LTC2485 LINER [Linear Technology], LTC2485 Datasheet - Page 25

• Manufacturer Part Number: LTC2485
• Description: 24-Bit ?? ADC with Easy Drive Input Current Cancellation and I2C Interface
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
current. This leakage current, nominally 1nA (±10nA max),
results in a small gain error. A 100Ω source resistance will
create a 0.05µV typical and 0.5µV maximum full-scale error.
Output Data Rate
When using its internal oscillator, the LTC2485 produces
up to 7.5 samples per second (sps) with a notch frequency
of 60Hz, 6.25sps with a notch frequency of 50Hz and
6.82sps with the 50Hz/60Hz rejection mode. The actual
output data rate will depend upon the length of the sleep
and data output phases which are controlled by the user
and which can be made insignificantly short. When oper-
ated with an external conversion clock (CA0/F
to an external oscillator), the LTC2485 output data rate can
be increased as desired. The duration of the conversion
Figure 19. –FS Error vs R
Figure 17. –FS Error vs R
–100
–300
–400
–500
–200
–10
–20
–30
–40
–50
–60
–70
–80
–90
10
0
0
0
0
V
V
V
V
T
V
V
V
V
T
A
CC
REF
IN
IN
A
CC
REF
IN
IN
= 25°C
+
–
= 25°C
C
C
+
–
= 5V
U
= 1.25V
= 3.75V
REF
= 5V
C
REF
= 5V
= 1.25V
= 3.75V
= 5V
C
REF
200
10
REF
C
= 1µF, 10µF
= 0.001µF
REF
= 0.01µF
= 100pF
SOURCE
SOURCE
= 0pF
U
100
R
400
R
SOURCE
SOURCE
at REF
at REF
(Ω)
600
(Ω)
1k
W
C
+
+
REF
C
or REF
or REF
REF
10k
800
= 0.01µF
= 0.1µF
2485 F17
2485 F19
–
–
100k
1000
(Small C
(Large C
0
U
connected
REF
REF
)
)
Figure 16. +FS Error vs R
Figure 18. +FS Error vs R
Figure 20. INL vs DIFFERENTIAL Input Voltage and Reference
Source Resistance for C
500
400
200
100
–10
300
–10
90
80
70
60
50
40
30
20
10
10
–2
–4
–6
–8
0
0
8
6
4
2
0
– 0.5
0
0
V
V
V
V
T
V
V
V
V
T
V
V
V
T
C
CC
REF
IN
IN
A
A
CC
REF
IN
IN
A
CC
REF
IN(CM)
REF
= 25°C
= 25°C
+
–
+
–
= 25°C
= 5V
= 5V
= 3.75V
= 1.25V
= 5V
= 3.75V
= 1.25V
= 5V
= 5V
C
= 5V
= 10µF
200
– 0.3
C
10
REF
C
REF
= 2.5V
REF
C
= 0.001µF
REF
= 0.01µF
= 100pF
SOURCE
SOURCE
REF
= 0pF
400
R
– 0.1
100
R
V
SOURCE
SOURCE
IN
> 1µF
/V
C
REF
REF
at REF
at REF
600
(Ω)
(Ω)
0.1
1k
(V)
= 1µF, 10µF
C
R = 500Ω
R = 100Ω
REF
+
C
+
REF
R = 1k
or REF
800
10k
or REF
0.3
= 0.01µF
= 0.1µF
LTC2485
2485 F16
2485 F18
2485 F20
1000
100k
–
–
0.5
(Small C
(Large C
25
REF
REF
2485fa
)
)