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AsahiKASEI AK8975 Manual

3-axis electronic compass
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A 3-axis electronic compass IC with high sensitive Hall sensor technology.
Best adapted to pedestrian city navigation use for cell phone and other portable appliance.
Functions:
• 3-axis magnetometer device suitable for compass application
• Built-in A to D Converter for magnetometer data out
• 13 bit data out for each 3 axis magnetic components
- Sensitivity: 0.3 µT / LSB typ.
• Serial interface
2
- I
C bus interface.
Standard mode and Fast mode compliant with Philips I
- 4-wire SPI
• Operation mode:
Power-down mode, Single Measurement mode, Self test mode and Fuse access mode.
• 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 built-in internal magnetic source
Operating temperatures:
•
Operating supply voltage:
• Analog power supply
• Digital Interface supply
Current consumption:
• Power-down:
• Measurement:
- Average power consumption at 8 Hz repetition rate: 350 µA typ.
Package:
AK8975
16-pin QFN package:
AK8975C 14-pin WL-CSP (BGA):
MS1187-E-02
AK8975/AK8975C
3-axis Electronic Compass
1.
1.

Features

Features
-30°C to +85°C
+2.4V to +3.6V
+1.65V to analog power supply voltage.
10 µA max.
4.0 mm × 4.0 mm × 0.75 mm
2.0 mm × 2.0 mm × 0.6 mm
- 1 -
2
C specification Ver.2.1
[AK8975/C]
2010/05

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Summary of Contents for AsahiKASEI AK8975

  • Page 1: Features

    [AK8975/C] AK8975/AK8975C 3-axis Electronic Compass Features Features A 3-axis electronic compass IC with high sensitive Hall sensor technology. Best adapted to pedestrian city navigation use for cell phone and other portable appliance. Functions: • 3-axis magnetometer device suitable for compass application •...

  • Page 2: Overview

    Average power consumption at 8Hz repetition rate: 350 µA typ. (3) Digital serial interface C bus interface to control AK8975/C functions and to read out the measured data by external CPU. A dedicated power supply for I C bus interface can work in low-voltage apply as low as 1.65V.

  • Page 3: Table Of Contents

    [AK8975/C] Table of Contents Features ............................1 Overview ...........................2 Table of Contents ........................3 Circuit Configuration ........................5 4.1. Block Diagram ........................5 4.2. Block Function........................5 4.3. Pin Function ........................6 Overall Characteristics ......................7 5.1. Absolute Maximum Ratings....................7 5.2. Recommended Operating Conditions ................7 5.3. Electrical Characteristics ....................7 5.3.1.
  • Page 4 [AK8975/C] Example of Recommended External Connection ..............29 9.1. C Bus Interface ......................29 9.2. 4-wire SPI.........................30 10. Package ..........................31 10.1. Marking ..........................31 10.2. Pin Assignment ........................31 10.3. Outline Dimensions ......................32 10.4. Recommended Foot Print Pattern ..................33 11. Relationship between the Magnetic Field and Output Code............34...

  • Page 5: Circuit Configuration

    [AK8975/C] Circuit Configuration 4.1. Block Diagram 3-axis Chopper Pre- Hall Integrator＆ADC sensor OSC1 HE-Drive SCL/SK Interface, Logic SDA/SI & Register Timing Control Magnetic source Voltage Reference DRDY FUSE ROM CAD1 CAD0 TST1 TST2 TST6 4.2. Block Function Block Function 3-axis Hall sensor Monolithic Hall elements.

  • Page 6: Pin Function

    [AK8975/C] 4.3. Pin Function Pin No. Power Type Function supply name system Test pin. TST1 ANALOG Hi-Z output. Keep this pin electrically nonconnected. Chip select pin for 4-wire SPI. CMOS “L” active. Connect to VID when selecting I C bus interface.

  • Page 7: Overall Characteristics

    [AK8975/C] Overall Characteristics 5.1. Absolute Maximum Ratings Vss=0V Parameter Symbol Min. Max. Unit -0.3 +6.5 Power supply voltage (Vdd, Vid) -0.3 (V+)+0.3 Input voltage ± 10 Input current +125 °C Storage temperature (Note 1) If the device is used in conditions exceeding these values, the device may be destroyed. Normal operations are not guaranteed in such exceeding conditions.

  • Page 8: Ac Characteristics

    Wait time before mode Twat μ s setting (Note 7) Reference value for design (Note 8) Only when VDD meets this condition, POR circuit starts and resets AK8975/C. After reset, all registers are initialized and AK8975/C transits to Power-down mode. tPUP 90%Vdd 10%Vdd 5.3.3.

