Features

* Three -axis induction

* Small and low -key packaging

* 4mm × 4mm × 1.45 mm LFCSP

* Low power consumption: Typical 350μA

* Single power operation: 1.8 V to 3.6 V v

* 10000 grams of electric shock survival

* Excellent temperature stability

* Each axis per shaft Bandwidth adjustment with a capacitor

* meets the ROHS/Weee lead standard

Application

* cost sensitive, low in cost, low Application of power consumption, sports and tilt sensors

* Mobile device

* Game system

*[ 123] Disk drive protection

*

Stability of the image

sports and health equipment

] ADXL327

is a small, low -power, complete three -axis acceleration meter with signal adjustment voltage output. The minimum full -scale range of the product measurement acceleration is ± 2g. It can measure the static gravity acceleration in the application of tilt sensing, as well as dynamic acceleration generated by motion, impact or vibration.

The user uses the bandwidth of the acceleration meter on the CX, CY, and CZ capacitors on the Xout, YouT, and ZOUT pins. You can choose applications suitable for the range of 0.5 Hz to 1600 Hz and the z axis that are suitable for X and Y axis to 0.5 Hz to 550 Hz.

ADXL327 has 4 mm × 4 mm × 1.45 mm, 16 lead, plastic lead frame chip chip chip size packaging (LFCSP_LQ) to choose from.

Function box diagram

pin configuration and function description

Typical performance features

n gt; 1000, unless there is another explanation.

Operation theory

adxl327 is a complete three -axis acceleration measurement system. The minimum measurement range of ADXL327 is± 2 g. It contains polysilicon surface micro -mechanical sensors and signal conditioning circuits to realize the measuring architecture of the opening of the ring. The output signal is an analog voltage proportional to the acceleration. The acceleration meter can measure the static acceleration of the gravity in the application of the tilt sensor, and the dynamic acceleration generated by the movement, impact or vibration.

This sensor is a polysilicon surface micro -mechanical structure, built on a silicon wafer. The polycrystalline silicon spring hangs the structure on the wafer surface and provides resistance to acceleration. The deflection of the structure is measured with a differential capacitor. The capacitor consists of an independent fixed plate and a board attached to the mobile quality. The fixed board is driven by 180 ° different phase wave. The acceleration makes the movement of the movement, and the differential capacitor loses a balance, which generates a sensor output that generates an amplitude and acceleration. Then use phase sensitive demodulation technology to determine the acceleration and direction.

The output of the demodulator is enlarged and brought away from the chip through a 32 kΩ resistor. The user then adds a capacitor to set the signal bandwidth of the device. This filter can improve measurement resolution and help prevent confusion.

Mechanical sensor

ADXL327 uses a single structure to sense X, Y, and Z axis. Therefore, the three -axis sensing direction is highly positive, and the sensitivity of the cross -axis is very low. The mechanical deviation of sensor mold and packaging is the main source of the sensitivity of cross -axis. Of course, the mechanical deviation can be calibrated at the system level.

Performance

Innovative design technology does not use additional temperature compensation circuits, but to ensure that the ADXL327 has a built -in high performance. As a result, there is no quantization error nor non-monotonous behavior, and the temperature lag is very low (usually within the temperature range of -25 ° C to+70 ° C lt; 3 mg).

Application information

Power supply decoupling

In most applications, a 0.1 μF capacitor CDC is placed near the ADXL327 power pins, which is enough to accelerate the acceleration meter with the acceleration meter with Noise separation on the power supply. However, in applications with noise in the internal clock frequency (or any harmonic) in the 50 kHz, you need to pay attention to the power bypass, because this noise may cause the acceleration measurement error. If you need extra decoupling, you can insert a 100Ω (or smaller) resistor or iron oxygen magnetic beads on the power line. In addition, you can add larger large -capacity bypass containers (1 μF or larger) to CDC. Make sure that the connection from ADXL327 to the power supply is low impedance, because the noise transmitted through grounding has a similar effect with the noise transmitted through VS.

Use C, C, and C to set the Z axis with bandwidth ten

ADXL327 to have regulations that restrict the frequency band of Xout, YouT, and ZOUT pins. Capacors must be added to these feet to achieve low -pass filtering to eliminate hybrids and noise. 3DB bandwidth equations are:

or simpler

The tolerance of the internal resistor (R) usually changes to its nominal value ( ± 15%of 32 kΩ), the bandwidth also changed accordingly. In all cases, the minimum capacitance of CX, CY and CZ is 0.0047μF.

