LTC1290
Single Chip 12-Bit Data
Acquisition System
FEATURES
s
DESCRIPTIO
s
s
s
s
Software Programmable Features
– Unipolar/Bipolar Conversion
– Four Differential/Eight Single-Ended Inputs
– MSB- or LSB-First Data Sequence
– Variable Data Word Length
– Power Shutdown
Built-In Sample-and-Hold
Single Supply 5V or
±5V
Operation
Direct Four-Wire Interface to Most MPU Serial Ports
and All MPU Parallel Ports
50kHz Maximum Throughput Rate
The LTC
®
1290 is a data acquisition component which
contains a serial I/O successive approximation A/D con-
verter. It uses LTCMOS
TM
switched capacitor technology
to perform either 12-bit unipolar or 11-bit plus sign bipolar
A/D conversions. The 8-channel 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
LTC1290 is idle it can be powered down with a serial word
in applications where low power consumption is desired.
The serial I/O is designed to be compatible with industry
standard full duplex serial interfaces. It allows either MSB-
or LSB-first data and automatically provides 2's comple-
ment output coding in the bipolar mode. The output data
word can be programmed for a length of 8, 12 or 16 bits.
This allows easy interface to shift registers and a variety of
processors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTCMOS is a trademark of Linear Technology Corporation.
KEY SPECIFICATIO S
s
s
s
Resolution: 12 Bits
Fast Conversion Time: 13µs Max Over Temp
Low Supply Current: 6.0mA
TYPICAL APPLICATI
SINGLE-ENDED INPUT
0V TO 5V OR
±5V
±15V
OVERVOLTAGE RANGE*
12-Bit 8-Channel Sampling Data Acquisition System
1k
CH0
CH1
CH2
CH3
DIFFERENTIAL INPUT (+)
±5V
COMMON MODE RANGE (–)
CH4
CH5
LTC1290
V
CC
ACLK
SCLK
D
IN
D
OUT
CS
REF
+
REF
–
V
–
•
•
•
+
22µF
TANTALUM
1N5817
TO AND FROM
MICROPROCESSOR
•
•
•
CH6
CH7
COM
DGND
+
4.7µF
TANTALUM
–5V
1N5817
0.1µF
AGND
* FOR OVERVOLTAGE PROTECTION ON ONLY ONE CHANNEL LIMIT THE INPUT CURRENT TO 15mA. FOR OVERVOLTAGE PROTECTION
ON MORE THAN ONE CHANNEL LIMIT THE INPUT CURRENT TO 7mA PER CHANNEL AND 28mA FOR ALL CHANNELS. (SEE SECTION ON
OVERVOLTAGE PROTECTION IN THE APPLICATIONS INFORMATION SECTION.) CONVERSION RESULTS ARE NOT VALID WHEN THE SELECTED
OR ANY OTHER CHANNEL IS OVERVOLTAGED (V
IN
< V
–
OR V
IN
> V
CC
).
U
5V
1N4148
LT
®
1027
8V TO 40V
1µF
1290 • TA01
UO
U
1
LTC1290
ABSOLUTE
AXI U
RATI GS
(Notes 1, 2)
Operating Temperature Range
LTC1290BC, LTC1290CC, LTC1290DC .... 0°C to 70°C
LTC1290BI, LTC1290CI, LTC1290DI .... – 40°C to 85°C
LTC1290BM, LTC1290CM,
LTC1290DM....................................... – 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/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
CH6
CH7
COM
1
2
3
4
5
6
7
8
9
20 V
CC
19 ACLK
18 SCLK
17 D
IN
16 D
OUT
15 CS
14 REF
+
13 REF
–
12
V
–
ORDER PART
NUMBER
LTC1290BMJ
LTC1290CMJ
LTC1290DMJ
LTC1290BIJ
LTC1290CIJ
LTC1290DIJ
LTC1290BIN
LTC1290CIN
LTC1290DIN
LTC1290BCN
LTC1290CCN
LTC1290DCN
CH0 1
CH1 2
CH2 3
CH3 4
CH4 5
CH5 6
CH6 7
CH7 8
COM 9
DGND 10
DGND 10
J PACKAGE
20-LEAD CERAMIC DIP
11 AGND
N PACKAGE
20-LEAD PDIP
T
JMAX
= 150°C,
θ
JA
= 80°C/W (J)
T
JMAX
= 110°C,
θ
JA
= 100°C/W (N)
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)
ULTIPLEXER CHARACTERISTICS
MIN
q
q
q
q
CONDITIONS
(Note 4)
(Notes 4,5)
(Note 4)
LTC1290B
TYP
MAX
±1.5
±0.5
±0.5
12
(Note 7)
On Channel = 5V
Off Channel = 0V
On Channel = 0V
Off Channel = 5V
q
q
q
q
(V
–
) – 0.05V to V
CC
+ 0.05V (V
–
) – 0.05V to V
