SP8510KN Просмотр технического описания (PDF) - Signal Processing Technologies
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SP8510KN Datasheet PDF : 12 Pages
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Input Voltage Range Defined As:
Analog Input Connected to Pin
Pin Connected to AGND
One Least Significant Bit (LSB)
INPUT VOLTAGE RANGE AND LSB VALUES
FSR/212
±10V
2
3
20V/212
4.88mV
FFEH TO FFFH
7FFH TO 800H
000H to 001H
OUTPUT TRANSITION VALUES
+ FULL SCALE
Mid Scale
(Bipolar Zero)
–Full Scale
+10V–3/2LSB
+9.9927V
0V–1/2LSB
–2.44mV
–10V+1/2LSB
-9.9976V
Table 2. Input Voltages, Transition Voltages and LSB Values
±5V
3
2
10V/212
2.44mV
+5V–3/2LSB
+4.9963V
0V–1/2LSB
–1.22mV
–5V+1/2LSB
-4.9988V
Calibration Procedure
Apply a precision input voltage source to your
chosen input range (±10V range at pin 2 or ±5V
at pin 3). Set the A/D to convert continuously.
Monitor the output code. Trim the offset first,
then gain. Use the appropriate input voltages
and output target codes for your chosen input
range as follows. The recommended offset cali-
bration voltage values eliminate interaction be-
tween the offset and gain calibration
±5V Range Offset and Gain
Offset — Apply 1.5637V to the ±5V input at pin
3. Adjust the offset potentiometer until the LSB
toggles on and off at code 1010 1000 0000 =
BIN
A80 = 2688 .
H
DEC
Gain — Apply 4.9963V to the ±5V input at pin
3. Adjust the gain potentiometer until the LSB
toggles on and off at code 1111 1111 1110 =
BIN
FFE = 4094 .
H
DEC
±10V Range Offset and Gain
Offset — Apply 1.2622V to the ±10V input at
pin 2. Adjust the offset potentiometer until the
LSB toggles on and off at code 1001 0000
0010 = 902 = 2306 .
BIN
H
DEC
Gain — Apply 9.9927V to the ±10V input at pin
2. Adjust the gain potentiometer until the LSB
toggles on and off at code 1111 1111 1110 =
BIN
FFE = 4094 .
H
DEC
Layout Considerations
Because of the high resolution and linearity of
the SP85XX Series, system design problems
such as ground path resistance and contact resis-
tance become very important.
GAIN ADJUST
±10V
Input R2=100Ω
+5V
R1=10KΩ
499Ω
10KΩ
100Ω
–15V
1 SP85XX
2
3
4
5
6
7 a)
GAIN ADJUST
±5V
Input R2=100Ω
+5V
R1=10KW
1KΩ
30.1KΩ 301Ω
–15V
BIPOLAR ZERO ADJUST
1 SP85XX
2
3
4
5
6
7 b)
Figure 3. a) ±10V Range b) ±5V Range — With External Trims
49
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