SCA61T Series

VTI Technologies Oy

Subject to changes

9/18

www.vti.fi

Doc. nr. 8261900

Rev.A

y

Sensitivit

Offset

V

=

α

2

Functional Description

2.1

Measuring Directions

X-axis

Figure 8.

The measuring direction of the SCA61T

2.2

Voltage to Angle Conversion

Analog output can be transferred to angle using the following equation for conversion:

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

y

Sensitivit

Offset

V

out

arcsin

α

where: Offset = output of the device at 0° inclination position, Sensitivity is the sensitivity of the

with SCA61T-FAHH1G and 2 V/g with SCA61T-FA1H1G.

Angles close to 0° inclination can be estimated quite accurately with straight line conversion but for

best possible accuracy arcsine conversion is recommended to be used. The following table shows

the angle measurement error if straight line conversion is used.

Straight line conversion equation:

Where: Sensitivity = 70mV/° with SCA61T-FAHH1G or Sensitivity= 35mV/° with SCA61T-FA1H1G

Tilt angle [°]

Straight line conversion error [°]

0

0

1

0.0027

2

0.0058

3

0.0094

4

0.0140

5

0.0198

10

0.0787

15

0.2185

30

1.668

2.3

Ratiometric Output

Ratiometric output means that zero offset point and sensitivity of the sensor are proportional to the

supply voltage. If the SCA61T supply voltage is fluctuating, the SCA61T output will also vary.

When the same reference voltage for both the SCA61T sensor and the measuring part (A/D-

converter) is used, the error caused by reference voltage variation is automatically compensated

for.

VOUT >

VOUT =2.5V

> VOUT