LIS302DL_07 STMICROELECTRONICS | Alldatasheet
Document overview
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Technical content
Datasheet sections
- 1 Block diagram and pin description
- 1.1 Block diagram
- 1.2 Pin description
- 2 Mechanical and electrical specifications
- 2.1 Mechanical characteristics
- 2.2 Electrical characteristics
- 2.3 Communication interface characteristics
- 2.3.1 SPI - Serial Peripheral Interface
- 2.3.2 I2C - inter IC control interface
- 2.4 Absolute maximum ratings
- 2.5 Terminology
- 2.5.1 Sensitivity
- 2.5.2 Zero-g level
- 2.5.3 Self test
- 2.5.4 Click and Double Click recognition
- 3 Functionality
- 3.1 Sensing element
- 3.2 IC interface
- 3.3 Factory calibration
- 4 Application hints
- 4.1 Soldering information
- 5 Digital interfaces
- 5.1 I2C serial interface
- 5.1.1 I2C operation
- 5.2 SPI bus interface
- 5.2.1 SPI Read
- 5.2.2 SPI Write
- 5.2.3 SPI Read in 3-wires mode
Datasheet sections
- 9 Package information
- 10 Revision history
3-axis - ±2g/±8g smart digital output “piccolo” accelerometer Feature ■ 2.16V to 3.6V supply voltage ■ 1.8V compatible IOs ■ <1mW power consumption ■ ± 2g / ± 8g dynamically selectable full-scale ■ I2C/SPI digital output interface ■ Programmable multiple interrupt generator ■ Click and double click recognition ■ Embedded high pass filter ■ Embedded self test ■ 10000g high shock survivability ■ ECOPACK® RoHS and “Green” compliant (see Section 9) Application ■ Free-Fall detection ■ Motion activated functions ■ Gaming and virtual reality input devices ■ Vibration monitoring and compensation
Description
The LIS302DL is an ultra compact low-power three axes linear accelerometer. It includes a sensing element and an IC interface able to provide the measured acceleration to the external world through I 2C/SPI serial interface. The sensing element, capable of detecting the acceleration, is manufactured using a dedicated process developed by ST to produce inertial sensors and actuators in silicon. The IC interface is manufactured using a CMOS process that allows to design a dedicated circuit which is trimmed to better match the sensing element characteristics. The LIS302DL has dynamically user selectable full scales of ±2g/±8g and it is capable of measuring accelerations with an output data rate of 100Hz or 400Hz. A self-test capability allows the user to check the functioning of the sensor in the final application. The device may be configured to generate inertial wake-up/free-fall interrupt signals when a programmable acceleration threshold is crossed at least in one of the three axes. Thresholds and timing of interrupt generators are programmable by the end user on the fly. The LIS302DL is available in plastic Thin Land Grid Array package (TLGA) and it is guaranteed to operate over an extended temperature range from -40°C to +85°C. LGA-14 (3x5x0.9mm) Table 1. Device summary
8.2 Mechanical characteristics derived from measurement in the -40°C to +85°C
1 Block diagram and pin description
1.1 Block diagram
Figure 1. Block diagram
1.2 Pin description
Figure 2. Pin connection
Table 2. Pin description
1 Vdd_IO Power supply for I/O pins
2 GND 0V supply
3 Reserved Connect to Vdd
4 GND 0V supply
5 GND 0V supply
6 Vdd Power supply
8 INT 1 Inertial interrupt 1
9 INT 2 Inertial interrupt 2
10 GND 0V supply
11 Reserved Connect to Gnd
12 SDO SPI Serial data output
14 SCL
2 Mechanical and electrical specifications
2.1 Mechanical characteristics
Table 3. Mechanical characteristics (1) (2)
- All the parameters are specified @ Vdd=2.5V, T = 25°C unless otherwise noted
- Typical specificat ions are not guaranteed
- Verified by wafer level test and measur ement of initial offset and sensitivity
- Typical zero-g level offset value after MSL3 preconditioning
- Offset can be eliminated by enabl ing the built-in high pass filter
- If STM bit is used values change in sign for all axes
- Output data reach 99% of final value after 3/OD R when enabling Self-Test mode due to device filtering
- ODR is output data rate. Refer to Table 4 for specifications
2.2 Electrical characteristics
Table 4. Electrical characteristics (1) (2)
- All the parameters are specified @ Vdd=2.5V, T= 25°C unless otherwise noted
- Typical specification are not guaranteed
- It is possible to remove Vdd maintaining Vdd_IO withou t blocking the communication busses, in this condition the
measurement chain is powered off.
