ADXL180WCPZ-RL Analog Devices Inc, ADXL180WCPZ-RL Datasheet - Page 41

• Manufacturer Part Number: ADXL180WCPZ-RL
• Description: IC ACCELEROMETER CONFIG 16-LFCSP
• Manufacturer: Analog Devices Inc
• Series: iMEMS®r

Specifications of ADXL180WCPZ-RL

• Axis: X or Y
• Acceleration Range: ±50g, 100g, 150g, 200g, 250g, 350g, 500g
• Voltage - Supply: 5 V ~ 14.5 V
• Output Type: Analog
• Bandwidth: 100Hz ~ 800Hz Selectable
• Mounting Type: Surface Mount
• Package / Case: 16-LFQFN, CSP Exposed Pad
• Package Type: LFCSP EP
• Operating Supply Voltage (min): 5V
• Operating Temperature (min): -40C
• Operating Temperature (max): 125C
• Operating Temperature Classification: Automotive
• Product Depth (mm): 5mm
• Product Height (mm): 1.43mm
• Product Length (mm): 5mm
• Mounting: Surface Mount
• Pin Count: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Sensitivity: -
• Interface: -
• Lead Free Status / Rohs Status: Compliant
• Other names: ADXL180WCPZ-RLCT

SIGNAL RANGE AND FILTERING
TRANSFER FUNCTION OVERVIEW
The three-pole, low-pass Bessel filter has a selectable −3 dB
corner (f
800 Hz by programming the filter corner (FC) bits in the
configuration registers. In the pass band between f
response of the ADXL180 is flat with the nominal scale factor
defined by the settings of the range (RG) bits in the
configuration registers (see Figure 31). The auto-zero function
creates a first-order high-pass filter with a −3 dB corner at f
Note that the output of this filter is slew rate limited. The auto-
zero function can be disabled by setting the appropriate bit in
the configuration registers. See the Specifications section for
more information.
RANGE
Table 37. RG[2:0] Sensor Range Select Codes
The ADXL180 is configurable into the g-ranges shown in Table 37.
Adjusting the device g-range alters the g/LSB scale factor.
Selecting the 50 g range offers increased data resolution of
0.125 g/LSB; however, input signals above 50 g appear clipped
on the output of the device. Selecting a higher g-rating decreases
the resolution of data; however, it allows for a wider full-scale
range of observable signals.
RG2
0
0
0
0
1
1
1
1
SENSITIVITY
NOMINAL
LSB/g
LP
). The corner can be set to 100 Hz, 200 Hz, 400 Hz, or
Figure 31. Bode Plot of ADXL180 Transfer Function
RG1
0
0
1
1
0
0
1
1
f
HP
AUTO-ZERO FILTER
+20dB/DECADE
FREQUENCY
RG0
0
1
0
1
0
1
0
1
–3dB
f
LP
±50 g
±100 g
±250 g
±150 g
±200 g
±350 g
±500 g
Not used
Range
–60dB/DECADE
BESSEL FILTER
HP
and f
LP
LP
, the
Rev. A | Page 41 of 60
.
THREE-POLE BESSEL FILTER
Table 38. FC Low-Pass Filter Bandwidth Frequency Select
Codes
FC1
0
0
1
1
By configuring the FC1 and FC0 bits as shown in Table 38, the
output filter on the ADXL 180 can be set. This adjusts the −3 dB
frequency of the output filter to the desired bandwidth. The
ADXL180 low-pass filter is a third-order, low-pass Bessel filter
with a −60 dB per decade roll-off. See the Specifications table
for more information on the tolerances of the low-pass filter
bandwidth.
AUTO-ZERO OPERATION
The auto-zero function is enabled by setting the appropriate bit
in the configuration registers, see Table 44. This function helps
reduce slow offset drifts due to aging, temperature, and so forth.
The acceleration signal offset is determined by passing the
acceleration signal through a one-pole digital low-pass filter.
The output of this filter is then slew rate limited. The slew rate
limited offset value is then subtracted from the acceleration
data. This forms a slew rate limited high-pass filter as shown in
Figure 32.
If auto-zero mode is enabled, a fast offset compensation is
performed during start up of Phase 4 (fast auto-zero mode).
The filter output is set to the last zero reading average
performed by the self-test (Phase 3). The −3 dB frequency of
the digital low-pass filter is approximately 0.08 Hz, and the slew
rate limiter output (and therefore the offset correction) is
updated every 0.5 seconds. The fast update mode (Phase 4) is
15 seconds long in asynchronous mode and 65,535 × t
synchronous mode (see the Phase 4: Auto-Zero Initialization
section).
If auto-zero mode is enabled, an offset compensation is
performed during normal operation (Phase 5). This offset
compensation is performed at a slower rate than during the
auto-zero initialization (Phase 4). The −3 dB frequency of the
digital low-pass filter is approximately 0.01 Hz and the slew rate
limiter output (and therefore the offset correction) is updated
every five seconds. The slow update mode persists until power
down. See the Phase 5: Normal Operation section.
The range of the offset corrected output is reduced compared to
when the auto-zero is disabled. This is the function of the
limiter block in Figure 32. This range reduction is shown in
Table 16 and Table 17.
FC0
0
1
0
1
−3 dB LP Frequency
400 Hz
200 Hz
100 Hz
800 Hz
ADXL180
PS
in