PNI RM3000 Sensor Suites - Manual (Page 6)

PNI Sensor Corporation Doc #1015673 r08
RM3000 & RM2000 Sensor Suite User Manual – July 2012 Page 6 of 41
3 Specifications
3.1 Geomagnetic Sensor Suite Characteristics
Table 3-1: Geomagnetic Sensor Suite Performance 1
Parameter Min Typical Max Units
Field measurement range
2
-1100 +1100 T
Gain @ 200 Cycle Counts
3
45 counts/ T
Noise @ 200 Cycle Counts
3
35 nT
Maximum Sample Rate, Single Axis @
200 Cycle Counts
4
450 Hz
Linearity - best fit over 200 T 0.6 1.0 % of 200 T
Average Current per Axis @ 35 Hz and
@ 200 Cycle Counts
5
0.3 mA
Bias Resistance (R
B
)
2.6 V to 3.3 V 68
1.6 V to 2.6V 33 + (V-1.6)*35
External Timing Resistor for Clock (R
EXT
) 33 k
Circuit Oscillation Frequency 185 kHz
High Speed Clock Frequency 45 MHz
Operating Temperature -40 +85 C
Footnotes:
1. Specifications subject to change. Unless otherwise noted, performance characteristics assume
the user implements the recommended bias resistors and external timing resistor for the high-
speed clock (as indicated in Figure 4-1 ), the DC supply voltage is 3.3 V, and the 3D MagIC is
operated in Standard Mode. Other bias resistors, external timing resistors and operating voltages
may be used, but performance may differ from the values listed.
2. Field measurement range is defined as the monotonic region of the output characteristic curve.
3. Gain and noise are related to useable resolution. Below ~200 cycle counts the gain setting
dominates the usable resolution (resolution = 1/gain) while above ~200 cycle counts the system
noise dominates. The user establishes the gain value by setting the Cycle Count Register value.
See Figure 3-4 for the typical relationship between cycle counts, gain, and resolution. Above
~200 cycle counts noise is relatively constant and there are diminishing returns in usable
resolution as the cycle count value increases. Also, performance will vary from sensor to sensor:
~50% of the sensors will have performance greater
than “Typical” and ~50% less than “Typical”.
4. The maximum sample rate and gain/resolution are inversely related, so higher sample rates can
be obtained by reducing the number of cycle counts, but this also results in reduced gain and
resolution. Also see Figure 3-4 and Figure 3-5.
5. Operating at reduced cycle counts reduces current consumption, but also reduces resolution.
Operating at greater cycle counts increases current consumption but, due to system noise, does
not significantly increase useable resolution. Also see Figure 3-6.