LTC1293/LTC1294/LTC1296
Single Chip 12-Bit
Data Acquisition System
FEATURES
s
DESCRIPTIO
s
s
s
s
s
Software Programmable Features
Unipolar/Bipolar Conversion
Differential/Single Ended Inputs
MSB-First or MSB/LSB Data Sequence
Power Shutdown
Built-In Sample and Hold
Single Supply 5V or
±5V
Operation
Direct 4-Wire Interface to Most MPU Serial
Ports and All MPU Parallel Ports
46.5kHz Maximum Throughput Rate
System Shutdown Output (LTC1296)
The LTC1293/4/6 is a family of data acquisition systems
which contain a serial I/O successive approximation A/D
converter. It uses LTCMOS
TM
switched capacitor technol-
ogy to perform either 12-bit unipolar, or 11-bit plus sign
bipolar A/D conversions. The input multiplexer can be
configured for either single ended or differential inputs (or
combinations thereof). An on-chip sample and hold is
included for all single ended input channels. When the
LTC1293/4/6 is idle it can be powered down in applica-
tions where low power consumption is desired. The
LTC1296 includes a System Shutdown Output pin which
can be used to power down external circuitry, such as
signal conditioning circuitry prior to the input mux.
The serial I/O is designed to communicate without external
hardware to most MPU serial ports and all MPU parallel
I/O ports allowing up to eight channels of data to be
transmitted over as few as three wires.
LTCMOS
TM
is a trademark of Linear Technology Corporation
KEY SPECIFICATIO S
s
s
s
Resolution ..................................................... 12 Bits
Fast Conversion Time ............ 12µs Max Over Temp.
Low Supply Current ........................................ 6.0mA
TYPICAL APPLICATI
12-Bit Data Acquisition System with Power Shutdown
R
B
5.1k
2N3906
+
R1
10k
1/4 LT1014
R2
1.2M
CH0
CH1
CH2
CH3
V
CC
SSO
CLK
CS
–
R2
1.2M
C2
1µF
350Ω STRAIN
GAUGE BRIDGE
CH4
CH5
CH6
CH7
COM
LTC1296
D
OUT
D
IN
REF
+
REF
–
AGND
V
–
THREE ADDITIONAL STRAIN GAUGE INPUTS
CAN BE ACCOMMODATED USING THE OTHER
AMPLIFIERS IN THE LT1014
DGND
U
74HC04
47µF
+5V
MPU
1N4148
LTC1293 TA01
UO
U
1
LTC1293/LTC1294/LTC1296
ABSOLUTE
AXI U
RATI GS
(Note 1 and 2)
Operating Temperature Range
LTC1293/4/6BC, LTC1293/4/6CC,
LTC1293/4/6DC ....................................... 0°C to 70°C
LTC1293/4/6BI, LTC1293/4/6CI,
LTC1293/4/6DI .................................... –40°C to 85°C
LTC1293/4/6BM, LTC1293/4/6CM,
LTC1293/4/6DM ............................... –55°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec.)................ 300°C
Supply Voltage (V
CC
) to GND or V
–
...................................................
