LTC1282
3V 140ksps 12-Bit
Sampling A/D Converter
with Reference
FEATURES
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DESCRIPTIO
Single Supply 3V or
±3V
Operation
140ksps Throughput Rate
12mW (Typ) Power Dissipation
On-Chip 25ppm/°C Reference
Internal Synchronized Clock; No Clock Required
High Impedance Analog Input
69dB S/(N + D) and 77dB THD at Nyquist
±0.5LSB
INL and
±0.75LSB
DNL Max (A Grade)
2.7V Guaranteed Minimum Supply Voltage
ESD Protected On All Pins
24-Pin Narrow PDIP and SW Packages
0V to 2.5V or
±1.25V
Input Ranges
The LTC
®
1282 is a 6µs, 140ksps, sampling 12-bit A/D
converter that draws only 12mW from a single 3V or dual
±3V
supply. This easy-to-use device comes complete with
1.14µs sample-and-hold, precision reference and inter-
nally trimmed clock. Unipolar and bipolar conversion
modes provide flexibility for various applications. They are
built with LTBiCMOS
TM
switched capacitor technology.
The LTC1282 has a 25ppm/°C (max) internal reference
and converts 0V to 2.5V unipolar inputs from a single 3V
supply. With
±3V
supplies its input range is
±1.25V
with
two’s complement output format. Maximum DC specifica-
tions include
±0.5LSB
INL,
±0.75LSB
DNL and 25ppm/°C
full-scale drift over temperature. Outstanding AC perfor-
mance includes 69dB S/(N + D) and 77dB THD at the
Nyquist input frequency of 70kHz.
The internal clock is trimmed for 6µs maximum conver-
sion time. The clock automatically synchronizes to each
sample command eliminating problems with asynchro-
nous clock noise found in competitive devices. A high
speed parallel interface eases connections to FIFOs, DSPs
and microprocessors.
APPLICATI
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3V Powered Systems
High Speed Data Acquisition
Digital Signal Processing
Multiplexed Data Acquisition Systems
Audio and Telecom Processing
Spectrum Analysis
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTBiCMOS is a trademark of Linear Technology Corporation
TYPICAL APPLICATI
Single 3V Supply, 140ksps, 12-Bit Sampling A/D Converter
LTC1282
1.20V
V
REF
OUTPUT
ANALOG INPUT 1 A
V
DD
(0V TO 2.5V) 2
IN
V
REF
V
SS
3
AGND
BUSY
0.1µF
4
D11(MSB) CS
5
D10
RD
6
D9
HBEN
7
D8
NC
8
D7
NC
9
D6
D0/8
10
8- OR 12-BIT
D5
D1/9
PARALLEL BUS
11
D4
D2/10
12
DGND
D3/11
24
23
22
21
20
19
18
17
16
15
14
13
10µF
µP
CONTROL
LINES
0.1µF
3V
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
12
74
68
62
NYQUIST
FREQUENCY
56
50
ENOBs (EFFECTIVE NUMBER OF BITS)
+
11
10
9
8
7
6
5
4
3
2
1
0
1k
10k
INPUT FREQUENCY (Hz)
100k
LTC1282 • TA02
+
10µF
f
SAMPLE
= 140kHz
1282 TA01
U
S/(N + D) (dB)
UO
UO
1
LTC1282
ABSOLUTE
(Notes 1 and 2)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
A
IN
V
REF
AGND
D11(MSB)
D10
