LTC1283
3V Single Chip 10-Bit Data
Acquisition System
FEATURES
s
s
DESCRIPTIO
s
s
s
Single Supply 3.3V or
±3.3V
Operation
Software Programmable Features:
Unipolar/Bipolar Conversions
4 Differential/8 Single-Ended Inputs
MSB- or LSB-First Data Sequence
Variable Data Word Length
Built-In Sample-and-Hold
Direct 4-Wire Interface to Most MPU Serial Ports
and all MPU Parallel Ports
15kHz Maximum Throughput Rate
The LTC1283 is a 3V 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 10-bit unipolar, or 9-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.
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-, 10-, 12-, or
16-bit. This allows easy interface to shift registers and a
variety of processors.
Both the LTC1283A and LTC1283 are specified with offset
and linearity errors less than
±0.5LSB.
The LTC1283A has
a gain error limit of
±1LSB.
The 1283 is specified with a
gain error limit of
±2LSB
for applications where gain is
adjustable or less critcial.
LTCMOS is a trademark of Linear Technology Corp.
KEY SPECIFICATIO S
s
s
s
s
s
s
s
Minimum Guaranteed Supply Voltage: 3V
Resolution: 10 Bits
Offset Error:
±0.5LSB
Max
Linearity Error:
±0.5LSB
Max
Gain Error (LTC1283A):
±1LSB
Max
Conversion Time: 44µs
Supply Current: 350µA Max, 150µA Typ
TYPICAL APPLICATI
4.7µF
3V
LTC1283
DIFFERENTIAL
INPUT
3V
BIPOLAR
INPUT
–3V
3V
D
OUT
D
IN
SCLK
T
UNIPOLAR
INPUTS
CS
FOR 83CL410 CODE SEE
APPLICATIONS INFORMATION SECTION
MPU
(e.g., 83CL410)
1.0
0.5
ERROR (LSBs)
0
P1.1
P1.2
P1.3
P1.4
SERIAL DATA LINK
–0.5
– 1.0
0
(+)
(–)
–UNIPOLAR
INPUT
LTC1283 • TA01
–3V
U
Linearity Plot
512
OUTPUT CODE
LTC1283 • TA02
UO
U
1024
1
LTC1283
ABSOLUTE
AXI U
RATI GS
(Notes 1 and 2)
Negative Supply Voltage (V–) ..................... –6V to GND
Power Dissipation.............................................. 500mW
Operating Temperature
LTC1283AC, LTC1283C ......................... 0°C to 70°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
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
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
–
11 AGND
ORDER PART
NUMBER
LTC1283ACN
LTC1283CN
DGND 10
N PACKAGE
20-LEAD PLASTIC DIP
T
J MAX
= 150°C,
θ
JA
= 100°C/W
Consult factory for Industrial and Military grade parts
RECO
SYMBOL
V
CC
V
–
f
SCLK
f
ACLK
E DED OPERATI G CO DITIO S
CONDITIONS
V
–
= 0V
V
CC
= 3.3V
V
CC
= 3V
V
CC
= 3V
T
A
≤
25°C
T
A
≤
70°C
See Operating Sequence
V
CC
= 3V
V
CC
= 3V
V
CC
= 3V
V
CC
= 3V
V
CC
= 3V
V
CC
= 3V
V
CC
= 3V
LTC1283/LTC1283A
MIN
TYP
MAX
3.0
– 3.6
0
0.01
0.05
10 SCLK +
48 ACLK
0
200
2 ACLK Cycles
+ 1µs
400
250
400
44
ns
ns
ns
ACLK
Cycles
3.6
0
500
1.00
1.00
UNITS
V
V
kHz
MHz
MHz
Cycles
ns
ns
PARAMETER
Positive Supply Voltage
Negative Supply Voltage
Shift Clock Frequency
A/D Clock Frequency
t
CYC
t
hCS
t
hDI
t
suCS
t
suDI
t
WHACLK
t
WLACLK
t
WHCS
Total Cycle Time
Hold Time, CS Low After Last SCLK↓
Hold Time, D
IN
After SCLK↑
Setup Time CS↓ Before Clocking in First Address Bit (Note 8)
Setup Time, D
IN
Stable Before SCLK↑
ACLK High Time
ACLK Low Time
CS High Time During Conversion
2
U
U
U
U
U
W
W W
U
W
TOP VIEW
CH0 1
