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ADXRS610
ADXRS610 AND SUPPLY RATIOMETRICITY
The ADXRS610 RATEOUT and TEMP signals are ratiometric
to the V
RATIO
voltage, that is, the null voltage, rate sensitivity, and
temperature outputs are proportional to V
RATIO
. Thus, the
ADXRS610 is most easily used with a supply-ratiometric ADC
that results in self-cancellation of errors due to minor supply
variations. There is some small error due to nonratiometric
behavior. Typical ratiometricity error for null, sensitivity, self-
test, and temperature output is outlined in Table 3.
Rev. 0 | Page 10 of 12
Note that V
RATIO
must never be greater than AV
CC.
Table 3. Ratiometricity Error for Various Parameters
Parameter
V
S
= V
RATIO
= 4.75 V
ST1
Mean
0.4%
Sigma
0.6%
ST2
Mean
0.4%
Sigma
0.6%
Null
Mean
0.04%
Sigma
0.3%
Sensitivity
Mean
0.03%
Sigma
0.1%
V
TEMP
Mean
0.3%
Sigma
0.1%
V
S
= V
RATIO
= 5.25 V
0.3%
0.6%
0.3%
0.6%
0.02%
0.2%
0.1%
0.1%
0.5%
0.1%
NULL ADJUSTMENT
The nominal 2.5 V null is for a symmetrical swing range at
RATEOUT (1B, 2A). However, a nonsymmetrical output swing
may be suitable in some applications. Null adjustment is
possible by injecting a suitable current to SUMJ (1C, 2C). Note
that supply disturbances may reflect some null instability.
Digital supply noise should be avoided particularly in this case.
SELF-TEST FUNCTION
The ADXRS610 includes a self-test feature that actuates each of
the sensing structures and associated electronics as if subjected
to angular rate. It is activated by standard logic high levels
applied to Input ST1 (5F, 5G), Input ST2 (4F, 4G), or both. ST1
causes the voltage at RATEOUT to change about –0.5 V, and
ST2 causes an opposite change of +0.5 V. The self-test response
follows the viscosity temperature dependence of the package
atmosphere, approximately 0.25%/°C.
Activating both ST1 and ST2 simultaneously is not damaging.
ST1 and ST2 are fairly closely matched (±5%), but actuating
both simultaneously may result in a small apparent null bias
shift proportional to the degree of self-test mismatch.
ST1 and ST2 are activated by applying a voltage equal to V
RATIO
to the ST1 and ST2 pins. The voltage applied to ST1 and ST2
must never be greater than AV
CC
.
CONTINUOUS SELF-TEST
The on-chip integration of the ADXRS610 gives it higher reliability
than is obtainable with any other high volume manufacturing
method. In addition, it is manufactured under a mature BiMOS
process with field-proven reliability. As an additional failure
detection measure, a power-on self-test can be performed.
However, some applications may warrant continuous self-test
while sensing rate. Details outlining continuous self-test
techniques are also available in a separate application note.