LTC2494CUHF-PBF LINER [Linear Technology], LTC2494CUHF-PBF Datasheet - Page 33

• Manufacturer Part Number: LTC2494CUHF-PBF
• Description: 16-Bit 8-/16-Channel ?? ADC with PGA and Easy Drive Input Current Cancellation
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
rejection of line frequencies remains unchanged, thus fully
differential input signals with a high degree of symmetry
on both the IN
frequency noise.
An increase in f
input and reference current. External RC networks will
continue to have zero differential input current, but the
time required for complete settling (580ns for f
307.2kHz) is reduced, proportionally.
Once the external oscillator frequency is increased above
1MHz (a more than 3x increase in output rate) the effective-
ness of internal auto calibration circuits begins to degrade.
This results in larger offset errors, full scale errors, and
decreased resolution (see Figures 31 to 38).
–100
–120
–100
–120
– 60
– 60
–20
–40
–80
–20
–40
–80
Figure 27. Measure Input Normal Mode Rejection vs Input
Frequency With input Perturbation of 150% (50Hz Notch)
Figure 26. Measure Input Normal Mode Rejection vs Input
Frequency with Input Perturbation of 150% (60Hz Notch)
0
0
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
15
30
45
+
EOSC
and IN
60
also increases the effective dynamic
75
–
90
INPUT FREQUENCY (Hz)
INPUT FREQUENCY (Hz)
pins will continue to reject line
105 120 135 150 165 180 195 210 225 240
V
V
(150% OF FULL SCALE)
V
V
(150% OF FULL SCALE)
IN(P-P)
IN(P-P)
IN(P-P)
IN(P-P)
= 5V
= 7.5V
= 5V
= 7.5V
V
V
V
T
V
V
V
T
CC
REF
IN(CM)
A
CC
REF
IN(CM)
A
= 25°C
= 25°C
= 5V
= 5V
EOSC
= 5V
= 5V
= 2.5V
= 2.5V
2494 F26
2494 F27
=
Figure 30. Input Normal Mode Rejection 2x Speed Mode with
and Without Running Averaging
Figure 28. Input Normal Mode Rejection 2x Speed Mode
Figure 29. Input Normal Mode Rejection 2x Speed Mode
–100
–120
–100
–120
–40
–60
–80
–20
–100
–110
–120
–130
–140
–40
–60
–20
–80
–80
–90
–70
0
0
248
0
48
DIFFERENTIAL INPUT SIGNAL FREQUENCY (Hz)
250
f
N
50
INPUT SIGNAL FREQUENCY (f
INPUT SIGNAL FREQUENCY (f
2f
252 254 256 258 260 262 264
N
52
3f
N
54
4f
N
NO AVERAGE
56
5f
N
58
RUNNING
6f
AVERAGE
N
WITH
N
N
)
)
60
7f
LTC2494
N
2494 F28
2494 F29
2494 F30
8f
62
N
33
2494fb