- Time to obtain valid data after exiting Power-Down mode
2.3 Communication interface characteristics
2.3.1 SPI - Serial Peripheral Interface
Subject to general operating conditions for Vdd and top. Figure 3. SPI slave timing diagram (2)
- Values are guaranteed at 10MHz clock fr equency for SPI with both 4 and 3 wires, based on characterization results, not
- Measurement points are done at 0.2·Vdd_IO and 0.8·Vdd_IO, for both Input and Output port
- When no communication is on-going, data on CS, SPC, SDI and SDO are driven by internal pull-up resistors
Table 5. SPI slave timing values
2.3.2 I 2C - inter IC control interface
Subject to general operating conditions for Vdd and top. Table 6. I 2C slave timing values Figure 4. I 2C slave timing diagram (4)
- Data based on standard I 2C protocol requirement, not tested in production
- A device must internally provide an hold time of at least 3 00ns for the SDA signal (referred to VIHmin of the SCL signal) to
- Cb = total capacitance of one bus line, in pF
- Measurement points are done at 0.2·Vdd_IO and 0.8·Vdd_IO, for both port
2.4 Absolute maximum ratings
Table 7. Absolute maximum ratings
LIS302DL Mechanical and electrical specifications
2.5 Terminology
2.5.1 Sensitivity
Sensitivity describes the gain of the sensor and can be determined e.g. by applying 1g acceleration to it. As the sensor can measure DC accelerations this can be done easily by pointing the axis of interest towards the center of the Earth, noting the output value, rotating the sensor by 180 degrees (point to the sky) and noting the output value again. By doing so, ±1g acceleration is applied to the sensor. Subtracting the larger output value from the smaller one and dividing the result by 2 leads to the actual sensitivity of the sensor. This value changes very little over temperature and also very little over time. The Sensitivity Tolerance describes the range of Sensitivities of a large population of sensor.
2.5.2 Zero-g level
Zero-g level Offset (Off) describes the deviation of an actual output signal from the ideal output signal if there is no acceleration present. A sensor in a steady state on a horizontal surface will measure 0g in X axis and 0g in Y axis whereas the Z axis will measure 1g. The output is ideally in the middle of the dynamic range of the sensor (content of OUT registers 00h, data expressed as 2’s complement number). A deviation from ideal value in this case is called Zero-g offset. Offset is to some extent a result of stress to a precise MEMS sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive mechanical stress. Offset changes little over temperature, see “Zero-g level change vs. temperature”. The Zero-g level of an individual sensor is stable over lifetime. The Zero-g level tolerance describes the range of Zero-g levels of a population of sensors.
2.5.3 Self test
Self Test allows to check the sensor functionality without moving it. The Self Test function is off when the self-test bit of CTRL_REG1 (control register 1) is programmed to ‘0‘. When the self-test bit of ctrl_reg1 is programmed to ‘1‘ an actuation force is applied to the sensor, simulating a definite input acceleration. In this case the sensor outputs will exhibit a change in their DC levels which is related to the selected full scale through the device sensitivity. When Self Test is activated, the device output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor and by the electrostatic test-force. If the output signals change within the amplitude specified inside Table 3, than the sensor is working properly and the parameters of the interface chip are within the defined specification.
2.5.4 Click and Doub le Click recognition
The Click and Double Click recognition functions help to create man-machine interface with little software overload. The device can be configured to output an interrupt signal on dedicated pin when tapped in any direction. If the sensor is exposed to a single input stimulus it generates an interrupt request on inertial interrupt pin (INT1 and/or INT2). A more advanced feature allows to generate and interrupt request when a “double click” with programmable time between the two events enabling a “mouse button like” use. This function can be fully programmed by the user in terms of expected amplitude and timing of the stimuli.
3 Functionality
The LIS302DL is a ultracompact, low-power, digital output 3-axis linear accelerometer packaged in a LGA package. The complete device includes a sensing element and an IC interface able to take the information from the sensing element and to provide a signal to the external world through an I 2C/SPI serial interface.
