LTC2487 Linear Technology, LTC2487 Datasheet - Page 27

• Manufacturer Part Number: LTC2487
• Description: 16-Bit 2-/4-Channel ADC
• Manufacturer: Linear Technology

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Figure 23. Input Normal Mode Rejection vs Input Frequency with
Input Perturbation of 100% (50Hz/60Hz Notch)
shown superimposed over the theoretical values in all
three rejection modes.
Traditional high order delta-sigma modulators suffer
from potential instabilities at large input signal levels.
The proprietary architecture used for the LTC2487 third
order modulator resolves this problem and guarantees
stability with input signals 150% of full scale. In many
applicaTions inForMaTion
–100
–120
–20
–40
– 60
–80
0
0
12.5 25 37.5 50 62.5 75 87.5 100 112.5 125 137.5 150 162.5 175 187.5 200
INPUT FREQUENCY (Hz)
Figure 25. Measure Input Normal Mode Rejection vs Input
Frequency with Input Perturbation of 150% (50Hz Notch)
–100
–120
–20
–40
– 60
–80
MEASURED DATA
CALCULATED DATA
0
0
12.5 25 37.5 50 62.5 75 87.5 100 112.5 125 137.5 150 162.5 175 187.5 200
V
V
V
V
T
CC
REF
IN(CM)
IN(P-P)
A
= 25°C
= 5V
= 5V
= 2.5V
= 5V
2487 F23
INPUT FREQUENCY (Hz)
industrial applications, it is not uncommon to have mi-
crovolt level signals superimposed over unwanted error
sources with several volts if peak-to-peak noise. Figures
24 and 25 show measurement results for the rejection
of a 7.5V peak-to-peak noise source (150% of full scale)
applied to the LTC2487. These curves show that the rejec-
tion performance is maintained even in extremely noisy
environments.
V
V
(150% OF FULL SCALE)
Figure 24. Measure Input Normal Mode Rejection vs Input
Frequency with Input Perturbation of 150% (60Hz Notch)
IN(P-P)
IN(P-P)
–100
–120
– 60
–20
–40
–80
0
= 5V
= 7.5V
0
15
30
45
V
V
V
T
CC
REF
IN(CM)
A
60
= 25°C
= 5V
= 5V
75
= 2.5V
2487 F25
90
INPUT FREQUENCY (Hz)
105 120 135 150 165 180 195 210 225 240
V
V
(150% OF FULL SCALE)
IN(P-P)
IN(P-P)
= 5V
= 7.5V
LTC2487
V
V
V
T
A
CC
REF
IN(CM)
= 25°C

= 5V
= 5V
= 2.5V
2487 F24
2487fa