D9
D8
D7
D6
1
2
3
4
5
6
7
8
9
24 V
DD
23 V
SS
22 BUSY
21 CS
20 RD
19 HBEN
18 NC
17 NC
16 D0/8
15 D1/9
14 D2/10
13 D3/11
SW PACKAGE
24-LEAD PLASTIC SO WIDE
Supply Voltage (V
DD
) .............................................. 12V
Negative Supply Voltage (V
SS
)................... – 6V to GND
Total Supply Voltage (V
DD
to V
SS
) .......................... 12V
Analog Input Voltage
(Note 3) .............................. V
SS
– 0.3V to V
DD
+ 0.3V
Digital Input Voltage (Note 4) ........... V
SS
– 0.3V to 12V
Digital Output Voltage
(Note 3) .............................. V
SS
– 0.3V to V
DD
+ 0.3V
Power Dissipation............................................. 500mW
Specified Temperature Range (Note 14) ..... 0°C to 70°C
Operating Temperature Range
LTC1282AC, LTC1282BC ......................... 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER
PART NUMBER
LTC1282ACN
LTC1282BCN
LTC1282ACSW
LTC1282BCSW
D5 10
D4 11
DGND 12
N PACKAGE
24-LEAD PDIP
T
JMAX
= 110°C,
θ
JA
= 100°C/W (N)
T
JMAX
= 110°C,
θ
JA
= 130°C/W (SW)
Consult factory for Industrial and Military grade parts. (Note 14)
CO VERTER CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
(Note 7)
Commercial
Military
Commercial
Military
(Note 8)
q
With Internal Reference (Notes 5 and 6)
MIN
LTC1282A
TYP
MAX
±1/2
±1/2
±3/4
±3/4
±1
±3
±4
±10
±5
±0.3
±0.1
±25
±10
±0.3
±0.1
MIN
12
±1
±1
±1
±1
±1
±4
±6
±15
±45
LTC1282B
TYP
MAX
UNITS
Bits
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
ppm/°C
LSB
LSB
CONDITIONS
q
q
q
q
q
12
Differential Linearity Error
Offset Error
Gain Error
Gain Error Tempco
Power Supply Rejection
I
OUT(REF)
= 0
(Note 9) V
DD
±10%
(Note 10) V
SS
±10%
q
DY A IC ACCURACY
SYMBOL
S/(N + D)
THD
IMD
PARAMETER
(Note 5)
CONDITIONS
10kHz/70kHz Input Signal
10kHz/70kHz Input Signal, Up to 5th Harmonic
10kHz/70kHz Input Signal
f
IN1
= 19.0kHz, f
IN2
= 20.6kHz
LTC1282A/LTC1282B
MIN
TYP
MAX
71/69
– 82/– 77
– 82/– 77
– 78
4
200
UNITS
dB
dB
dB
dB
MHz
kHz
Signal-to-Noise Plus Distortion Ratio
Total Harmonic Distortion
Peak Harmonic or Spurious Noise
Intermodulation Distortion
Full Power Bandwidth
Full Linear Bandwidth (S/(N + D)
≥
68dB)
2
U
W
U
U
W W
W
W U
U
LTC1282
A ALOG I PUT
(Note 5)
SYMBOL PARAMETER
V
IN
I
IN
C
IN
t
ACQ
Analog Input Range (Note 11)
Analog Input Leakage Current
Analog Input Capacitance
Sample-and-Hold
Acquisition Time
CONDITIONS
2.7V
≤
V
DD
≤
3.6V (Unipolar Mode)
3V
≤
V
DD
≤
3.6V, – 3.3V
≤
V
SS
≤
– 2.5V (Bipolar Mode)
CS = High
Between Conversions (Sample Mode)
During Conversions (Hold Mode)
Commercial
Military
q
q
q
I TER AL REFERE CE CHARACTERISTICS
(Note 5)
PARAMETER
V
REF
Output Voltage
V
REF
Output Tempco
V
REF
Line Regulation
V
REF
Load Regulation
CONDITIONS
I
OUT
= 0
I
OUT