3.1 Sensing element
A proprietary process is used to create a surface micro-machined accelerometer. The technology allows to carry out suspended silicon structures which are attached to the substrate in a few points called anchors and are free to move in the direction of the sensed acceleration. To be compatible with the traditional packaging techniques a cap is placed on top of the sensing element to avoid blocking the moving parts during the moulding phase of the plastic encapsulation. When an acceleration is applied to the sensor the proof mass displaces from its nominal position, causing an imbalance in the capacitive half-bridge. This imbalance is measured using charge integration in response to a voltage pulse applied to the sense capacitor. At steady state the nominal value of the capacitors are few pF and when an acceleration is applied the maximum variation of the capacitive load is in fF range.
3.2 IC interface
The complete measurement chain is composed by a low-noise capacitive amplifier which converts into an analog voltage the capacitive unbalancing of the MEMS sensor and by analog-to-digital converters. The acceleration data may be accessed through an I 2C/SPI interface thus making the device particularly suitable for direct interfacing with a microcontroller. The LIS302DL features a Data-Ready signal (RDY) which indicates when a new set of measured acceleration data is available thus simplifying data synchronization in the digital system that uses the device. The LIS302DL may also be configured to generate an inertial Wake-Up and Free-Fall interrupt signal accordingly to a programmed acceleration event along the enabled axes. Both Free-Fall and Wake-Up can be available simultaneously on two different pins.
3.3 Factory calibration
The IC interface is factory calibrated for sensitivity (So) and Zero-g level (Off). The trimming values are stored inside the device by a non volatile memory. Any time the device is turned on, the trimming parameters are downloaded into the registers to be used during the normal operation. This allows the user to use the device without further calibration.
4 Application hints
Figure 5. LIS302DL electrical connection placed as near as possible to the pin 6 of the device (common design practice). 2C/SPI interface.When using the I2C, CS must be tied high. completely programmed by the user though the I2C/SPI interface.
4.1 Soldering information
qualified for soldering heat resistance according to JEDEC J-STD-020C. Leave “Pin#1 indicator” unconnected during soldering.
5 Digital interfaces
line must be tied high (i.e connected to Vdd_IO).
5.1 I 2C serial interface
whose content can also be read back. The relevant I2C terminology is given in the table below. embedded inside the LIS302DL. When the bus is free both the lines are high. Table 8. Serial interface pin description Table 9. Serial interface pin description
5.1.1 I 2C operation
to allow multiple data read/write. the SAD+read/write bit pattern is composed, listing all the possible configurations. Table 10. SAD+read/write patterns Table 11. Transfer when master is writing one byte to slave Table 12. Transfer when Master is writing multiple bytes to slave
terminated by the generation of a STOP (SP) condition. address of first register to read.
5.2 SPI bus interface
The Serial Interface interacts with the outside world with 4 wires: CS, SPC, SDI and SDO. Figure 6. Read and write protocol Table 13. Transfer when master is receiving (reading) one byte of data from slave Table 14. Transfer when master is receiving (reading) Table 15. Multiple bytes of data from slave
falling edge of SPC and should be captured at the rising edge of SPC. from the device is read. In latter case, the chip will drive SDO at the start of bit 8. bit 1: MS bit. When 0, the address will remain unchanged in multiple read/write commands. When 1, the address will be auto incremented in multiple read/write commands. bit 2-7: address AD(5:0). This is the address field of the indexed register. is 1 the address used to read/write data is incremented at every block. The function and the behavior of SDI and SDO remain unchanged.
5.2.1 SPI Read
Figure 7. SPI Read protocol performed adding blocks of 8 clock pulses at the previous one. bit 0: READ bit. The value is 1. bit 2-7: address AD(5:0). This is the address field of the indexed register.
Figure 8. Multiple bytes SPI Read protocol (2 bytes example)
5.2.2 SPI Write
Figure 9. SPI Write protocol performed adding blocks of 8 clock pulses at the previous one. bit 0: WRITE bit. The value is 0. bit 2 -7: address AD(5:0). This is the address field of the indexed register.
Figure 10. Multiple bytes SPI Write protocol (2 bytes example)
5.2.3 SPI Read in 3-wires mode
Figure 11. SPI Read protocol in 3-wires mode bit 0: READ bit. The value is 1. bit 2-7: address AD(5:0). This is the address field of the indexed register. Multiple read command is also available in 3-wires mode.
