1
LTC1279
12-Bit, 600ksps Sampling
A/D Converter with Shutdown
S
FEATURE
D
U
ESCRIPTIO
s
Single Supply 5V or
5V Operation
s
Sample Rate: 600ksps
s
70dB S/(N + D) and 74dB THD at Nyquist
s
Power Dissipation: 60mW Typ
s
Power Shutdown with Instant Wake-Up
s
Internal Reference Can Be Overdriven Externally
s
Internal Synchronized Clock; No Clock Required
s
High Impedance Analog Input
s
Input Range: 0V to 5V or
2.5V
s
New Flexible, Friendly Parallel Interface Eases
Connections to DSPs and FIFOs
s
24-Pin SO Wide Package
U
A
O
PPLICATI
TYPICAL
The LTC
1279 is a 1.4
s, 600ksps, sampling 12-bit A/D
converter which draws only 60mW from a single 5V or
5V supplies. This easy-to-use device comes complete
with a 160ns sample-and-hold, a precision reference and
an internally trimmed clock. Unipolar and bipolar conver-
sion modes add to the flexibility of the ADC. The low
power dissipation is reduced even more, drawing only
8.5mW in power shutdown mode. Instant wake-up from
power shutdown allows the converter to be powered
down even during brief inactive periods.
The LTC1279 converts 0V to 5V unipolar inputs from a
single 5V supply and
2.5V bipolar inputs from
5V
supplies. Maximum DC specs include
1LSB INL and
1LSB DNL. Outstanding guaranteed AC performance
includes 70dB S/(N + D) and 78dB THD at the input
frequency of 100kHz over temperature.
The internal clock is trimmed for 1.4
s conversion time.
The clock automatically synchronizes to each sample
command, eliminating problems with asynchronous clock
noise found in competitive devices. A separate conversion
start input and a data-ready signal (BUSY) ease connec-
tions to FIFOs, DSPs and microprocessors.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Single 5V Supply, 600kHz, 12-Bit Sampling A/D Converter
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
A
IN
V
REF
AGND
D11(MSB)
D10
D9
D8
D7
D6
D5
D4
DGND
AV
DD
V
SS
BUSY
CS
RD
CONVST
SHDN
DV
DD
D0
D1
D2
D3
LTC1279
+
0.1
F
10
F
2.42V
REFERENCE
OUTPUT
ANALOG INPUT
(0V TO 5V)
10
F
0.1
F
5V
12-BIT
PARALLEL
BUS
P CONTROL
LINES
LTC1279 TA01
+
CONVERSION-START INPUT
POWER SHUTDOWN INPUT
U
S
A
O
PPLICATI
s
High Speed Data Acquisition
s
Digital Signal Processing
s
Multiplexed Data Acquisition Systems
s
Audio and Telecom Processing
s
Spectrum Analysis
FREQUENCY (Hz)
10k
EFFECTIVE NUMBER OF BITS
SIGNAL/(NOISE + DISTORTION) (dB)
100k
1M
5M
1279 G03
12
11
10
9
8
7
6
5
4
3
2
1
0
74
68
62
56
50
f
SAMPLE
= 600kHz
NYQUIST
FREQUENCY
2
LTC1279
AV
DD
= DV
DD
= V
DD
(Notes 1, 2)
Supply Voltage (V
DD
) ................................................ 7V
Negative Supply Voltage (V
SS
)
Bipolar Operation Only ......................... 6V to GND
Total Supply Voltage (V
DD
to V
SS
)
Bipolar Operation Only ....................................... 12V
Analog Input Voltage (Note 3)
Unipolar Operation ................... 0.3V to V
DD
+ 0.3V
Bipolar Operation............... V
SS
0.3V to V
DD
+ 0.3V
Digital Input Voltage (Note 4)
Unipolar Operation ............................... 0.3V to 12V
Bipolar Operation.......................... V
SS
0.3V to 12V
Digital Output Voltage
Unipolar Operation ................... 0.3V to V
DD
+ 0.3V
Bipolar Operation..................... 0.3V to V
DD
+ 0.3V
Power Dissipation ............................................. 500mW
Operating Temperature Range
LTC1279C ............................................... 0
C to 70
C
LTC1279I ........................................... 40
C to 85
C
Storage Temperature Range ................ 65
C to 150
C
Lead Temperature (Soldering, 10 sec) ................. 300
C
ORDER
PART NUMBER*
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
W
U
U
PACKAGE/ORDER I FOR ATIO
PUT
U
I
A
A
U
LOG
C
C
HARA TERISTICS
CO
U
VERTER
With Internal Reference (Notes 5, 6)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Analog Input Range (Note 9)
4.95V
V
DD
5.25V (Unipolar)
q
0 to 5
V
4.75V
V
DD
5.25V, 5.25V
V
SS
2.45V (Bipolar)
q
2.5
V
I
IN
Analog Input Leakage Current
CS = High
q
1
A
C
IN
Analog Input Capacitance
Between Conversions (Sample Mode)
25
pF
During Conversions (Hold Mode)
5
pF
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
q
12
Bits
Integral Linearity Error
(Note 7)
q
1
LSB
Differential Linearity Error
q
1
LSB
Bipolar Offset Error
(Note 8)
4
LSB
q
6
LSB
Unipolar Offset Error
6
LSB
q
8
LSB
Gain Error
15
LSB
Gain Error Tempco
I
OUT(REF)
= 0
q
10
45
ppm/
C
(Note 5)
*Consult factory for plastic DIP package.
