SCA61T Series
2
Functional Description
2.1 Measuring Directions
X-axis
VOUT >
VOUT =2.5V
> VOUT
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:
⎛
⎞
Vout − Offset
Sensitivity
⎜
⎜
⎟
⎟
α = arcsin
⎝
⎠
where: Offset = output of the device at 0° inclination position, Sensitivity is the sensitivity of the
device and VDout is the output of SCA61T. The nominal offset is 2.5 V and the sensitivity is 4 V/g
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:
Vout −Offset
α =
Sensitivity
Where: Sensitivity = 70mV/° with SCA61T-FAHH1G or Sensitivity= 35mV/° with SCA61T-FA1H1G
Tilt angle [°]
Straight line conversion error [°]
0
0
1
2
3
4
0.0027
0.0058
0.0094
0.0140
0.0198
0.0787
0.2185
1.668
5
10
15
30
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.
VTI Technologies Oy
www.vti.fi
Subject to changes
Doc. nr. 8261900
9/18
Rev.A
VTI [ VTI TECHNOLOGIES ]
