LTC1290BI LINER [Linear Technology], LTC1290BI Datasheet - Page 14

• Manufacturer Part Number: LTC1290BI
• Description: Single Chip 12-Bit Data Acquisition System
• Manufacturer: LINER [Linear Technology]

LTC1290
Microprocessor Interfaces
The LTC1290 can interface directly (without external hard-
ware) to most popular microprocessor (MPU) synchro-
nous serial formats (see Table 2). If an MPU without a
serial interface is used, then four of the MPU’s parallel port
lines can be programmed to form the serial link to the
LTC1290. Included here are two serial interface examples
and one example showing a parallel port programmed to
form the serial interface
14
A
PPLICATI
SCLK
D
SCLK
D
OUT
D
OUT
CS
D
CS
IN
IN
Figure 4. CS Low During Conversion (CS Must go High to Low Once to Insure Proper Operation in this Mode)
B11 B10 B9
B11 B10 B9
MUX ADDRESS
MUX ADDRESS
O
SHIFT
SHIFT
IN
IN
U
S
B8
B8
I FOR ATIO
B7
B7
U
B6
B6
B5
B5
SAMPLE ANALOG
SAMPLE ANALOG
W
B4
B4
INPUT
t
INPUT
t
SMPL
SMPL
B3
B3
Figure 3. CS High During Conversion
B2
B2
DON’T CARE
DON’T CARE
B1
B1
U
B0
B0
REMAIN LOW
ACLK CYC
SCLK MUST
ACLK CYC
48 TO 52
48 TO 52
Serial Port Microprocessors
Most synchronous serial formats contain a shift clock
(SCLK) and two data lines, one for transmitting and one for
receiving. In most cases data bits are transmitted on the
falling edge of the clock (SCLK) and captured on the rising
edge. However, serial port formats vary among MPU
manufactures as to the smallest number of bits that can be
sent in one group (e.g., 4-bit, 8-bit or 16-bit transfers).
They also vary as to the order in which the bits are
transmitted (LSB or MSB first). The following examples
show how the LTC1290 accommodates these differences.
B11 B10 B9 B8
B11 B10 B9
B8
AND NEW ADDRESS IN
AND NEW ADDRESS IN
SHIFT RESULT OUT
B7
SHIFT RESULT OUT
B7
B6
B6
B5
B5
B4
B4
B3
B3
B2
B2
B1
B1 B0
B0
LTC1290 F04
LTC1290 F03