Datasheet

16
LTC1096/LTC1096L
LTC1098/LTC1098L
1
2 3 4
CS
CLK
DATA (D
IN
/D
OUT
) START SGL/DIFF ODD/SIGN MSBF B7 B6
•••
MSBF BIT LATCHED
BY LTC1098(L)
LTC1098(L) CONTROLS DATA LINE AND SENDS
A/D RESULT BACK TO MPU
MPU CONTROLS DATA LINE AND SENDS
MUX ADDRESS TO LTC1098(L)
PROCESSOR MUST RELEASE 
DATA LINE AFTER 4TH RISING CLK 
AND BEFORE THE 4TH FALLING CLK
LTC1098(L) TAKES CONTROL OF
DATA LINE ON 4TH FALLING CLK
LTC1-96/8 • F03
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
Figure 3. LTC1098(L) Operation with D
IN
and D
OUT
Tied Together
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 LTC1098(L) with D
IN
and D
OUT
tied to-
gether to the Intel 8051 MPU.
ACHIEVING MICROPOWER PERFORMANCE
With typical operating currents of 40µA and automatic
shutdown between conversions, the LTC1096/LTC1098
achieves extremely low power consumption over a wide
range of sample rates (see Figure 4). In systems that
convert continuously, the LTC1096/LTC1098 will draw its
normal operating power continuously. Figure 5 shows
that the typical current varies from 40µA at clock rates
below 50kHz to 100µA at 500kHz. Several things must
be taken into account to achieve such a low power
consumption.
Shutdown
Figures 1 and 2 show the operating sequence of the
LTC1096/LTC1098. The converter draws power when the
CS pin is low and powers itself down when that pin is high.
If the CS pin is not taken to ground when it is low and not
taken to supply voltage when it is high, the input buffers of
CLOCK FREQUENCY (Hz)
20
SUPPLY CURRENT, I
CC
(µA)
60
80
120
140
100 10k 100k 1M
LTC1096/98 • F05
0
1k
100
40
0.002
T
A
= 25°C
V
CC
= 5V
ACTIVE (CS LOW)
SHUTDOWN (CS HIGH)
ACTIVE AND SHUTDOWN MODES
SAMPLE FREQUENCY, f
SMPL
(kHz)
0.1
1
SUPPLY CURRENT, I
CC
(µA)
10
100
1000
1 10 100
LTC1096/98 • TPC03

T
A
= 25°C
V
CC
= V
REF
= 5V
Figure 4. Automatic Power Shutdown Between Conversions
Allows Power Consumption to Drop with Sample Rate
Figure 5. After a Conversion, When the Microprocessor
Drives CS High, the ADC Automatically Shuts Down Until the
Next Conversion. The Supply Current, Which Is Very Low
During cConversions, Drops to Zero in Shutdown