CC
+ 0.05V (V
–
) – 0.05V to V
CC
+ 0.05V
±1
±1
±1
±1
±1
±1
±1
±1
±1
±1
±1
±1
Off Channel Leakage Current
(Note 8)
On Channel = 5V
Off Channel = 0V
On Channel = 0V
Off Channel = 5V
2
U
U
W
W W
U
W U
W
TOP VIEW
20 V
CC
19 ACLK
18 SCLK
17 D
IN
16 D
OUT
15 CS
14 REF
+
13 REF
–
12 V
–
11 AGND
ORDER PART
NUMBER
LTC1290BCSW
LTC1290CCSW
LTC1290DCSW
LTC1290BISW
LTC1290CISW
LTC1290DISW
SW PACKAGE
20-LEAD PLASTIC SO WIDE
T
JMAX
= 110°C,
θ
JA
= 130°C/W (SW)
U
(Note 3)
MIN
LTC1290D
TYP
MAX
±1.5
±0.75
±4.0
12
UNITS
LSB
LSB
LSB
Bits
V
µA
µA
µA
µA
MIN
LTC1290C
TYP
MAX
±1.5
±0.5
±1.0
12
LTC1290
AC CHARACTERISTICS
SYMBOL
f
SCLK
f
ACLK
t
ACC
t
SMPL
t
CONV
t
CYC
t
dDO
PARAMETER
Shift Clock Frequency
A/D Clock Frequency
Delay time from CS↓ to D
OUT
Data Valid
Analog Input Sample Time
Conversion Time
Total Cycle Time
Delay Time, SCLK↓ to D
OUT
Data Valid
(Note 3)
CONDITIONS
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
(Note 9)
See Operating Sequence
See Operating Sequence
See Operating Sequence (Note 6)
See Test Circuits LTC1290BC, LTC1290CC
LTC1290DC, LTC1290BI
LTC1290CI, LTC1290DI
q
LTC1290B/LTC1290C/LTC1290D
MIN
TYP
MAX
0
(Note 10)
2
7
52
12 SCLK +
56 ACLK
130
220
2.0
4.0
UNITS
MHz
MHz
ACLK
Cycles
SCLK
Cycles
ACLK
Cycles
Cycles
ns
LTC1290BM, LTC1290CM
q
LTC1290DM
t
dis
t
en
t
hCS
t
hDI
t
hDO
t
f
t
r
t
suDI
t
suCS
t
WHCS
C
IN
Delay Time, CS↑ to D
OUT
Hi-Z
Delay Time, 2nd ACLK↓ to D
OUT
Enabled
Hold Time, CS After Last SCLK↓
Hold Time, D
IN
After SCLK↑
Time Output Data Remains Valid After SCLK↓
D
OUT
Fall Time
D
OUT
Rise Time
Setup Time, D
IN
Stable Before SCLK↑
Setup Time, CS↓ Before Clocking in
First Address Bit
CS High Time During Conversion
Input Capacitance
See Test Circuits
See Test Circuits
V
CC
= 5V (Note 6)
(Notes 6, 9)
V
CC
= 5V (Note 6)
Analog Inputs On Channel
Analog Inputs Off Channel
Digital Inputs
q
q
180
70
130
0
50
50
65
25
50
2 ACLK Cycles
+ 100ns
52
100
5
5
270
100
200
ns
ns
ns
ns
ns
ns
See Test Circuits
See Test Circuits
V
CC
= 5V (Note 6)
V
CC
= 5V (Note 6)
q
q
130
50
ns
ns
ns
ACLK
Cycles
pF
pF
pF
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
SYMBOL
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
I
OZ
I
SOURCE
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
CONDITIONS
V
CC
= 5.25V
V
CC
= 4.75V
V
IN
= V
CC
V
IN
= 0V
V
CC
= 4.75V I
O
= 10µA
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
U
(Note 3)
LTC1290B/LTC1290C/LTC1290D
MIN
TYP MAX
q
q
q
q
q
q
q
q
UNITS
V
V
µA
µA
V
V
2.0
0.8
2.5
– 2.5
2.4
4.7
4.0
0.4
3
–3
–20
V
µA
µA
mA
3
LTC1290
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
SYMBOL
I
SINK
I
CC
PARAMETER
Output Sink Current
Positive Supply Current
CONDITIONS
V
OUT
= V
CC
CS High
CS High
LTC1290BC, LTC1290CC
Power Shutdown LTC1290DC, LTC1290BI
ACLK Off
LTC1290CI, LTC1290DI
q
q
I
REF
I
–
Reference Current
Negative Supply Current
The
q
denotes specifications which apply over the full operating
temperature range; all other limits and typicals T
A
= 25°C.
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 ground with 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, ACLK = 4.0MHz unless otherwise speicfied.
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:
Integral nonlinearity is defined as the deviation of a code from a
straight line passing through the actual endpoints of the transfer curve.
The deviation is measured from the center of the quantization band.