  • Page 9: 4-Wire Spi

    [AK8975/C] 5.3.4. 4-wire SPI 4-wire SPI is compliant with mode 3 Parameter Symbol Condition Min. Typ. Max. Unit CSB setup time Data setup time Data hold time SK high time Vid≥2.5V 2.5V>Vid≥1.65V SK low time Vid≥2.5V 2.5V>Vid≥1.65V SK setup time...

  • Page 10: I 2 C Bus Interface

    [AK8975/C] 5.3.5. I C Bus Interface CSB pin = “H” C bus interface is compliant with Standard mode and Fast mode. Standard/Fast mode is selected automatically by fSCL. (1) Standard mode fSCL≤100kHz 1.65V≤Vid≤Vdd Symbol Parameter Min. Typ. Max. Unit fSCL...

  • Page 11: Functional Explanation

    6.1. Power States When VDD and VID are turned on from Vdd=OFF (0V) and Vid=OFF (0V), all registers in AK8975/C are initialized by POR circuit and AK8975/C transits to Power-down mode. All the states in the table below can be set, although the transition from state 2 to state 3 and the transition from state 3 to state 2 are prohibited.

  • Page 12: Operation Modes

    MODE[3:0]=“0000”. Figure 6.1 Operation modes When power is turned ON, AK8975/C is in power-down mode. When MODE[3:0] is set, AK8975/C transits to the specified mode and starts operation. When user wants to change operation mode, transit to power-down mode first and then transit to other modes. After power-down mode is set, at least 100μs(Twat) is needed before setting another mode.

  • Page 13: Description Of Each Operation Mode

    “Data Ready”. DRDY pin is in the same state as DRDY bit. When measurement is performed correctly, AK8975/C becomes Data Ready on transition to Power-down mode (PD) after measurement. The period from the end of Nth measurement to the start of (N+1)th measurement is called “Data Readable Period”. Stored measurement data should be read during Data Readable Period.

  • Page 14: Data Error

    Register Figure 6.4 Data Error 6.4.2.3. Magnetic Sensor Overflow AK8975/C has the limitation for measurement range that the sum of absolute values of each axis should be smaller than 2400μT. |X|+|Y|+|Z| < 2400μT When the magnetic field exceeded this limitation, data stored at measurement data are not correct. This is called Magnetic Sensor Overflow.

  • Page 15: Self-Test Mode

    (5) Read measurement data (HXL to HZH) (6) Write “0” to SELF bit of ASTC register <Self-test Judgement> When measurement data read by the above sequence is in the range of following table after sensitivity adjustment (refer to 8.3.11), AK8975/C is working normally. HX[15:0] HY[15:0] HZ[15:0] Criteria -100≤X≤+100...

  • Page 16: Serial Interface

    8 bits specify the R/W control bit (R/W=“0” when writing) and register address (7bits), and the latter 8 bits are control data (8bits). When any of addresses listed on Table 8.1 is input, AK8975/C recognizes that it is selected and takes in latter 8 bits as setting data.

  • Page 17: Reading Data

    Input the R/W control bit (R/W=“1”) and 7 bit register address on SI pin in synchronous with the first 8 bits of the 16 bits of a serial clock input on SK pin. Then AK8975/C outputs the data held in the specified register with MSB first from SO pin.

  • Page 18: I 2 C Bus Interface

    [AK8975/C] 7.2. C Bus Interface The I C bus interface of AK8975/C supports the standard mode (100 kHz max.) and the fast mode (400 kHz max.). 7.2.1. Data Transfer To access AK8975/C on the bus, generate a start condition first.

  • Page 19: Acknowledge

    7.2.1.4. Slave Address The slave address of AK8975/C can be selected from the following list by setting CAD0/1 pin. When CAD pin is fixed to VSS, the corresponding slave address bit is “0”. When CAD pin is fixed to VDD, the corresponding slave address bit is “1”.

  • Page 20: Write Instruction

    When the R/W bit is set to "0", AK8975/C performs write operation. In write operation, AK8975/C 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.

  • Page 21: Read Instruction

    When the R/W bit is set to "1", AK8975/C performs read operation. If a master IC generates an acknowledge instead of a stop condition after AK8975/C transfers the data at a specified address, the data at the next address can be read.

  • Page 22: Registers

    Registers 8.1. Description of Registers AK8975/C has registers of 19 addresses as indicated in Table 8.1. Every address consists of 8 bits data. Data is transferred to or received from the external CPU via the serial interface described previously. READ/...

