LTC1865 LINER [Linear Technology], LTC1865 Datasheet - Page 16

• Manufacturer Part Number: LTC1865
• Description: Ultra-Tiny, Differential, 16-Bit ADC with SPI Interface SPI Interface
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
LTC2452
Figure 17 shows the measured LTC2452 INL vs Input
Voltage as a function of R
C
In some cases, R
The input current is zero when the ADC is either in sleep
or I/O modes. Thus, if the time constant of the input RC
circuit t = R
longer than the time periods between actual conversions,
then one can consider the input current to be reduced
correspondingly.
These considerations need to be balanced out by the input
signal bandwidth. The 3dB bandwidth ≈ 1/(2pR
16
IN
= 0.1µF .
Figure 17. Measured INL vs Input Voltage,
C
–10
10
–2
–4
–6
–8
IN
S
8
6
4
2
0
–5
= 0.1µF , V
• C
C
V
T
A
IN
CC
R
–4
S
= 25°C
S
IN
= 0.1µF
= 5V
can be increased above these guidelines.
DIFFERENTIAL INPUT VOLTAGE (V)
= 1k
, is of the same order of magnitude or
–3
R
S
–2
CC
= 2k
R
S
= 5V, T
–1
R
= 0
S
S
= 10k
value with an input capacitor
0
A
1
= 25°C
2
3
4
2452 F17
5
S
C
IN
).
Finally, if the recommended choice for C
for the user’s specific application, an alternate strategy is to
eliminate C
this configuration corresponds to a low impedance sensor
directly connected to the ADC through minimum length
traces. Actual applications include current measurements
through low value sense resistors, temperature measure-
ments, low impedance voltage source monitoring, and so
on. The resultant INL vs V
measurements of Figure 18 include a capacitor C
responding to a minimum sized layout pad and a minimum
width input trace of about 1 inch length.
–10
Figure 18. Measured INL vs Input Voltage,
C
10
–2
–4
–6
–8
IN
IN
8
6
4
2
0
–5
and minimize C
= 0, V
C
V
T
IN
CC
A
–4
= 25°C
= 0
= 5V
R
DIFFERENTIAL INPUT VOLTAGE (V)
S
R
–3
CC
R
S
= 1k, 2k
S
= 10k
= 0
= 5V, T
–2
–1
A
IN
0
PAR
= 25°C
is shown in Figure 18. The
1
and R
2
3
S
. In practical terms,
IN
4
2452 F18
is unacceptable
5
PAR
cor-
2452fc