= 0
2.7V
≤
V
DD
≤
3.6V
– 3.6V
≤
V
SS
≤
– 2.7V
0V
≤
|
I
OUT
|
≤
1mA
q
DIGITAL I PUTS A D DIGITAL OUTPUTS
(Note 5)
SYMBOL PARAMETER
V
IH
V
IL
I
IN
C
IN
V
OH
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
V
DD
= 2.7V
I
O
= – 10µA
I
O
= – 200µA
V
DD
= 2.7V
I
O
= 160µA
I
O
= 1.6mA
V
OUT
= 0V to V
DD
, CS High
CS High (Note 12 )
V
OUT
= 0V
V
OUT
= V
DD
CONDITIONS
V
DD
= 3.6V
V
DD
= 2.7V
V
IN
= 0V to V
DD
q
q
q
V
OL
Low Level Output Voltage
I
OZ
C
OZ
I
SOURCE
I
SINK
High Z Output Leakage D11-D0/8
High Z Output Capacitance D11-D0/8
Output Source Current
Output Sink Current
POWER REQUIRE E TS
(Note 5)
SYMBOL PARAMETER
V
DD
V
SS
I
DD
I
SS
P
D
Positive Supply Voltage
Negative Supply Voltage
Positive Supply Current
Negative Supply Current
Power Dissipation
CONDITIONS
Unipolar Mode (Note 13)
Bipolar Mode (Note 13)
Bipolar Operation (Note 13)
f
SAMPLE
= 140ksps
f
SAMPLE
= 140ksps
f
SAMPLE
= 140ksps
q
q
q
U W
U
U
U
U
U
U
LTC1282A/LTC1282B
MIN
TYP
MAX
0 to 2.5
±1.25
±1
63
5
0.45
1.14
1.5
UNITS
V
V
µA
pF
pF
µs
µs
U
MIN
1.1900
LTC1282A
TYP
1.200
±5
0.55
0.02
3
MAX
1.210
±25
MIN
1.190
LTC1282B
TYP
1.200
±10
0.55
0.02
3
MAX
1.210
±45
UNITS
V
ppm/°C
LSB/V
LSB/V
LSB/mA
LTC1282A/LTC1282B
MIN
TYP
MAX
1.9
0.45
±10
5
2.6
q
UNITS
V
V
µA
pF
V
V
V
V
µA
pF
mA
mA
2.3
0.05
0.10
q
q
q
0.4
±10
15
– 4.5
4.5
LTC1282A/LTC1282B
MIN
TYP
MAX
2.7
3.0
– 3.6
4
0.03
12
3.6
3.6
– 2.5
7.8
0.15
24
UNITS
V
V
V
mA
mA
mW
3
LTC1282
TI I G CHARACTERISTICS
(Note 5)
SYMBOL
f
SAMPLE(MAX)
t
CONV
t
1
t
2
PARAMETER
Maximum Sampling Frequency
Conversion Time
CS to RD Setup Time
RD↓ to BUSY↓ Delay
C
L
= 50pF
Commercial
Military
C
L
= 20pF (Note 13)
Commercial
Military
C
L
= 100pF (Note 13)
Commercial
Military
t
4
t
5
t
6
RD Pulse Width
CS to RD Hold Time
Data Setup Time After BUSY↑
(Note 13)
(Note 13)
(Note 13)
Commercial
Military
(Note 13)
Commercial
Military
(Note 13)
(Note 13)
Commercial (Note 13)
Military (Note 13)
CONDITIONS
Commercial (Note 13)
Military (Note 13)
Commercial
Military
q
q
q
q
q
q
q
t
3
t
7
t
8
t
9
t
10
t
11
t
12
The
q
indicates 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 and
AGND wired together (unless otherwise noted).
Note 3:
When these pin voltages are taken below V
SS
or above V
DD
, they
will be clamped by internal diodes. This product can handle input currents
greater than 60mA below V
SS
or above V
DD
without latchup.
Note 4:
When these pin voltages are taken below V
SS
they will be clamped
by internal diodes. This product can handle input currents greater than
60mA below V
SS
without latchup. These pins are not clamped to V
DD
.
Note 5:
V
DD
= 3V, V
SS
= 0V for unipolar mode and V
SS
= – 3V for bipolar
mode, f
SAMPLE
= 140kHz, t
r
= t
f
= 5ns unless otherwise specified.
