LTC1291 Linear Technology, LTC1291 Datasheet - Page 7

• Manufacturer Part Number: LTC1291
• Description: Single Chip 12-Bit Data Acquisition System
• Manufacturer: Linear Technology

The LTC1291 is a data acquisition component which
contains the following functional blocks:
1. 12-bit successive approximation capacitive A/D
2. Analog multiplexer (MUX)
3. Sample-and-hold (S/H)
4. Synchronous, half duplex serial interface
5. Control and timing logic
DIGITAL CONSIDERATIONS
Serial Interface
The LTC1291 communicates with microprocessors and
other external circuitry via a synchronous, half duplex,
four-wire serial interface (see Operating Sequence). The
clock (CLK) synchronizes the data transfer with each bit
A
TEST CIRCUITS
PPLICATI
converter
D
OUT
Voltage Waveforms for D
t
r
D
CLK
OUT
D
CS
IN
O
U
S
I FOR ATIO
OUT
U
START
Rise and Fall Times, t
1
W
t
f
2
Voltage Waveforms for t
U
1291 TC04
r
, t
2.4V
0.4V
f
3
ADDRESS IN
being transmitted on the falling CLK edge and captured on
the rising CLK edge in both transmitting and receiving
systems.
The input data is first received and then the A/D conversion
result is transmitted (half duplex). Because of the half
duplex operation D
allowing transmission over just 3 wires: CS, CLK and
CS
SHIFT MUX
D
CLK
OUT
4
D
IN
en
1
Voltage Waveforms for D
1 NULL
BIT
5
SHIFT A/D CONVERSION
RESULT OUT
D
OUT
0.8V
t
dDO
1
IN
0.8V
and D
t
Figure 1
en
OUT
OUT
D
IN
2
Delay Time, t
may be tied together
B11
1291 TC07
D
OUT
LTC1291
2
1291 TC03
dDO
2.4V
0.4V
1291 F01
7