LTC1292 LINER [Linear Technology], LTC1292 Datasheet - Page 9

• Manufacturer Part Number: LTC1292
• Description: Single Chip 12-Bit Data Acquisition Systems
• Manufacturer: LINER [Linear Technology]

D
A
Microprocessor Interfaces
The LTC1292/LTC1297 can interface directly (without
external hardware) to most popular microprocessors’
(MPU) synchronous 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 LTC1292/LTC1297. Included here are
one serial interface example and one example showing a
parallel port programmed to form the serial interface.
CLK
OUT
CS
D
CLK
OUT
PPLICATI
CS
t
SMPL
RECEIVED WORD
t
suCS
t
SMPL
Hi-Z
Hi-Z
D
MPU
CLK
OUT
CS
O
B11
U
B11
B10
?
S
B10
?
B9
I FOR ATIO
U
B9
?
B8
1ST TRANSFER
B8
Figure 1. Data Exchange Between LTC1292 and MC68HC11
B7
O
t
BYTE 1
CONV
B7
t
B11
B11
CONV
W
B6
B6
B10
B10
B5
B5
B9
B4
B9
LTC1297 Operating Sequence
LTC1292 Operating Sequence
B4
B8
B8
B3
U
B3
B2
B2
B1
B7
t
CYC
B1
B0
t
CYC
B0
B7
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. A dummy D
data register starts the SPI process. With two 8-bit transfers,
the A/D result is read into the MPU (Figure 1). For the
LTC1292 the first 8-bit transfer clocks B11 through B8 of
the A/D conversion result into the processor. The second
8-bit transfer clocks the remaining bits B7 through B0 into
B1
B6
B6
B1
B2
B5
B5
B2
B3
2ND TRANSFER
B4
B4
B3
BYTE 2
B4
B3
B4
B3
B5
B2
B5
B2
B6
B6
B1
B1
B7
LTC1292/LTC1297
B7
B0
B0
B8
B8
B1
B9
POWER SHUTDOWN MODE
B9
B10
B10
B11
IN
B11
word sent to the
LTC1292/7 F01
LTC1292/7 AI01
t
LTC1292/7 AI02
SMPL
9