LTC1096 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1096' PDF : 28 Pages View PDF
APPLICATIONS INFORMATION
CS
1
2
CLK
LTC1096/LTC1096L
LTC1098/LTC1098L
MSBF BIT LATCHED
BY LTC1098(L)
3
4
DATA (DIN/DOUT)
START
SGL/DIFF
ODD/SIGN
MSBF
B7
B6
•••
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) CONTROLS DATA LINE AND SENDS
A/D RESULT BACK TO MPU
LTC1098(L) TAKES CONTROL OF
DATA LINE ON 4TH FALLING CLK
Figure 3. LTC1098(L) Operation with DIN and DOUT Tied Together
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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 LTC1098(L) with DIN and DOUT tied together
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
1000
TA = 25°C
VCC = 5V
100
10
1
0.1
1
10
Sample Rate, fSAMPLE (kHz)
100
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Figure 4. Automatic Power Shutdown Between Conversions
Allows Power Consumption to Drop with Sample Rate
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.
SUPPLY CURRENT vs CLOCK RATE FOR
ACTIVE AND SHUTDOWN MODES
140
TA = 25°C
120 VCC = 5V
100
80
60
ACTIVE (CS LOW)
40
20
0.002
SHUTDOWN (CS HIGH)
0
100
1k
10k
100k
1M
CLOCK FREQUENCY (Hz)
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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
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
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