers are AKM internal test register.
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[AK09918] 12. Example of Recommended External Connection VDD POWER 1.65V to 1.95V Host CPU Power for I/F B SDA VDD SCL VSS I2C I/F 0.
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[AK09918] 13. Package 13.1. Marking Date code:     X1X2 X3X4X5 X1 = ID X2 = Year code X3 =Month code X4X5 =Lot X1X2X3 X4X5 13.2.
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[AK09918] 13.3. Outline Dimensions [mm] 0.760.03 1 1 2 B B 0.4 0.760.03 2 0.4 A A +0.03 0.22-0.01 0.40 0.583 max. 0.147 0.03 C C 13.4. Recommended Foot Print Pattern [mm] 0.4 B 2 1 0.4 A 0.
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[AK09918] 14. Relationship between the Magnetic Field and Output Code The measurement data increases as the magnetic flux density increases in the arrow directions.
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[AK09918] IMPORTANT NOTICE 0. Asahi Kasei Microdevices Corporation (“AKM”) reserves the right to make changes to the information contained in this document without notice. When you consider any use or application of AKM product stipulated in this document (“Product”), please make inquiries the sales office of AKM or authorized distributors as to current status of the Products. 1.