Note 6:
Linearity, offset and full-scale specifications apply for unipolar and
bipolar modes.
Note 7:
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.
4
UW
LTC1282A/LTC1282B
MIN
TYP
MAX
140
120
6.0
6.5
0
140
200
230
260
180
200
220
200
240
260
UNITS
kHz
kHz
µs
µs
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Data Access Time After RD↓
100
q
q
110
q
q
q
q
q
q
q
q
q
q
q
q
q
t
3
0
60
85
110
120
120
130
150
ns
ns
ns
ns
ns
ns
ns
ns
ns
Bus Relinquish Time
40
40
40
0
0
40
1140
1500
60
HBEN to RD Setup Time
HBEN to RD Hold Time
Delay Between RD Operations
Delay Between Conversions
Aperture Delay of Sample-and-Hold
450
30
ns
ns
ns
Note 8:
Bipolar offset is the different voltage measured from – 0.5LSB
when the output code flickers between 0000 0000 0000 and 1111 1111
1111.
Note 9:
Full-scale change when V
SS
= 0V (Unipolar Mode) or
– 3V (Bipolar Mode).
Note 10:
Full-scale change when V
DD
= 3V.
Note 11:
The LTC1282 can perform unipolar and bipolar conversions.
When V
SS
is grounded (i.e. – 0.1V
≤
V
SS
), the ADC will convert in unipolar
mode with input voltage of 0V to 2.5V. When V
SS
is taken negative (i.e. V
SS
≤
– 2.5V), the ADC will convert in bipolar mode with an input voltage of
±1.25V.
A
IN
must not exceed V
DD
or fall below V
SS
by more than 50mV for
specified accuracy.
Note 12:
Guaranteed by design, not subject to test.
Note 13:
Recommended operating conditions.
Note 14:
Commercial grade parts are designed to operate over the
temperature range of – 40°C to 85°C but are neither tested nor guaranteed
beyond 0°C to 70°C. Industrial grade parts specified and tested over
– 40°C to 85°C are available on special request. Consult factory.
LTC1282
TI I G CHARACTERISTICS
(Note 5)
Slow Memory Mode, Parallel Read Timing Diagram
CS
t
1
RD
t
2
BUSY
t
3
DATA
HOLD
TRACK
t
12
OLD DATA
DB11 TO DB0
t
6
t
7
NEW DATA
DB11 TO DB0
t
CONV
t
11
t
10
t
5
t
1
UW
ROM Mode, Parallel Read Timing Diagram
CS
t
1
RD
t
2
BUSY
t
3
DATA
HOLD
LTC1282 • TC01
t
4
t
5
t
11
t
CONV
t
7
t
1
t
4
t
2
t
5
t
CONV
t
7
NEW DATA
DB11 TO DB0
t
3
OLD DATA
DB11 TO DB0
t
12
t
12
TRACK
LTC1282 • TC02
Slow Memory Mode, Two Byte Read Timing Diagram
HBEN
t
8
CS
t
1
RD
t
2
BUSY
t
3
DATA
HOLD
TRACK
t
12
OLD DATA
DB7 TO DB0
t
6
t
7
NEW DATA
DB7 TO DB0
t
3
t
7
NEW DATA
DB11 TO DB8
t
12
t
10
t
CONV
t
11
t
10
t
5
t
1
t
4
t
5
t
9
t
8
t
9
LTC1282 • TC03
ROM Mode, Two Byte Read Timing Diagram
HBEN
t
8
CS
t
1
RD
t
2
BUSY
t
3
DATA
HOLD
TRACK
t
12
t
7
OLD DATA
DB7 TO DB0
t
3
t
7
NEW DATA
DB11 TO DB8
t
12
LTC1282 • TC04
t
9
t
8
t
9
t
8
t
9
t
4
t
5
t
1
t
4
t
11
t
5
t
10
t
1
t
4
t
2
t
5
t
CONV
t
3
t
7
NEW DATA
DB7 TO DB0
5
FPGA/CPLD
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