Datasheet

27
LTC2420
Figure 31. Total Unadjusted Error at
100 Samples/Second (No Averaging)
Figure 32. Total Unadjusted Error at
7.5 Samples/Second (No Averaging)
Figure 30. Total Error vs V
REF
(Output Rate = 100sps)
APPLICATIO S I FOR ATIO
WUU
U
REFERENCE VOLTAGE (V)
1.0
TOTAL UNADJUSTED ERROR (ppm)
128
192
5.0
2420 F30
64
0
2.0
3.0
4.0
1.5
2.5
3.5
4.5
256
96
160
32
224
OUTPUT RATE = 100sps
12 BITS
13 BITS
14 BITS
15 BITS
INPUT VOLTAGE (V)
0
–40
TOTAL UNADJUSTED ERROR (ppm)
–30
–25
–20
–15
–10
–5
2420 F31
0
5
10
–35
2.5
V
CC
= 5V
V
REF
= 2.5V
INPUT VOLTAGE (V)
0
TOTAL UNADJUSTED ERROR (ppm)
–2
0
2
5
2420 F32
–4
–6
–10
–8
6
4
V
CC
= 5V
V
REF
= 5V
After acquiring 100 samples/second data the F
O
pin may
be driven LOW enabling 60Hz rejection to 110dB and the
highest possible DC accuracy. The no latency architecture
of the LTC2420 allows consecutive readings (one at 100
samples/second the next at 7.5 samples/second) without
interaction between the two readings.
As shown in Figure 33, the LTC2420 can capture transient
data with 90dB of dynamic range (with a 300mV
P-P
input
signal at 2Hz). The exceptional DC performance of the
LTC2420 enables signals to be digitized independent of a
large DC offset. Figures 34a and 34b show the dynamic
performance with a 15Hz signal superimposed on a 2V DC
level. The same signal with no DC level is shown in Figures
34c and 34d.