ADXRS624

Rev. A | Page 10 of 12

behavior. Typical ratiometricity error for null, sensitivity, self-

test, and temperature output is outlined in Table 4.

Table 4. Ratiometricity Error for Various Parameters

Parameter

V

V

ST1

Mean

−0.4%

−0.3%

Sigma

0.6%

0.6%

ST2

Mean

−0.4%

−0.3%

Sigma

0.6%

0.6%

Null

Mean

−0.04%

−0.02%

Sigma

0.3%

0.2%

Sensitivity

Mean

0.03%

0.1%

Sigma

0.1%

0.1%

V

TEMP

Mean

−0.3%

−0.5%

Sigma

0.1%

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 ADXRS624 includes a self-test feature that actuates each of

the sensing structures and associated electronics as if subjected

to angular rate. The self-test feature 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 −1.9 V, and ST2 causes an opposite change of +1.9 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 of greater than

ST2 pins. The voltage applied to ST1 and ST2 must never be

CONTINUOUS SELF-TEST

The one-chip integration of the ADXRS624 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 the AN-768 Application Note.