LTC1289CCN Linear Technology, LTC1289CCN Datasheet - Page 16

• Manufacturer Part Number: LTC1289CCN
• Description: IC DATA ACQ SYS 12BIT 3V 20-DIP
• Manufacturer: Linear Technology
• Type: Data Acquisition System (DAS)r

Specifications of LTC1289CCN

• Resolution (bits): 12 b
• Sampling Rate (per Second): 25k
• Data Interface: Serial, Parallel
• Voltage Supply Source: Dual ±
• Voltage - Supply: 3V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 20-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LTC1289
Figure 6 shows an example of an ideal ground plane design
for a two-sided board. Of course, this much ground plane
will not always be possible, but users should strive to get
as close to this ideal as possible.
2. Bypassing
For good performance, V
ripple. Any changes in the V
analog ground during a conversion cycle can induce
errors or noise in the output code. V
be kept below 0.5mV by bypassing the V
the analog ground plane with a 22µF tantalum capacitor
and leads as short as possible. The lead from the device to
the V
V
that obtained from a voltage regulator (e.g., LT1117).
Using a battery to power the LTC1289 will help reduce the
amount of bypass capacitance required on the V
battery placed close to the device will only require 10µF to
adequately bypass the supply pin. Figure 7 shows the
effect of poor V
of a LT1117 low dropout regulator with a 22µF bypass
16
A
CC
PPLICATI
supply should have a low output impedance such as
CC
GROUND
ANALOG
PLANE
Figure 6. Example Ground Plane for the LTC1289
supply should also be kept to a minimum and the
CC
O
bypassing. Figure 8a shows the settling
10
1
2
3
4
5
6
7
8
9
0.1µF
U
S
I FOR ATIO
CC
20
19
18
17
16
15
14
13
12
11
U
must be free of noise and
CC
V
CC
voltage with respect to
CC
22µF
TANTALUM
W
noise and ripple can
CC
V
0.1µF
CERAMIC
DISK
–
pin directly to
LTC1289 AIF06
CC
U
pin. A
capacitor. The noise and ripple is approximately 0.5mV.
Figure 8b shows the response of a lithium battery with a 10µF
bypass capacitor. The noise and ripple is kept below 0.5mV.
0.5mV/DIV
0.5mV/DIV
Figure 8a. LT1117 Regulator with 22µF Bypassing on V
5V/DIV
5V/DIV
Figure 8b. Lithium Battery with 10µF Bypassing on V
Figure 7. Poor V
Noise and Ripple Can Cause A/D Errors.
HORIZONTAL: 10µs/DIV
HORIZONTAL: 20µs/DIV
HORIZONTAL: 20µs/DIV
CC
Bypassing.
CS
CS
V
V
CC
CC
CC
CC
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