12V
Negative Supply Voltage (V
–
) ..................... –6V to GND
Voltage
Analog and Reference
Inputs ............................ (V
–
) –0.3V to V
CC
+ 0.3V
Digital Inputs ......................................... –0.3V to 12V
Digital Outputs........................... –0.3V to V
CC
+ 0.3V
Power Dissipation............................................. 500mW
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CH0
CH1
CH2
CH3
CH4
CH5
COM
DGND
1
2
3
4
5
6
7
8
S PACKAGE
16-LEAD PLASTIC SOL
TOP VIEW
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
1
2
3
4
5
6
7
8
9
20 DV
CC
19 AV
CC
18 CLK
17 CS
16 D
OUT
15 D
IN
14 REF
+
16 V
CC
15 CLK
14 CS
13 D
OUT
12 D
IN
11 V
REF
10 AGND
9
V
–
ORDER PART
NUMBER
LTC1293BCS
LTC1293CCS
LTC1293DCS
LTC1294BCS
LTC1294CCS
LTC1294DCS
13 REF
–
12 AGND
11 V
–
S PACKAGE
20-LEAD PLASTIC SO
DGND 10
J PACKAGE
20-LEAD CERAMIC DIP
TOP VIEW
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
1
2
3
4
5
6
7
8
9
20 V
CC
19 SSO
18 CLK
17 CS
16 D
OUT
15 D
IN
14 REF
+
LTC1296BCS
LTC1296CCS
LTC1296DCS
13 REF
–
12 AGND
11 V
S PACKAGE
20-LEAD PLASTIC SO
–
DGND 10
J PACKAGE
20-LEAD CERAMIC DIP
2
U
U
W
W W
U
W
TOP VIEW
CH0
CH1
CH2
CH3
CH4
CH5
COM
DGND
1
2
3
4
5
6
7
8
16 V
CC
15 CLK
14 CS
13 D
OUT
12 D
IN
11 V
REF
10 AGND
9
V
–
ORDER PART
NUMBER
LTC1293BMJ
LTC1293CMJ
LTC1293DMJ
LTC1293BIJ
LTC1293CIJ
LTC1293DIJ
LTC1293BIN
LTC1293CIN
LTC1293DIN
LTC1293BCN
LTC1293CCN
LTC1293DCN
J PACKAGE
N PACKAGE
16-LEAD CERAMIC DIP 16-LEAD PLASTIC DIP
TOP VIEW
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
1
2
3
4
5
6
7
8
9
20 DV
CC
19 AV
CC
18 CLK
17 CS
16 D
OUT
15 D
IN
14 REF
+
13 REF
–
12 AGND
11 V
–
N PACKAGE
20-LEAD PLASTIC DIP
LTC1294BMJ
LTC1294CMJ
LTC1294DMJ
LTC1294BIJ
LTC1294CIJ
LTC1294DIJ
LTC1294BIN
LTC1294CIN
LTC1294DIN
LTC1294BCN
LTC1294CCN
LTC1294DCN
DGND 10
TOP VIEW
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
1
2
3
4
5
6
7
8
9
20 V
CC
19 SSO
18 CLK
17 CS
16 D
OUT
15 D
IN
14 REF
+
13 REF
–
12 AGND
11 V
–
N PACKAGE
20-LEAD PLASTIC DIP
LTC1296BMJ
LTC1296CMJ
LTC1296DMJ
LTC1296BIJ
LTC1296CIJ
LTC1296DIJ
LTC1296BIN
LTC1296CIN
LTC1296DIN
LTC1296BCN
LTC1296CCN
LTC1296DCN
DGND 10
LTC1293/LTC1294/LTC1296
CO VERTER A D
PARAMETER
Offset Error
Linearity Error (INL)
Gain Error
Minimum Resolution for which No
Missing Codes are Guaranteed
Analog and REF Input Range
On Channel Leakage Current (Note 8)
Off Channel Lekage Current (Note 8)
AC CHARACTERISTICS
(Note 3)
SYMBOL
f
CLK
t
SMPL
t
CONV
t
CYC
t
dDO
t
dis
t
en
t
hDI
t
hDO
t
f
t
r
t
WHCLK
t
WLCLK
t
suDI
t
suCS
t
wHCS
t
wLCS
t
enSSO
t
disSSO
C
IN
PARAMETER
Clock Frequency
Analog Input Sample Time
Conversion Time
Total Cycle Time
Delay Time, CLK↓ to D
OUT
Data Valid
Delay Time, CS↑ to D
OUT
Hi-Z
Delay Time, CLK↓ to D
OUT
Enabled
Hold Time, D
IN
after CLK↑
Time Output Data Remains Valid After CLK↓
D
OUT
Fall Time
D
OUT
Rise Time
CLK High Time
CLK Low Time
Set-up Time, D
IN
Stable Before CLK↑
Set-up Time, CS↓ before CLK↑
CS High Time During Conversion
CS Low Time During Data Transfer
Delay Time, CLK↓ to SSO↓
Delay Time, CS↓ to SSO↑
Input Capacitance
See Test Circuits
