Datasheet
LTC2480
33
2480fd
applicaTions inForMaTion
OUTPUT DATA RATE (READINGS/SEC)
0
10
RESOLUTION (BITS)
12
16
18
20
24
10
50
70
2480 F23
14
22
40
90
100
20
30
60 80
V
IN(CM)
= V
REF(CM)
V
CC
= V
REF
= 5V
V
IN
= 0V
F
O
= EXT CLOCK
RES = LOG 2 (V
REF
/NOISE
RMS
)
T
A
= 85°C
T
A
= 25°C
OUTPUT DATA RATE (READINGS/SEC)
0
10
RESOLUTION (BITS)
12
16
18
22
10
50
70
2480 F24
14
20
40
90
100
20
30
60 80
T
A
= 85°C
T
A
= 25°C
V
IN(CM)
= V
REF(CM)
V
CC
= V
REF
= 5V
F
O
= EXT CLOCK
RES = LOG 2 (V
REF
/INL
MAX
)
OUTPUT DATA RATE (READINGS/SEC)
0
–10
OFFSET ERROR (ppm OF V
REF
)
–5
5
10
20
10
50
70
2480 F25
0
15
40
90
100
20
30
60 80
V
CC
= 5V, V
REF
= 2.5V
V
CC
= V
REF
= 5V
V
IN(CM)
= V
REF(CM)
V
IN
= 0V
F
O
= EXT CLOCK
T
A
= 25°C
Figure 23. Resolution (Noise
RMS
≤ 1LSB)
vs Output Data Rate and Temperature
Figure 24. Resolution (INL
MAX
≤ 1LSB)
vs Output Data Rate and Temperature
Figure 25. Offset Error vs Output
Data Rate and Reference Voltage
Figure 26. Resolution (Noise
RMS
≤ 1LSB)
vs Output Data Rate and Reference Voltage
Figure 27. Resolution (INL
MAX
≤ 1LSB)
vs Output Data Rate and Reference Voltage
OUTPUT DATA RATE (READINGS/SEC)
0
10
RESOLUTION (BITS)
12
16
18
20
24
10
50
70
2480 F26
14
22
40
90
100
20
30
60 80
V
IN(CM)
= V
REF(CM)
V
IN
= 0V
F
O
= EXT CLOCK
T
A
= 25°C
RES = LOG 2 (V
REF
/NOISE
RMS
)
V
CC
= 5V, V
REF
= 2.5V
V
CC
= V
REF
= 5V
OUTPUT DATA RATE (READINGS/SEC)
0
10
RESOLUTION (BITS)
12
16
18
22
10
50
70
2480 F27
14
20
40
90
100
20
30
60 80
V
CC
= 5V, V
REF
= 2.5V
V
CC
= V
REF
= 5V
V
IN(CM)
= V
REF(CM)
V
IN
= 0V
REF
–
= GND
F
O
= EXT CLOCK
T
A
= 25°C
RES = LOG 2 (V
REF
/INL
MAX
)
quency. In many applications, the subsequent performance
degradation can be substantially reduced by relying upon
the LTC2480’s exceptional common 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
+
and IN
–
pins.
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
IN
, C
REF
) are used, the
previous section provides formulae for evaluating the effect
of the source resistance upon the converter performance for
any value of
fEOSC
. If small external input and/or reference
capacitors (C
IN
, C
REF
) are used, the effect of the external
source resistance upon the LTC2480 typical performance
can be inferred from Figures 13, 14, 15 and 16 in which
the horizontal axis is scaled by 307200/f
EOSC
.
Third, an increase in the frequency of the external oscillator
above 1MHz (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 20 to 27. In
order to obtain the highest possible level of accuracy from
this converter at output data rates above 20 readings per