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
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
26
22
18
14
10
6
2
4
6
8
SUPPLY VOLTAGE, V
CC
(V)
10
1290 • TPC01
9
OFFSET ERROR (LSB = 1 • V
REF
)
4096
ACLK = 4MHz
T
A
= 25°C
SUPPLY CURRENT, I
CC
(mA)
SUPPLY CURRENT, I
CC
(mA)
4
U W
U
(Note 3)
LTC1290B/LTC1290C/LTC1290D
MIN
TYP
MAX
20
6
5
12
10
UNITS
mA
mA
µA
LTC1290BM, LTC1290CM
q
LTC1290DM
V
REF
= 5V
CS High
q
q
5
10
1
15
50
50
µA
µA
µA
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.
Note 9:
To minimize errors caused by noise at the chip select input, the
internal circuitry waits for two ACLK falling edge after a chip select falling
edge is detected before responding to control input signals. Therefore, no
attempt should be made to clock an address in or data out until the
minimum chip select setup time has elapsed.
Note 10:
Increased leakage currents at elevated temperatures cause the
S/H to droop, therefore it's recommended that f
ACLK
≥
500kHz at 125°C,
f
ACLK
≥
125kHz at 85°C and f
ACLK
≥
15kHz at 25°C.
Supply Current vs Temperature
10
ACLK = 4MHz
V
CC
= 5V
Unadjusted Offset Voltage vs
Reference Voltage
0.9
V
CC
= 5V
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
1
3
2
4
REFERENCE VOLTAGE, V
REF
(V)
5
V
OS
= 0.125mV
V
OS
= 0.25mV
8
7
6
5
4
3
–50 –30 –10 10 30 50 70 90 110 130
AMBIENT TEMPERATURE, T
A
(°C)
LT1290 • TPC02
1290 • TPC03
LTC1290
TYPICAL PERFOR A CE CHARACTERISTICS
Change in Linearity vs Reference
Voltage
LINEARITY ERROR (LSB = 1 • V
REF
)
4096
V
CC
= 5V
1.00
CHANGE IN GAIN ERROR (LSB = 1 • V
REF
)
4096
1.25
0
MAGNITUDE OF OFFSET CHANGE
∆OFFSET
(LSB)
0.75
0.50
0.25
0
0
1
3
4
2
REFERENCE VOLTAGE, V
REF
(V)
5
MAGNITUDE OF LINEARITY CHANGE
∆LINEARITY
(LSB)
Change in Linearity Error vs
Temperature
MAGNITUDE OF GAIN CHANGE
∆GAIN
(LSB)
0.6
0.5
0.4
0.3
0.2
0.1
0
–50 –30 –10 10 30 50 70 90 110 130
AMBIENT TEMPERATURE, T
A
(°C)
1290 • TPC07
ACLK = 4MHz
V
CC
= 5V
V
REF
= 5V
Maximum ACLK Frequency vs
Source Resistance
5
10k
V
CC
= 5V
V
REF
= 5V
T
A
= 25°C
MAXIMUM R
FILTER
** (Ω)
MAXIMUM ACLK FREQUENCY* (MHz)
4
3
2
1
0
100
1k
* MAXIMUM ACLK FREQUENCY REPRESENTS THE ACLK
FREQUENCY AT WHICH A 0.1LSB SHIFT IN THE ERROR AT
ANY CODE TRANSITION FROM ITS 4MHz VALUE IS FIRST DETECTED.
U W
Change in Gain vs Reference
Voltage
0.5
Change in Offset vs Temperature
ACLK = 4MHz
V
CC
= 5V
V
REF
= 5V
–0.1
–0.2
0.4
0.3
–0.3
0.2
–0.4
V
CC
= 5V
–0.5
1
3
2
4
REFERENCE VOLTAGE, V
REF
(V)
5
0.1
0
–50 –30 –10 10 30 50 70 90 110 130
AMBIENT TEMPERATURE, T
A
(°C)
1290 • TPC06
1290 • TPC04
1290 • TPC05
Change in Gain Error vs
Temperature
0.5
ACLK = 4MHz
V
CC
= 5V
V
REF
= 5V
0.4
0.3
0.2
0.1
0
–50 –30 –10 10 30 50 70 90 110 130
AMBIENT TEMPERATURE, T
A
(°C)
1290 • TPC08
Maximum Filter Resistor vs
Cycle Time
1k
V
IN
R
SOURCE –
+
INPUT
–
INPUT
100
R
FILTER
V
IN
C
FILTER
≥
1µF
+
–
10
10 k
R
SOURCE
(Ω)
100k
1290 • TPC09
1.0
10
100
1000
10000
1290 • TPC10
CYCLE TIME, t
CYC
(µs)
** MAXIMUM R
FILTER
REPRESENTS THE FILTER RESISTOR VALUE
AT WHICH A 0.1LSB CHANGE IN FULL-SCALE ERROR FROM
ITS VALUE AT R
FILTER
= 0 IS FIRST DETECTED.
5
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