CH1 2
CH2 3
CH3 4
CH4 5
CH5 6
CH6 7
CH7 8
COM 9
DGND 10
20 V
CC
19 ACLK
18 SCLK
17 D
IN
16 D
OUT
15 CS
14 REF
+
13 REF
–
12 V
–
11 AGND
S PACKAGE
20-LEAD PLASTIC SOL
T
J MAX
= 150°C,
θ
JA
= 130°C/W
ORDER PART
NUMBER
LTC1283ACS
LTC1283CS
U WW
LTC1283
CO VERTER A D
PARAMETER
Offset Error
Linearity Error
Gain Error
Minimum Resolution for Which No
Missing Codes are Guaranteed
Reference Input Resistance
Analog and REF Input Range
On Channel Leakage Current
(Note 7)
(Note 6)
On Channel = 3V
Off Channel = 0V
On Channel = 0V
Off Channel = 3V
Off Channel Leakage Current
(Note 7)
On Channel = 3V
Off Channel = 0V
On Channel = 0V
Off Channel = 3V
q
q
q
q
AC CHARACTERISTICS
(Note 3)
SYMBOL
t
ACC
t
SMPL
t
CONV
t
dDO
t
dis
t
en
t
hDO
t
f
t
r
C
IN
PARAMETER
Delay Time From CS↓ to D
OUT
Data Valid
Analog Input Sample Time
Conversion Time
Delay Time, SCLK↓ to D
OUT
Data Valid
Delay Time, CS↑ to D
OUT
Hi-Z
Delay Time, 2nd CLK↓ to D
OUT
Enabled
Time Output Data Remains Valid After SCLK↓
D
OUT
Fall Time
D
OUT
Rise Time
Input Capacitance
See Test Circuits
See Test Circuits
Analog Inputs On Channel
Off Channel
Digital Inputs
q
q
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
(Note 3)
SYMBOL
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
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
CONDITIONS
V
CC
= 3.6V
V
CC
= 3V
V
IN
= V
CC
V
IN
= 0V
V
CC
= 3V, I
O
= – 20µA
I
O
= – 200µA
V
CC
= 3V, I
O
= 20µA
I
O
= 400µA
q
q
q
q
q
q
W U
U
U
ULTIPLEXER CHARACTERISTICS
(Note 3)
CONDITIONS
(Note 4)
(Notes 4 and 5)
(Note 4)
q
q
q
q
LTC1283A
MIN
TYP
MAX
±0.5
±0.5
±1.0
10
10
LTC1283
MIN
TYP
MAX
±0.5
±0.5
±2.0
10
10
UNITS
LSB
LSB
LSB
Bits
kΩ
V
(V
–
) – 0.05V to V
CC
+ 0.05V
1
–1
–1
1
1
–1
–1
1
µA
µA
µA
µA
CONDITIONS
(Note 8)
See Operating Sequence
See Operating Sequence
See Test Circuts
See Test Circuits
See Test Circuits
q
q
q
LTC1283/LTC1283A
MIN
TYP
MAX
2
5
44
400
240
300
75
90
80
65
5
5
300
300
900
500
800
UNITS
ACLK Cycles
SCLK Cycles
ACLK Cycles
ns
ns
ns
ns
ns
ns
pF
pF
pF
LTC1283/LTC1283A
MIN
TYP
MAX
1.7
0.45
2.5
– 2.5
2.6
2.0
2.8
0.05
0.10
UNITS
V
V
µA
µA
V
V
0.30
V
V
3
LTC1283
DIGITAL A D DC ELECTRICAL CHARACTERISTICS
(Note 3)
SYMBOL
I
OZ
I
SOURCE
I
SINK
I
CC
I
REF
I
–
PARAMETER
Hi-Z Output Leakage
Output Source Current
Output Sink Current
Positive Supply Current
Reference Current
Negative Supply Current
CONDITIONS
V
OUT
= V
CC
, CS High
V
OUT
= 0V, CS High
V
OUT
= 0V
V
OUT
= V
CC
CS High, REF
+
Open
V
REF
= 2.5V
CS High, V
–
= – 3V
q
q
q
q
q
The
q
denotes specifications which apply over the 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
= 3V, V
REF+
= 2.5V, V
REF–
= 0V, V
–
= 0V for unipolar mode
and – 3V for bipolar mode, ACLK = 1MHz, SCLK = 0.25MHz unless
otherwise specified.
Note 4:
These specifications apply for both unipolar and bipolar modes. In
bipolar mode, one LSB is equal to the bipolar input span (2V
REF
) divided
by 1024. For example, when V
REF
= 2.5V, 1LSB (bipolar) = 2(2.5V)/1024 =
4.88mV.
Note 5:
Linearity error is the deviation from ideal of the slope between the
two end points of the transfer curve.