Self -test

ST pin control self -test function. When the pin is set to VS, the electrostatic power is applied to the acceleration beam. As a result, the beam movement allows users to test whether the acceleration meter works properly. The typical changes of the output are -1.08 g (corresponding to -450 MV) on the X axis, +1.08 g (+450 mv) on the Y axis, and +1.83 g (+770 mv) on the Z axis. When using it normally, this ST pin can keep the road or connect to the public (COM).

Do not expose the ST pin to a voltage greater than VS+0.3 V. If this is not guaranteed due to the system design (for example, multiple power supply voltage) cannot be guaranteed, it is recommended to use a low VF clamp diode between ST and VS.

Design weighing of the characteristics of the filter: noise/bw weighing

Selected acceleration meter bandwidth finally determines the measurement resolution (minimum detection acceleration). Filter can reduce the noise floor and improve the resolution of the acceleration meter. The resolution depends on the analog filter bandwidth at the XOUT, YouT and ZOUT.

The output of ADXL327 has a typical bandwidth greater than 500 Hz. The user must filter the signal at this time to limit the overlapping error. The simulation bandwidth shall not exceed half of the frequency of the simulation to the digital sampling, and minimize it. It can further reduce the simulation bandwidth to reduce noise and increase resolution.

ADXL327 noise has the characteristics of white high noise. At all frequencies, the contribution of white Gaos noise is equal, and it is described by μg/√Hz (the square root of the noise and acceleration meter bandwidth). Users should limit the bandwidth to the minimum frequency required by the application to maximize the resolution and dynamic range of the acceleration meter.

The typical noise of ADXL327 is used with a single pole roll characteristics. The noise in the peak can only be estimated by statistical methods. Table 5 helps to estimate the probability of exceeding various peak values when a given average root value.

Use working voltage other than 3V

ADXL327 test and regulate at V 3V; however, it can be used as low as 1.8V or up to 3.6 high. V's voltage power supply. Note that some performance parameters change as the power supply voltage changes.

ADXL327 output is measured by ratio; therefore, the output sensitivity (or proportional factor) varies with the power supply voltage. When V 3.6 V, the output sensitivity is usually 500 mv/g. When V 2 V, the output sensitivity is usually 289 mv/g.

Zero -G bias output is also the ratio output; therefore, zero G output is nominally equal to V/2 under all power supply voltage.

The output noise is not measured, but the absolute value of the volt as a unit; therefore, the noise density decreases as the power supply voltage increases. This is because when the noise voltage remains constant, the marking factor (MV/G) increases. When V 3.6V, the noise density of the X and Y Axis is usually 200 μg/√Hz, and when V 2V, the X -axis and Y -axis noise density is usually 300 μg/√Hz.

Self -test response (G) is generally proportional to the square of the power supply voltage. However, when the amount of sensitivity is combined with the power supply voltage, the self -test response of volt -in -units is roughly proportional to the cube of the power supply voltage.

For example, when VS 3.6 V, the self-test response of ADXL327 is about -780 MV for the X axis, the Y axis is about +780 MV, and the Z axis is about +1330 MV. When VS 2 V, the self-proven response of the X axis is about -130 MV, the self-proven response of the Y-axis is about +130 MV, and the self-propelled response of the Z-axis is about -220 MV.

As the power supply voltage decreases, the power supply current decreases. The typical current consumption of VS 3.6V is 375 μA, and the typical current consumption of the typical current at VS 2V is 300 μA.

Layout and design recommendations

The recommended welding shape is shown in Figure 25, and then the description of the characteristics of the shape in Table 6. The recommended PCB layout or welding ring diagram is shown in Figure 26.

[1] defined as between any two axes coupling. [2] The sensitivity is basically the ratio of V.

[3] defined as the output change from ambient temperature to maximum temperature or from ambient temperature to minimum temperature.

[4] The actual frequency response controlled by the external filter capacitor (C, C, C) provided by the user.

[5] The bandwidth of the external capacitor 1/(2 × π × 32 kΩ × c). For C, C 0.003μF, bandwidth 1.6 kHz. For C 0.01 μF, bandwidth 500 Hz. For C, C, C 10 μF, bandwidth 0.5 Hz.

[6] Self -test response has a three -dimensional change with V.

[7] The opening time depends on C, C, C, about 160 × C or C or C+1 ms, where C, C, C are μF.

[8] Z parts that conform to ROHS.