ltc2484 Linear Technology Corporation, ltc2484 Datasheet - Page 36

• Manufacturer Part Number: ltc2484
• Description: 24-bit Delta Sigma Adc With Easy Drive Input Current Cancellation
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
LTC2484
mode. Typical measured values of the normal mode
rejection of the LTC2484 operating with the internal oscil-
lator and 2x speed mode is shown in Figure 41.
36
Figure 41. Input Normal Mode Rejection vs Input Frequency,
2x Speed Mode and 50Hz/60Hz Mode
–100
–120
–20
–40
– 60
–80
Figure 39. Input Normal Mode Rejection 2x Speed Mode
0
0
Figure 37. Measured Input Normal Mode Rejection vs
Input Frequency with Input Perturbation of 150% Full
Scale (60Hz Notch)
15
30
–100
–120
–100
–120
–20
–40
–60
–80
–20
–40
–60
–80
0
0
45
0
0
60
25
f
N
U
INPUT SIGNAL FREQUENCY (f
50
75
2f
MEASURED DATA
CALCULATED DATA
INPUT FREQUENCY (Hz)
N
75
90
3f
INPUT FREQUENCY (Hz)
U
N
100 125
105 120 135 150 165 180 195 210 225 240
4f
N
5f
V
V
(150% OF FULL SCALE)
150 175 200
N
IN(P-P)
IN(P-P)
V
V
V
V
F
T
O
A
CC
REF
INCM
IN(P-P)
6f
= GND
= 25°C
W
N
= 5V
= 5V
= 7.5V
N
= 5V
)
= 2.5V
7f
= 5V
2484 F41
N
2484 F39
225
8f
N
U
V
V
V
T
CC
REF
INCM
A
= 25°C
= 5V
= 5V
= 2.5V
2484 F37
When the LTC2484 is configured in 2x speed mode, by
performing a running average, a SINC
with the SINC
–100
–120
– 60
–20
–40
–80
Figure 38. Measured Input Normal Mode Rejection vs
Input Frequency with Input Perturbation of 150% Full
Scale (50Hz Notch)
Figure 40. Input Normal Mode Rejection 2x Speed Mode
Figure 42. Input Normal Mode Rejection 2x Speed Mode
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
–100
–120
–20
–40
–60
–80
–100
–110
–120
–130
–140
–80
–90
–70
0
4
248
48
DIFFERENTIAL INPUT SIGNAL FREQUENCY (Hz)
digital filter, yielding the normal mode
250
50
INPUT SIGNAL FREQUENCY (f
252 254 256 258 260 262 264
52
INPUT FREQUENCY (Hz)
54
NO AVERAGE
56
V
V
(150% OF FULL SCALE)
IN(P-P)
IN(P-P)
58
RUNNING
AVERAGE
WITH
= 5V
= 7.5V
N
)
60
1
2484 F40
2484 F42
notch is combined
62
V
V
V
T
A
CC
REF
IN(CM)
= 25°C
= 5V
= 5V
= 2.5V
2484 F38
2484fa