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Temperature
250
REF
+
OPEN
ACLK = 500kHz
V
CC
= CS = 3V
SUPPLY CURRENT, I
CC
(µA)
200
400
1
×
V
REF
)
1024
OFFSET ERROR (LSBs =
I
REF
(µA)
150
100
50
0
50
25
0
75 100
–50 –25
AMBIENT TEMPERATURE (°C)
4
U W
U
LTC1283/LTC1283A
MIN
TYP
MAX
3
–3
– 4.5
4.5
150
250
–1
350
500
– 50
UNITS
µA
µA
mA
mA
µA
µA
µA
Note 6:
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, as high level reference or analog inputs 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.
Note 7:
Channel leakage current is measured after the channel selection.
Note 8:
To minimize errors caused by noise at the chip select input, the
internal circuitry waits for two ACLK falling edges 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.
Reference Current vs Temperature
500
V
CC
= 3V
V
REF
= 2.5V
10
9
8
7
6
5
4
3
2
1
0
Unadjusted Offset Error
vs Reference Voltage
V
CC
= 3V
ACLK = 500kHz
300
200
100
125
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
0
0.5
1.5
2.0
1.0
REFERENCE VOLTAGE (V)
2.5
LTC1283 • G01
LTC1283 • G02
LTC1283 • G03
LTC1283
TYPICAL PERFOR A CE CHARACTERISTICS
MAGNITUDE OF OFFSET CHANGE,
∆
OFFSET (LSB)
Change in Full-Scale Error
vs Reference Voltage
1.0
0.9
1
×
V
REF
)
1024
V
CC
= 3V
ACLK = 500kHz
CHANGE IN GAIN ERROR (LSB)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.5
1.5
2.0
1.0
REFERENCE VOLTAGE (V)
2.5
LINEARITY ERROR (LSBs =
MAGNITUDE OF LINEARITY CHANGE,
∆
LINEARITY (LSB)
Change in Linearity Error
vs Temperature
MAGNITUDE OF GAIN CHANGE,
∆
GAIN (LSB)
0.5
V
CC
= 3V
V
REF
= 2.5V
ACLK = 500kHz
0.5
MAXIMUM ACLK FREQUENCY* (MHz)
0.4
0.3
0.2
0.1
0
50
25
0
75 100
–50 –25
AMBIENT TEMPERATURE (°C)
Maximum Conversion Clock Rate
vs Reference Voltage
1500
V
CC
= 3V
MAXIMUM ACLK FREQUENCY* (kHz)
MAXIMUM ACLK FREQUENCY* (kHz)
1250
1000
750
500
250
0
0
0.5
1.0
1.5
2.0
REFERENCE VOLTAGE (V)
2.5
MAXIMUM R
FILTER
** (Ω)
*Maximum ACLK frequency represents the ACLK frequency at which a 0.1LSB shift in the error at
any code transition from its 100kHz value is first detected.
U W
LTC1283 • G04
Linearity Error
vs Reference Voltage
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.5
1.5
2.0
1.0
REFERENCE VOLTAGE (V)
2.5
V
CC
= 3V
ACLK = 500kHz
Change in Offset Error
vs Temperature
0.5
V
CC
= 3V
V
REF
= 2.5V
ACLK = 500kHz
0.4
0.3
0.2
0.1
0
50
25
75 100
0
–50 –25
AMBIENT TEMPERATURE (°C)
125
LTC1283 • G05
LTC1283 • G06
Change in Gain Error
vs Temperature
2.0
V
CC
= 3V
V
REF
= 2.5V
ACLK = 500kHz
Maximum Conversion Clock Rate
vs Temperature
1.75
1.5
1.25
1.0
0.75
0.5
0.25
0
–50
–25
75 100
0
50
25
AMBIENT TEMPERATURE (˚C)
125
V
CC
= 3V
V
REF
= 2.5V
0.4
0.3
0.2
0.1
125
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
LTC1283 • G07
LTC1283 • G08
LTC1283 • G09
Maximum Conversion Clock Rate
vs Source Resistance
1500
1250
10k
Maximum Filter Resistor
vs Cycle Time
100k
R
FILTER
C
FILTER
≥
1µF
–
V
IN
+
V
CC
= 3V
V
CC
= 3V
1000
750
V
IN
+ INPUT
1k
500
– INPUT
100
250
0
1
R
SOURCE–
10
R
SOURCE
(kΩ)
100
LTC1283 • G11
10
10
100
1000
10000
LTC1283 • G12
CYCLE TIME (µs)
LTC1283 • G10
**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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