LTC1199 LINER [Linear Technology], LTC1199 Datasheet - Page 14

• Manufacturer Part Number: LTC1199
• Description: 10-Bit, 500ksps ADCs in MSOP with Auto Shutdown
• Manufacturer: LINER [Linear Technology]

LTC1197/LTC1197L
LTC1199/LTC1199L
A
Dummy Bit
The dummy bit is a placeholder that extends the acquisi-
tion time of the ADC. This bit can be either high or low and
does not affect the conversion of the ADC.
Operation with D
The LTC1199/LTC1199L can be operated with D
D
required to communicate to the microprocessor (MPU).
Data is transmitted in both directions on a single wire. The
processor pin connected to this data line should be
configurable as either an input or an output. The LTC1199/
LTC1199L will take control of the data line and drive it low
on the 4th falling CLK edge after the start bit is received
(see Figure 3). Therefore the processor port line must be
switched to an input before this happens to avoid a
conflict.
In the Typical Applications section, there is an example of
interfacing the LTC1199/LTC1199L with D
tied together to the Intel 8051 MPU.
Unipolar Transfer Curve
The LTC1197/LTC1197L/LTC1199/LTC1199L are perma-
nently configured for unipolar only. The input span and
code assignment for this conversion type are shown in the
following figures for a 5V reference.
14
OUT
DATA (D
PPLICATI
tied together. This eliminates one of the lines
IN
/D
OUT
CLK
CS
)
O
IN
U
and D
S
I FOR ATIO
OUT
U
Figure 3. LTC1199/LTC1199L Operation with D
MPU CONTROLS DATA LINE AND SENDS
MUX ADDRESS TO LTC1199/LTC1199L
Tied Together
START
1
W
SGL/DIFF
AND BEFORE THE 4TH FALLING CLK
DATA LINE AFTER 4TH RISING CLK
IN
2
and D
PROCESSOR MUST RELEASE
U
IN
and
OUT
ODD/SIGN
3
ACHIEVING MICROPOWER PERFORMANCE
With typical operating currents of 5mA (LTC1197/
LTC1199) at 5V and 0.8mA (LTC1197L/LTC1199L) at
2.7V it is possible for these ADCs to achieve true
micropower performance by taking advantage of the
automatic shutdown between conversions. In systems
1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 0
0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0
DUMMY
•
•
•
4
IN
and D
1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 0
0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0
OUTPUT CODE
OUT
•
•
LTC1199/LTC1199L TAKE CONTROL OF
DATA LINE ON 4TH FALLING CLK
NULL BITS
Tied Together
Unipolar Transfer Curve
Unipolar Output Code
LTC1199/LTC1199L CONTROL DATA LINE
AND SEND A/D RESULT BACK TO MPU
INPUT VOLTAGE
V
V
REF
REF
1LSB
0V
– 1LSB
– 2LSB
•
•
B9
INPUT VOLTAGE
(V
REF
4.99512V
4.99023V
4.88mV
= 5.000V)
0V
•
•
1197/99 AI04
B8
1197/99 F03
1197/99 AI03
V
IN