6 Register mapping
Table 16. Register address map
cause permanent damages to the device. Table 16. Register address map (continued)
7 Register description
write the data through serial interface.
7.1 WHO_AM_I (0Fh)
Table 17. Register
7.2 CTRL_REG1 (20h)
Table 18. Register Table 19. Register description to “1” the selected data-rate will be set equal to 400Hz. to check the functionality of the whole measurement chain.
set to 1. The default value is 1. set to 1. The default value is 1. set to 1. The default value is 1.
7.3 CTRL_REG2 (21h)
Table 20. Register interface mode output data are sent to SDA_SDI pad. internal registers related to trimming functions to permit a good behavior of the device itself. process the BOOT bit is set again to ‘0’. HP_coeff[2:1]. These bits are used to configure high-pass filter cut-off frequency ft. Table 21. Register description
Table 22. High pass filter cut-off frequency configuration.
7.4 CTRL_REG3 [Interrupt CTRL register] (22h)
Table 23. Register Table 24. Register description Table 25. Truth table
7.5 HP_FILTER_RESET (23h)
high pass-filter. If the high pass filter is enabled all three axes are instantaneously set to 0g. This allows to overcome the settling time of the high pass filter. IHL Interrupt active high, low. Default value 0. PP_OD Push-pull/Open Drain selection on interrupt pad. Default value 0. Data Signal on Int2 pad control bits. Default value 000. Data Signal on Int1 pad control bits. Default value 000.
001 F F _ W U _ 1
010 F F _ W U _ 2
100 D a t a r e a d y
7.6 STATUS_REG (27h)
Table 26. Register Table 27. Register description
7.7 OUT_X (29h)
Table 28. Register
7.8 OUT_Y (2Bh)
Table 29. Register description
7.9 OUT_Z (2Dh)
Table 30. Register
7.10 FF_WU_CFG_1 (30h)
Table 31. Register Table 32. Register desccription
7.11 FF_WU_SRC_1 (31h)
Table 33. Register Free-fall and wake-up source register. Read only register.
7.12 FF_WU_THS_1 (32h)
Table 34. Register description Table 35. Register Table 36. Register description
7.13 FF_WU_DURATION_1 (33h)
7.14 FF_WU_CFG_2 (34h)
Table 37. Register Table 38. Register description Table 39. Register Table 40. Register description
7.15 FF_WU_SRC_2 (35h)
Free-fall and wake-up source register. Read only register.
7.16 FF_WU_THS_2 (36h)
7.17 FF_WU_DURATION_2 (37h)
Table 41. Register Table 42. Register description Table 43. Register Table 44. Register description Table 45. Register
function is blocked when LIR=1 in configuration register and the interrupt event is verified.
7.18 CLICK_CFG (38h)
7.19 CLICK_SRC (39h)
Table 46. Register description Table 47. Register Table 48. Register description Table 49. Truth table
01 S i n g l e
Table 50. Register
7.20 CLICK_THSY_X (3Bh)
7.21 CLICK_THSZ (3Ch)
7.22 CLICK_TimeLimit (3Dh)
Table 51. Register description Table 52. Register Table 53. Register description Table 54. Register Table 55. Register description Table 56. Register
7.23 CLICK_Latency (3Eh)
From 0 to 255 msec with step of 1 msec.
7.24 CLICK_Window (3Fh)
From 0 to 255 msec with step of 1 msec. Table 57. Register Table 58. Register
8 Typical performance characteristics
8.1 Mechanical characteristics at 25°C
Figure 12. X axis 0-g level at 2.5V Figure 13. X axis sensitivity at 2.5V Figure 14. Y axis 0-g level at 2.5V Figure 15. Y axis sensitivity at 2.5V Figure 16. Z axis 0-g level at 2.5V Figure 17. Z axis sensitivity at 2.5V
8.2 Mechanical characteristics de rived from measurement in the
Figure 18. X axis 0-g level change vs Figure 19. X axis Sensitivity change vs Figure 20. Y axis 0-g level change vs Figure 21. Y axis sensitivity change Vs Figure 22. Z axis 0-g level change vs Figure 23. Z axis sensitivity change vs
8.3 Electro-mechanical characteristics at 25°C
Figure 24. Current consumption in normal Figure 25. Current consumption in power
9 Package information
conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. Figure 26. LGA 14: Mechanical data and package dimensions
Table 59. Document revision history 3-Oct-2006 1 Initial release.