LTC2414 LINER [Linear Technology], LTC2414 Datasheet - Page 31

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

APPLICATIO S I FOR ATIO
mode rejection and by carefully eliminating common
mode to differential mode conversion sources in the input
circuit. The user should avoid single-ended input filters
and should maintain a very high degree of matching and
symmetry in the circuits driving the IN
Second, the increase in clock frequency will increase
proportionally the amount of sampling charge transferred
through the input and the reference pins. If large external
input and/or reference capacitors (C
previous section provides formulae for evaluating the
effect of the source resistance upon the converter perfor-
mance for any value of f
or reference capacitors (C
the external source resistance upon the LTC2414/LTC2418
typical performance can be inferred from Figures 12, 13,
18 and 19 in which the horizontal axis is scaled by 153600/
f
Third, an increase in the frequency of the external oscilla-
tor above 460800Hz (a more than 3× increase in the
output data rate) will start to decrease the effectiveness of
the internal autocalibration circuits. This will result in a
progressive degradation in the converter accuracy and
linearity. Typical measured performance curves for output
data rates up to 100 readings per second are shown in
Figures 23, 24, 25, 26, 27, 28, 29 and 30. In order to obtain
the highest possible level of accuracy from this converter
at output data rates above 20 readings per second, the
user is advised to maximize the power supply voltage used
and to limit the maximum ambient operating temperature.
In certain circumstances, a reduction of the differential
reference voltage may be beneficial.
Input Bandwidth
The combined effect of the internal Sinc
of the analog and digital autocalibration circuits deter-
mines the LTC2414/LTC2418 input bandwidth. When the
internal oscillator is used with the notch set at 60Hz
(F
internal oscillator is used with the notch set at 50Hz
(F
external conversion clock generator of frequency f
connected to the F
• 10
EOSC
O
O
= LOW), the 3dB input bandwidth is 3.63Hz. When the
–6
= HIGH), the 3dB input bandwidth is 3.02Hz. If an
.
• f
EOSC
.
O
U
pin, the 3dB input bandwidth is 0.236
EOSC
U
IN
, C
. If small external input and/
REF
) are used, the effect of
W
IN
, C
+
REF
4
and IN
digital filter and
) are used, the
U
–
pins.
EOSC
is
Figure 23. Offset Error vs Output Data Rate and Temperature
Figure 24. +FS Error vs Output Data Rate and Temperature
Figure 25. –FS Error vs Output Data Rate and Temperature
–10000
–12000
–4000
–6000
–8000
–2000
12000
10000
–2000
2000
8000
6000
4000
2000
–120
–160
–200
200
160
120
–40
–80
80
40
0
0
0
0
0
0
V
V
V
V
SDI = GND
F
V
V
V
V
SDI = GND
F
V
V
V
V
SDI = GND
F
O
O
O
CC
REF
IN
INCM
CC
REF
IN
INCM
CC
REF
IN
INCM
10
10
10 20 30 40 50 60 70 80 90 100
= EXTERNAL OSCILLATOR
= EXTERNAL OSCILLATOR
= EXTERNAL OSCILLATOR
OUTPUT DATA RATE (READINGS/SEC)
OUTPUT DATA RATE (READINGS/SEC)
OUTPUT DATA RATE (READINGS/SEC)
= 2.5V
= 2.5V
= 2.5V
LTC2414/LTC2418
= 5V
= 5V
= 5V
= 5V
= 5V
= 5V
= 2.5V
= 2.5V
= 2.5V
20
20
30 40
30 40
T
T
A
50
50
A
= 25°C
= 25°C
60
60
T
T
A
A
70
70
= 85°C
T
= 85°C
A
T
= 85°C
A
80
80
= 25°C
2414/18 F23
2414/18 F24
2414/18 F25
90
90
100
100
31
241418fa