ADIS16367BMLZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'ADIS16367BMLZ' PDF : 20 Pages View PDF
Data Sheet
ADIS16367
Internal Sample Rate
Digital Filtering
The SMPL_PRD register provides discrete sample rate settings
The N blocks in Figure 14 are part of the programmable low-pass
using the bit assignments in Table 18 and the following equation:
filter, which provides additional noise reduction on the inertial
tS = tB × (NS + 1)
For example, when SMPL_PRD[7:0] = 0x0A, the sample rate is
149 SPS.
sensor outputs. This filter contains two cascaded averaging filters
that provide a Bartlett window, FIR filter response (see Figure 15).
For example, set SENS_AVG[2:0] = 100 (DIN = 0xB804) to set
each stage to 16 taps. When used with the default sample rate
Table 18. SMPL_PRD Bit Descriptions
Bits
Description (Default = 0x0001)
[15:8] Not used
of 819.2 SPS, this value reduces the sensor bandwidth to
approximately 16 Hz.
0
[7]
Time base (tB)
0 = 0.61035 ms, 1 = 18.921 ms
[6:0]
Increment setting (NS)
Internal sample period = tS = tB × (NS + 1)
The default sample rate setting of 819.2 SPS preserves the sensor
E bandwidth and provides optimal performance. For systems that
value slower sample rates, keep the internal sample rate at
819.2 SPS. Use the programmable filter (SENS_AVG) to reduce
T the bandwidth, which helps to prevent aliasing. The data-ready
function (MSC_CTRL) can drive an interrupt routine that uses
a counter to help ensure data coherence at the reduced rates.
Power Management
E Setting SMPL_PRD ≥ 0x0A also sets the sensor to low power
mode. For systems that require lower power dissipation, in-
system characterization helps users to quantify the associated
L performance trade-offs. In addition to sensor performance, this
mode affects SPI data rates (see Table 2). Set SLP_CNT[8] = 1
(DIN = 0xBB01) to start the indefinite sleep mode, which requires
a CS assertion (high to low), reset, or power cycle to wake up.
O Use SLP_CNT[7:0] to put the device into sleep mode for a
specified period. For example, SLP_CNT[7:0] = 0x64
(DIN = 0xBA64) puts the ADIS16367 to sleep for 50 sec.
S Table 19. SLP_CNT Bit Descriptions
Bits
Description
[15:9] Not used
B [8]
Indefinite sleep mode; set to 1
[7:0] Programmable sleep time bits, 0.5 sec/LSB
Sensor Bandwidth
O The signal chain for each MEMS sensor has several filter stages,
–20
–40
–60
–80
–100
N=2
–120
N=4
N = 16
N = 64
–140
0.001
0.01
0.1
1
FREQUENCY (Ratio)
Figure 15. Bartlett Window, FIR Filter Frequency Response
(Phase Delay = N Samples)
Dynamic Range
The SENS_AVG[10:8] bits provide three dynamic range settings
for this gyroscope. The lower dynamic range settings (±300°/sec
and ±600°/sec) limit the minimum filter tap sizes to maintain
resolution. For example, set SENS_AVG[10:8] = 010 (DIN =
0xB902) for a measurement range of ±600°/sec. Because this
setting can influence the filter settings, program SENS_AVG[10:8]
and then SENS_AVG[2:0] if more filtering is required.
Table 20. SENS_AVG Bit Descriptions
Bits
Description (Default = 0x0402)
[15:11] Not used
[10:8] Measurement range (sensitivity) selection
100 = ±1200°/sec (default condition)
010 = ±600°/sec, filter taps ≥ 4 (Bits[2:0] ≥ 0x02)
001 = ±300°/sec, filter taps ≥ 16 (Bits[2:0] ≥ 0x04)
[7:3]
Not used
which shape their frequency response. Figure 14 provides a
[2:0]
Number of taps in each stage; value of m in N = 2m
block diagram for both gyroscope and accelerometer signal
paths. Table 20 provides additional information for digital filter
configuration.
FROM
GYROSCOPE
SENSOR
LPF
404Hz
LPF
757Hz
N
N
FROM
ACCELERATION
SENSOR
LPF
330Hz
N
N
N = 2m
m = SENS_AVG[2:0]
Figure 14. MEMS Analog and Digital Filters
Rev. B | Page 13 of 20
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