ADXL346ACCZ-R2 datasheet(35/40 Pages) AD

35 / 40 page

Data Sheet

ADXL346

NOISE PERFORMANCE

The specification of noise shown in Table 1 corresponds to the

typical noise performance of the ADXL346 in normal power

operation with an output data rate of 100 Hz (LOW_POWER

bit = 0, rate = 0x0A in the BW_RATE register, Address 0x2C).

For normal power operation at data rates below 100 Hz, the noise

of the ADXL346 is equivalent to the noise at 100 Hz ODR in

LSBs. For data rates greater than 100 Hz, the noise increases

approximately by a factor of √2 per doubling of the data rate.

For example, at 400 Hz ODR, the noise on the x- and y-axes is

typically less than 2 LSB rms, and the noise on the z-axis is

typically less than 3 LSB rms.

For low power operation (LOW_POWER bit = 1 in the BW_RATE

for all valid data rates shown in Table 8. This value is typically

less than 2.83 LSB rms for the x- and y-axes and typically less

than 4.25 LSB rms for the z-axis.

The trend of noise performance for both normal power and low

power modes of operation of the ADXL346 is shown in Figure 54.

Figure 55 shows the typical Allan deviation for the ADXL346.

The 1/f corner of the device, as shown in this figure, is very low,

allowing absolute resolution of approximately 100 µg (assuming

that there is sufficient integration time). The figure also shows

that the noise density is 420 µg/√Hz for the x- and y-axes and

530 µg/√Hz for the z-axis.

Figure 56 shows the typical noise performance trend of the

ADXL346 over supply voltage. The performance is normalized

to the tested and specified supply voltage, VS = 2.6 V. The x-axis

offers the best noise performance over supply voltage, increasing by

typically less than 25% from nominal at a supply voltage of 1.8 V.

The performance of the y- and z-axes is comparable, with both

axes increasing by typically less than 35% when operating with a

supply voltage of 1.8 V. It should be noted, as shown in Figure 54,

that the noise on the z-axis is typically higher than that on the

y-axis; therefore, although the noise on the z- and y-axes change

roughly the same in percentage over supply voltage, the magnitude

of change on the z-axis is greater than the magnitude of change

on the y-axis.

OUTPUT DATA RATE (Hz)

X-AXIS, NORMAL POWER

X-AXIS, LOW POWER

Y-AXIS, NORMAL POWER

Y-AXIS, LOW POWER

Z-AXIS, NORMAL POWER

Z-AXIS, LOW POWER

3.13 6.25 12.50

100

200

400

1600

800

3200

Figure 54. Noise vs. Output Data Rate for Normal and Low Power Modes,

Full Resolution (256 LSB/g)

0.01

0.1

100

10k

100

10k

AVERAGING PERIOD,

(s)

X-AXIS

Y-AXIS

Z-AXIS

Figure 55. Allan Deviation

100

110

120

130

140

150

1.6

1.8

2.0

2.2

2.4

2.6

2.8

SUPPLY VOLTAGE, VS (V)

X-AXIS

Y-AXIS

Z-AXIS

Figure 56. Normalized Noise vs. Supply Voltage

Rev. C | Page 35 of 40

ADXL346ACCZ-R2 データシート(PDF) 35 Page - Analog Devices

ADXL346ACCZ-R2 データシート(HTML) 35 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

データシートダウンロード