LTC1287BCN8 Linear Technology, LTC1287BCN8 Datasheet - Page 8

• Manufacturer Part Number: LTC1287BCN8
• Description: IC DATA ACQ SYS 12BIT 3V 8-DIP
• Manufacturer: Linear Technology
• Type: Data Acquisition System (DAS)r

Specifications of LTC1287BCN8

• Resolution (bits): 12 b
• Sampling Rate (per Second): 30k
• Data Interface: Serial, Parallel
• Voltage Supply Source: Single Supply
• Voltage - Supply: 3V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LTC1287
specified at 3.3V. The output D
the above standards. The following summarizes such
levels.
The LTC1287 can be driven with 5V logic even when V
is at 3.3V. This is due to a unique input protection device
that is found on the LTC1287.
Microprocessor Interfaces
The LTC1287 can interface directly (without external hard-
ware) to most popular microprocessor (MPU) synchro-
nous serial formats. If an MPU without a serial interface is
used, then three of the MPU’s parallel port lines can be
programmed to form the serial link to the LTC1287. Many
of the popular MPUs can operate with 3V supplies. For
example the MC68HC11 is an MPU with a serial format
(SPI). Likewise parallel MPUs that have the 8051 type
architecture are also capable of operating at this voltage
range. The code for these processors remains the same
and can be found in the LTC1292 data sheet.
Sharing the Serial Interface
The LTC1287 can share the same two-wire serial interface
with other peripheral components or other LTC1287s
(Figure 2). In this case, the CS signals decide which
LTC1287 is being addressed by the MPU.
8
A
PPLICATI
OUTPUT PORT
2
SERIAL DATA
1
MPU
Figure 2. Several LTC1287s Sharing One 2-Wire Serial Interface
V
V
V
V
V
V
OH
OL
OH
OL
IH
IL
0
(no load)
(no load)
O
2
2
2 CHANNELS
LTC1287
U
S
CS
I FOR ATIO
U
V
2
OUT
2 CHANNELS
0.9 V
0.1 V
0.7 V
0.2 V
CC
LTC1287
0.1V
– 0.1V
is also compatible with
CS
W
CC
CC
CC
CC
2
2 CHANNELS
LTC1287
CS
U
2-WIRE SERIAL
INTERFACE TO OTHER
PERIPHERALS OR LTC1287s
LTC1287 F02
CC
ANALOG CONSIDERATIONS
Grounding
The LTC1287 should be used with an analog ground plane
and single point grounding techniques. Do not use wire
wrapping techniques to breadboard and evaluate the device.
To achieve the optimum performance use a PC board. The
ground pin (Pin 4) should be tied directly to the ground
plane with minimum lead length (a low profile socket is
fine). Pin 7 (V
with a 22 F (minimum value) tantalum with leads as short
as possible and as close as possible to the pin. A 0.1 F
ceramic disk also should be placed in parallel with the
22 F and again with leads as short as possible and as close
to V
LTC1287 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.
Bypassing
For good performance, V
ripple. Any changes in the V
ground during a conversion cycle can induce errors or
noise in the output code. V
below 0.5mV by bypassing the V
analog plane with a minimum of 22 F tantalum capacitor
and with leads as short as possible. The lead from the
device to the V
and the V
CC
as possible. Figure 3 shows an example of an ideal
CC
Figure 3. Example Ground Plane for the LTC1287
supply should have a low output impedance
CC
CC
) should be bypassed to the ground plane
supply also should be kept to a minimum
22 F TANTALUM
CC
1
CC
2
3
4
LTC1287
noise and ripple can be kept
must be free of noise and
CC
0.1 F
voltage with respect to
CC
8
7
6
5
V
CC
pin directly to the
LTC1287 F03
1287fa