LTC2414 LINER [Linear Technology], LTC2414 Datasheet - Page 34

• Manufacturer Part Number: LTC2414
• Description: 8-/16-Channel 24-Bit No Latency TM ADCs
• Manufacturer: LINER [Linear Technology]

LTC2414/LTC2418
APPLICATIO S I FOR ATIO
The combined normal mode rejection performance is
shown in Figure 33 for the internal oscillator with 50Hz
notch setting (F
oscillator with 60Hz notch setting (F
external oscillator mode. The regions of low rejection
occurring at integer multiples of f
bandwidth. Magnified details of the normal mode rejection
curves are shown in Figure 35 (rejection near DC) and
Figure 36 (rejection at f
notch frequency. These curves have been derived for the
external oscillator mode but they can be used in all
operating modes by appropriately selecting the f
The user can expect to achieve in practice this level of
performance using the internal oscillator as it is demon-
strated by Figures 37 and 38. Typical measured values of
the normal mode rejection of the LTC2414/LTC2418
34
–100
–120
Figure 37. Input Normal Mode Rejection vs Input Frequency
with Input Perturbation of 100% Full Scale (60Hz Notch)
– 60
–20
–40
–80
0
0
15
Figure 35. Input Normal Mode Rejection
30
–100
–110
–120
45
–10
–20
–30
–40
–50
–60
–70
–80
–90
O
0
= HIGH) and in Figure 34 for the internal
0
60
U
f
N
75
INPUT SIGNAL FREQUENCY (Hz)
S
2f
90
N
INPUT FREQUENCY (Hz)
= 256f
U
3f
105 120 135 150 165 180 195 210 225 240
N
4f
N
N
) where f
5f
N
MEASURED DATA
CALCULATED DATA
S
W
6f
O
N
have a very narrow
= LOW) and for the
7f
2414/18 F35
N
N
8f
represents the
N
U
V
REF
REF
V
V
SDI = GND
F
T
O
A
CC
INCM
IN(P-P)
N
= GND
= 25°C
+
–
= 5V
value.
= 5V
= GND
= 2.5V
= 5V
2414/18 F37
operating with an internal oscillator and a 60Hz notch
setting are shown in Figure 37 superimposed over the
theoretical calculated curve. Similarly, typical measured
values of the normal mode rejection of the LTC2414/
LTC2418 operating with an internal oscillator and a 50Hz
notch setting are shown in Figure 38 superimposed over
the theoretical calculated curve.
As a result of these remarkable normal mode specifica-
tions, minimal (if any) antialias filtering is required in front
of the LTC2414/LTC2418. If passive RC components are
placed in front of the LTC2414/LTC2418, the input dy-
namic current should be considered (see Input Current
section). In cases where large effective RC time constants
are used, an external buffer amplifier may be required to
minimize the effects of dynamic input current.
–100
–120
Figure 38. Input Normal Mode Rejection vs Input Frequency
with Input Perturbation of 100% Full Scale (50Hz Notch)
– 60
–20
–40
–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
Figure 36. Input Normal Mode Rejection
–100
–110
–120
–10
–20
–30
–40
–50
–60
–70
–80
–90
250f
0
N
252f
INPUT SIGNAL FREQUENCY (Hz)
N
254f
INPUT FREQUENCY (Hz)
N
256f
N
258f
MEASURED DATA
CALCULATED DATA
N
260f
2414/18 F36
N
262f
N
V
REF
REF
V
V
SDI = GND
F
T
O
A
CC
INCM
IN(P-P)
= 5V
= 25°C
+
= 5V
–
= 5V
= GND
241418fa
= 2.5V
= 5V
2414/18 F38