Texas Instruments SensorEmulatorEVM Evaluation Module SENSOREMULATOREVM SENSOREMULATOREVM Datenbogen
Produktcode
SENSOREMULATOREVM
SBOA102A
January 2005
January 2005
Sensor-Emulator-EVM
System Reference Guide
17
Figure 3.1 illustrates how the range of the bridge emulator can be adjusted by putting a resistor in parallel with R101 and R104. This needs to be
done for each channel of the emulator (11 channels x 2 resistors = 22 resistors total). The examples illustrates how the range is increased using a
1k
done for each channel of the emulator (11 channels x 2 resistors = 22 resistors total). The examples illustrates how the range is increased using a
1k
Ω parallel resistor. In general, it is best to select a parallel resistance value that scales your range so that the full scale output of the emulator is
slightly larger than what is required for your emulator. Scaling the emulator in this manner will provide the optimal resolution and lowest noise. Note
that holes are provided for a parallel through-hole resistor to simplify the process of adjusting the emulator scale.
that holes are provided for a parallel through-hole resistor to simplify the process of adjusting the emulator scale.
Positive full scale of the emulator
Vexc 5
:=
R104 10 10
3
⋅
:=
R102 200
:=
R101
10 10
3
⋅
:=
R102a
200
:=
Wiper position at top of POT
R103
10
:=
Pot set to maximum Resistance
Vdif
Vexc R104 R103
+
R102a
+
(
)
⋅
R101 R104
+
R103
+
R102
+
Vexc
2
−
:=
Vdif 0.026
=
Positive full scale output of emulator
Negative full scale of the emulator
Vexc 5
:=
R104 10 10
3
⋅
:=
R102 200
:=
R101 10 10
3
⋅
:=
R102a 0
:=
Wiper position at bottom of POT
R103
0
:=
Pot set to Minimum Resistance
Vdif
Vexc R104 R103
+
R102a
+
(
)
⋅
R101 R104
+
R103
+
R102
+
Vexc
2
−
:=
Vdif
0.025
−
=
Positive full scale output of emulator
Figure 3.0: Default Range
Figure 3.1: Adjusted Range
10k
10k
10k
10k
Output of Sensor
Vin+ to Signal
Conditioning Chip
Output of Sensor
Vin- to Signal
Conditioning Chip
Input To Bridge
Vexc
(Excitation voltage)
200 ohm
10 ohm
V
DIF
=
26mV
-25mV
to
2.526V
Wiper at top
2.475V
Wiper at bottom
to
2.5V
5.0V
R8
R9
R104
R103
R102
R101
2.5V
3.0 Changing the Programmable Range of the Emulator
Positive full scale of the emulator
Vexc 5
:=
R104 909.1
:=
R102 200
:=
R101 909.1
:=
R102a
200
:=
W iper position at to p of POT
R103 10
:=
Po t set to maximum Resistance
Vdif
Vexc R104 R103
+
R102a
+
(
)
⋅
R101 R104
+
R103
+
R102
+
Vexc
2
−
:=
Vdif 0.259
=
Positive full scale output of emulator
Negative full scale of the emulator
Vexc 5
:=
R104 909.1
:=
R102 200
:=
R101 909.1
:=
R102a 0
:=
W iper positio n at bottom of POT
R103 0
:=
Pot set to Minimum Resistance
Vdif
Vexc R104 R103
+
R102a
+
(
)
⋅
R101 R104
+
R103
+
R102
+
Vexc
2
−
:=
Vdif
0.248
−
=
N egative full scale output of emulator