  • Page 23: Register Map

    COEFZ2 COEFZ1 COEFZ0 Table 8.2 Register Map When VDD is turned ON, POR function works and all registers of AK8975/C are initialized regardless of VID status. To write data to or to read data from register, VID must be ON.

  • Page 24: Detailed Description Of Registers

    [AK8975/C] 8.3. Detailed Description of Registers 8.3.1. WIA: Device ID Register Addr name Read-only register Device ID of AKM. It is described in one byte and fixed value. 48H: fixed 8.3.2. INFO: Information Register Addr name Read-only register INFO INFO7...

  • Page 25: Hxl To Hzh: Measurement Data

    [AK8975/C] 8.3.4. HXL to HZH: Measurement Data Addr Register name Read-only register HX15 HX14 HX13 HX12 HX11 HX10 HY15 HY14 HY13 HY12 HY11 HY10 HZ15 HZ14 HZ13 HZ12 HZ11 HZ10 Reset Measurement data of magnetic sensor X-axis/Y-axis/Z-axis HXL[7:0]: X-axis measurement data lower 8bit...

  • Page 26: St2: Status 2

    "1111": Fuse ROM access mode Other code settings are prohibited When each mode is set, AK8975/C transits to set mode. Refer to 6.3 for detailed information. When CNTL register is accessed to be written, registers from 02H to 09H are initialized.

  • Page 27: Rsv: Reserved

    Once I2CDIS is turned to “1” and I C bus interface is disabled, re-setting I2CDIST to “0” is prohibited. To enable I C bus interface, reset AK8975/C by turning VDD or VID to OFF (0V) once. - 27 - 2010/05...

  • Page 28: Asax, Asay, Asaz: Sensitivity Adjustment Values

    [AK8975/C] 8.3.11. ASAX, ASAY, ASAZ: Sensitivity Adjustment values Register Addr name Read-only register ASAX COEFX7 COEFX6 COEFX5 COEFX4 COEFX3 COEFX2 COEFX1 COEFX0 ASAY COEFY7 COEFY6 COEFY5 COEFY4 COEFY3 COEFY2 COEFY1 COEFY0 ASAZ COEFZ7 COEFZ6 COEFZ5 COEFZ4 COEFZ3 COEFZ2 COEFZ1 COEFZ0 Reset Sensitivity adjustment data for each axis is stored to fuse ROM on shipment.

  • Page 29: Example Of Recommended External Connection

    0 0 0 1 1 1 0 R/W Host CPU 0 0 0 1 1 1 1 R/W Interrupt CAD0 open AK8975 open TST2 (Top View) open SDA/SI C i/f 0.1µF open or 0.1µF Power for i/f <AK8975C> Same as AK8975 - 29 - 2010/05 MS1187-E-02...

  • Page 30: 4-Wire Spi

    [AK8975/C] 9.2. 4-wire SPI <AK8975> POWER 2.4V~3.6V POWER 1.65V~Vdd Host CPU Interrupt CAD0 open AK8975 open TST2 (Top View) SDA/SI 4-wireSPI i/f 0.1µF 0.1µF Power for i/f open or <AK8975C> Same as AK8975 - 30 - 2010/05 MS1187-E-02...

  • Page 31: Package

    [AK8975/C] Package 10.1. Marking <AK8975> <AK8975C> • Company logo: AKM • Product name: 8975C • Product name: • Date code: 8975 • Date code: = ID = Year code = ID = Week code = Year code = Lot = Week code...

  • Page 32: Outline Dimensions

    [AK8975/C] 10.3. Outline Dimensions <AK8975> [mm] 4.00±0.10 2.6± 0.10 0.30 REF. 8975 XXXXX C0.30. 0.40±0.10 0.65 REF. 0.30±0.05 0.10 M C A B 0.75±0.05 0.08 C <AK8975C> [mm] 1.96 8975C XXXXX 0.27±0.03 0.40 0.65 max. 0.19 0.075 C - 32 -...

  • Page 33: Recommended Foot Print Pattern

    [AK8975/C] 10.4. Recommended Foot Print Pattern <AK8975> [mm] <AK8975C> [mm] 0.25 - 33 - 2010/05 MS1187-E-02...

  • Page 34: Relationship Between The Magnetic Field And Output Code

    [AK8975/C] Relationship between the Magnetic Field and Output Code The measurement data increases as the magnetic flux density increases in the arrow directions. <AK8975> <AK8975C> Important Notice • These products and their specifications are subject to change without notice. When you consider any use or application of these products, please make inquiries the sales office of Asahi Kasei Microdevices Corporation (AKM) or authorized distributors as to current status of the products.

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