See Test Circuits
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
See Test Circuits
See Test Circuits
Analog Inputs On Channel
Analog Inputs Off Channel
Digital Inputs
q
q
q
q
W U
U
ULTIPLEXER CHARACTERISTICS
(Note 3)
LTC1293/4/6B
LTC1293/4/6C
MIN
TYP MAX
±3.0
±0.5
±1.0
12
(V
–
)–0.05V to V
CC
+ 0.05V
q
q
q
q
LTC1293/4/6D
MIN
TYP MAX
±3.0
±0.75
±4.0
12
UNITS
LSB
LSB
LSB
Bits
V
±1
±1
±1
±1
µA
µA
µA
µA
CONDITIONS
(Note 4)
(Notes 4, 5)
(Note 4)
q
q
q
q
MIN
TYP MAX
±3.0
±0.5
±0.5
12
(Note 7)
On Channel = 5V
Off Channel = 0V
On Channel = 0V
Off Channel = 5V
On Channel = 5V
Off Channel = 0V
On Channel = 0V
Off Channel = 5V
±1
±1
±1
±1
±1
±1
±1
±1
CONDITIONS
V
CC
= 5V (Note 6)
See Operating Sequence
See Operating Sequence
See Operating Sequence (Note 6)
See Test Circuits
See Test Circuits
See Test Circuits
V
CC
= 5V (Note 6)
q
q
q
LTC1293/4/6B
LTC1293/4/6C
LTC1293/4/6D
MIN
TYP
MAX
0.1
2.5
12
21 CLK
+500ns
160
80
80
50
130
65
25
300
400
50
50
500
21
750
250
100
5
5
1500
500
130
50
300
150
200
1.0
UNITS
MHz
CLK Cycles
CLK Cycles
Cycles
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
CLK Cycles
ns
ns
pF
3
LTC1293/LTC1294/LTC1296
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
(Note 3)
SYMBOL
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
I
OZ
I
SOURCE
I
SINK
I
CC
I
CC
PARAMETER
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
High Level Output Voltage
Low Level Output Voltage
High Z Output Leakage
Output Source Current
Output Sink Current
Positive Supply Current
Positive Supply Current
CONDITIONS
V
CC
= 5.25V
V
CC
= 4.75V
V
IN
= V
CC
V
IN
= 0V
V
CC
= 4.75V, I
O
= –10mA
I
O
= 360µA
V
CC
= 4.75V, I
O
= 1.6mA
V
OUT =
V
CC
, CS High
V
OUT
= 0V, CS High
V
OUT
= 0V
V
OUT
= V
CC
CS High
CS High,
Power
Shutdown
CLK Off
I
REF
I
–
I
SOURCEs
I
SINKs
Reference Current
Negative Supply Current
SSO Source Current
SSO Sink Current
CS High
CS High
V
SSO
= 0V
V
SSO
= V
CC
LTC1294BC, LTC1294CC,
LTC1294DC, LTC1294BI,
LTC1294CI, LTC1294DI,
LTC1294BM, LTC1294CM,
LTC1294DM
q
q
q
q
q
q
q
q
q
q
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
All voltage values are with respect to DGND, AGND and REF
–
wired
together (unless otherwise noted).
Note 3:
V
CC
= 5V, V
REF+
= 5V, V
REF
–
= 0V, V
–
= 0V for unipolar mode and
–5V for bipolar mode, CLK = 1.0MHz unless otherwise specified. The
q
denotes specifications which apply over the full operating temperature
range; all other limits and typicals T
A
= 25°C.
Note 4:
These specs apply for both unipolar and bipolar modes. In bipolar
mode, one LSB is equal to the bipolar input span (2V
REF
) divided by 4096.
For example, when V
REF
= 5V, 1LSB (bipolar) = 2 (5V)/4096 = 2.44mV.
Note 5:
Linearity error is specified between the actual end points of the
A/D transfer curve. The deviation is measured from the center of the
quantization band.
4
U
LTC1293/4/6B
LTC1293/4/6C
LTC1293/4/6D
MIN
TYP
MAX
2.0
0.8
2.5
–2.5
2.4
4.7
4.0
0.4
3
–3
–20
20
6
5
12
10
UNITS
V
V
µA
µA
V
V
µA
mA
mA
mA
µA
q
q
q
q
q
5
10
1
0.8
0.5
1.5
1.0
15
50
50
µA
µA
µA
mA
mA
Note 6:
Recommended operating conditions.
