AD2S93BP AD [Analog Devices], AD2S93BP Datasheet - Page 11

• Manufacturer Part Number: AD2S93BP
• Description: Low Cost LVDT-to-Digital Converter
• Manufacturer: AD [Analog Devices]

The small step response is given in Figure 12, and is the time
taken for the converter to settled to within 1 LSB.
The large step response (steps >5% of FSR) applies when the
error voltage will exceed the linear range of the converter. Typi-
cally it will take three times longer to reach the first peak FSR.
In response to a velocity step [VELOUT/(d /dt)] the velocity
output will exhibit the same response characteristics as outlined
above.
REV. A
2%FS
0
0
Figure 12. Small Step Response
ts = 7 ms (14-bit resolution)
4
8
12
16
20
–11–
SOURCES OF ERROR
ACCELERATION ERROR
A tracking converter employing a Type 2 servo loop does not
suffer any velocity lag, however, there is an additional error due
to acceleration. This additional error can be defined using the
acceleration constant K
The numerator and denominator’s units must be consistent.
K
to its acceleration. The maximum acceleration allowable before
the converter loses track is dependent on the positional accuracy
requirement of the system.
K
given input acceleration. The AD2S93 in the example has
a K
100 2
a
a
can be used to predict the output position error for a
does not define maximum input acceleration, only the error due
a
= 13.44
14
Error in LSBs =
LSB/sec
10
2
6
Position Error K
.
sec
13.44 10
100
K
-2
a
a
if we apply an input accelerating at
of the converter.
input acceleration LSB/sec
input acceleration
2
14
6
position
K
a
0.12 LSBs
a
= LSB/sec
[
sec
[
-2
]
2
AD2S93
2
]