LTC1291BCJ8 Ver la hoja de datos (PDF) - Linear Technology
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LTC1291BCJ8 Datasheet PDF : 20 Pages
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LTC1291
APPLICATI S I FOR ATIO
Output Code
The LTC1291 performs a unipolar conversion. The follow-
ing shows the output code and transfer curve:
Unipolar Transfer Curve
Unipolar Output Code
111111111111
OUTPUT CODE
INPUT VOLTAGE
INPUT VOLTAGE (VREF = 5V)
111111111110
111111111111
111111111110
•
VREF – 1LSB
VREF – 2LSB
•
4.9988V
4.9976V
•
•
•
•
•
•
•
•
000000000001
000000000000
•
1LSB
0V
•
0.0012V
0V
000000000001
000000000000
VIN
1291 AI05a
1291 AI05b
Microprocessor Interfaces
The LTC1291 can interface directly (without external hard-
ware) to most popular microprocessors’s (MPU) synchro-
nous serial formats (see Table 1). If an MPU without a
dedicated serial port is used, then three of the MPU’s
parallel port lines can be programmed to form the serial
link to the LTC1291. Included here are one serial interface
example and one example showing a parallel port pro-
grammed to form the serial interface.
Motorola SPI (MC68HC11)
The MC68HC11 has been chosen as an example of an MPU
with a dedicated serial port. This MPU transfers data MSB
-first and in 8-bit increments. The DIN word sent to the data
register starts the SPI process. With three 8-bit transfers,
the A/D result is read into the MPU. The second 8-bit
transfer clocks B11 through B8 of the A/D conversion
result into the processor. The third 8-bit transfer clocks the
remaining bits, B7 through B0, into the MPU. The data is
right justified in the two memory locations. ANDing the
second byte with 0DHEX clears the four most significant
bits. This operation was not included in the code. It can be
inserted in the data gathering loop or outside the loop
when the data is processed.
Table 1. Microprocessor with Hardware Serial Interfaces
Compatible with the LTC1291**
PART NUMBER
TYPE OF INTERFACE
Motorola
MC6805S2, S3
SPI
MC68HC11
SPI
MC68HC05
SPI
RCA
CDP68HC05
SPI
Hitachi
HD6305
HD6301
HD63701
HD6303
HD64180
SCI Synchronous
SCI Synchronous
SCI Synchronous
SCI Synchronous
SCI Synchronous
National Semiconductor
COP400 Family
COP800 Family
NS8050U
HPC16000 Family
MICROWIRE†
MCROWIRE/PLUS†
MICROWIRE/PLUS
MICROWIRE/PLUS
Texas Instruments
TMS7002
TMS7042
TMS70C02
TMS70C42
TMS32011*
TMS32020*
TMS370C050
Serial Port
Serial Port
Serial Port
Serial Port
Serial Port
Serial Port
SPI
* Requires external hardware
** Contact LTC marketing for interface information for processors not on
this list
† MICROWIRE and MICROWIRE/PLUS are trademarks of National
Semiconductor Corporation.
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