Note 7:
Two on-chip diodes are tied to each reference and analog input
which will conduct for reference or analog input voltages one diode drop
below V
–
or one diode drop above V
CC
. Be careful during testing at low
V
CC
levels (4.5V), as high level reference or analog inputs (5V) can cause
this input diode to conduct, especially at elevated temperatures, and cause
errors for inputs near full scale. This spec allows 50mV forward bias of
either diode. This means that as long as the reference or analog input
does not exceed the supply voltage by more than 50mV, the output code
will be correct. To achieve an absolute 0V to 5V input voltage range will
therefore require a minimum supply voltage of 4.950V over initial
tolerance, temperature variations and loading.
Note 8:
Channel leakage current is measured after the channel selection.
LTC1293/LTC1294/LTC1296
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
10
CLK = 1MHz
T
A
= 25°C
8
OFFSET (LSB = 1/4096
×
V
REF
)
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
6
4
2
0
4
5
SUPPLY VOLTAGE (V)
Change in Linearity vs Reference
Voltage
CHANGE IN LINEARITY (LSB = 1/4096
×
V
REF
)
1.25
CHANGE IN GAIN (LSB = 1/4096
×
V
REF
)
1.00
–0.2
–0.4
–0.6
–0.8
–1.0
–1.2
MAGNITUDE OF OFFSET CHANGE (LSB)
0.75
0.50
0.25
0
0
1
3
4
2
REFERENCE VOLTAGE (V)
Change in Linearity vs
Temperature
0.5
MAGNITUDE OF LINEARITY CHANGE (LSB)
MAGNITUDE OF GAIN CHANGE (LSB)
0.5
MINIMUM CLK FREQUENCY* (MHz)
0.4
V
CC
= 5V
V
REF
= 5V
CLK = 1MHz
0.3
0.2
0.1
0
–50
–25
25
50
75 100
0
AMBIENT TEMPERATURE (°C)
U W
6
LTC1293 G01
Supply Current vs Temperature
10
9
8
7
6
5
4
3
–50 –30 –10 10 30 50 70 90 110 130
AMBIENT TEMPERATURE (°C)
LTC1293 G02
Unadjusted Offset Voltage vs
Reference Voltage
0.9
V
CC
= 5V
0.8
0.7
0.6
0.5
0.4
V
OS
= 0.250mV
0.3
0.2
0.1
1
V
OS
= 0.125mV
3
2
4
REFERENCE VOLTAGE (V)
5
LTC1293 G03
CLK = 1MHz
V
CC
= 5V
Change in Gain vs Reference
Voltage
0
V
CC
= 5V
Change in Offset vs Temperature
0.5
V
CC
= 5V
V
REF
= 5V
CLK = 1MHz
0.4
LTC1294/6
0.3
0.2
0.1
LTC1293
0
1
2
3
4
REFERENCE VOLTAGE (V)
5
LTC1293 G05
5
LTC1293 G04
0
–50
–25
25
50
75 100
0
AMBIENT TEMPERATURE (°C)
125
LTC1293 G06
Change in Gain vs Temperature
V
CC
= 5V
V
REF
= 5V
CLK = 1MHz
Minimum Clock Rate for 0.1LSB
Error
V
CC
= 5V
0.25
0.20
0.15
0.10
0.05
0.4
0.3
0.2
0.1
125
0
–50
–25
25
50
75 100
0
AMBIENT TEMPERATURE (°C)
125
–50
–25
25
50
75 100
0
AMBIENT TEMPERATURE (°C)
125
LTC1293 G07
LTC1293 G08
LTC1293 G09
* AS THE CLK FREQUENCY IS DECREASED FROM 1MHz, MINIMUM CLK FREQUENCY (∆ERROR
≤
0.1LSB) REPRESENTS
THE FREQUENCY AT WHICH A 0.1LSB SHIFT IN ANY CODE TRANSITION FROM ITS 1MHz VALUE IS FIRST DETECTED.
5
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