LTC1415 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1415' PDF : 24 Pages View PDF
LTC1415
APPLICATIONS INFORMATION
4.096V to 2.048V and shifts the common mode voltage
from half of full scale to 2.274V.
AC Coupled Inputs
The analog inputs can be AC coupled for applications
where the input has no DC information. The input of the
80
70
60
50
40
30
20
10
0
1k
10k
100k
1M 2M
INPUT FREQUENCY (Hz)
LTC1415 • F10a
Figure 10a. CMRR vs Input Frequency
ADC does need to be DC biased at midscale. Figures 10d
and 10e demonstrate AC coupling and the required bias-
ing. Figure 10d shows the ADC with a full scale of 4.096V,
a common mode voltage of 2.048V and an input that
swings from 0V to 4.096V. This circuit has the lowest
noise (SINAD = 72dB to 100kHz) but will have distortion
ANALOG INPUT
0.2V TO 4.296V
1
+AIN
R1
200Ω
2
– AIN
R2
3
LTC1415
3.9k
VREF
10µF
4
REFCOMP
5
AGND
LTC1415 • F10b
Figure 10b. Shifting the Input Range Up from Ground by 200mV
ANALOG INPUT
1.25V TO 3.298V
1
+AIN
24Ω
VOUT = 1.2V
2
– AIN
3
VREF
LT1004-1.2
1µF
LTC1415
4
REFCOMP
10µF
5
AGND
LTC1415 • F10c
Figure 10c. 2.048V Input Range with a Common Mode
Voltage of 2.274V. For Low Distortion AC Applications
ANALOG INPUT
4.096VP-P
1
+AIN
2
– AIN
3
VREF
LTC1415
4
REFCOMP
2k
10µF
2k
5
AGND
LTC1415 • F10d
Figure 10d. 4.096VP-P Input Range with AC Coupling.
For Low Noise AC Applications
ANALOG INPUT
2.048VP-P
25Ω
1k LT1004-1.2
1
+AIN
2
– AIN
3
1µF
VREF
LTC1415
4
REFCOMP
10µF
1k
9k
5
AGND
LTC1415 • F10e
Figure 10e. 2.048VP-P Input Range with AC Coupling. For Low Distortion AC Applications
13
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