Consult factory for Military grade parts.
LTC1279CSW
LTC1279ISW
T
JMAX
= 110
C,
JA
= 130
C/W
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
SW PACKAGE
24-LEAD PLASTIC SO WIDE
24
23
22
21
20
19
18
17
16
15
14
13
A
IN
V
REF
AGND
D11 (MSB)
D10
D9
D8
D7
D6
D5
D4
DGND
AV
DD
V
SS
BUSY
CS
RD
CONVST
SHDN
DV
DD
D0
D1
D2
D3
3
LTC1279
ACCURACY
IC
DY
U
W
A
I TER AL REFERE CE CHARACTERISTICS
U
U
U
DIGITAL I PUTS A D DIGITAL OUTPUTS
U
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
V
DD
= 5.25V
q
2.4
V
V
IL
Low Level Input Voltage
V
DD
= 4.95V
q
0.8
V
I
IN
Digital Input Current
V
IN
= 0V to V
DD
q
10
A
C
IN
Digital Input Capacitance
5
pF
V
OH
High Level Output Voltage
V
DD
= 4.95V
I
O
= 10
A
4.9
V
I
O
= 200
A
q
4.0
V
V
OL
Low Level Output Voltage
V
DD
= 4.95V
I
O
= 160
A
0.05
V
I
O
= 1.6mA
q
0.10
0.4
V
I
OZ
High-Z Output Leakage D11 to D0
V
OUT
= 0V to V
DD
, CS High
q
10
A
C
OZ
High-Z Output Capacitance D11 to D0
CS High (Note 9 )
q
15
pF
I
SOURCE
Output Source Current
V
OUT
= 0V
10
mA
I
SINK
Output Sink Current
V
OUT
= V
DD
10
mA
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
S/(N + D)
Signal-to-Noise Plus Distortion Ratio
100kHz Input Signal
q
70
72
dB
300kHz Input Signal
70
dB
THD
Total Harmonic Distortion
100kHz Input Signal
q
82
78
dB
First 5 Harmonics
300kHz Input Signal
74
dB
Peak Harmonic or Spurious Noise
100kHz Input Signal
q
82
78
dB
300kHz Input Signal
80
dB
IMD
Intermodulation Distortion
f
IN1
= 94.189kHz, f
IN2
= 97.705kHz
2nd Order Terms
81
dB
3rd Order Terms
78
dB
f
IN1
= 299.26kHz, f
IN2
= 305.12kHz
2nd Order Terms
77
dB
3rd Order Terms
74
dB
Full Power Bandwidth
5
MHz
Full Linear Bandwidth (S/(N + D)
68dB)
500
kHz
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
REF
Output Voltage
I
OUT
= 0
2.400
2.420
2.440
V
V
REF
Output Tempco
I
OUT
= 0
q
10
45
ppm/
C
V
REF
Line Regulation
4.95V
V
DD
5.25V
0.01
LSB/V
5.25V
V
SS
4.95V
0.01
LSB/V
V
REF
Load Regulation
5mA
I
OUT
800
A
2
LSB/mA
(Notes 5, 10)
(Note 5)
(Note 5)
4
LTC1279
POWER REQUIRE E TS
W U
(Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
DD
Positive Supply Voltage (Notes 11, 12)
Unipolar
4.95
5.25
V
Bipolar
4.75
5.25
V
V
SS
Negative Supply Voltage (Note 11, 12)
Bipolar Only
2.45
5.25
V
I
DD
Positive Supply Current
f
SAMPLE
= 600ksps
q
12
24
mA
SHDN = 0V
q
1.7
3
mA
I
SS
Negative Supply Current
f
SAMPLE
= 600ksps, V
SS
= 5V
q
0.12
0.30
mA
P
D
Power Dissipation
f
SAMPLE
= 600ksps
q
60
120
mW
SHDN = 0V
q
8.5
15
mW
TI I G CHARACTERISTICS
W U
(Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
SAMPLE(MAX)
Maximum Sampling Frequency
q
600
kHz
t
SAMPLE(MIN)
Minimum Throughput Time
q
1.66
s
(Acquisition Time Plus Conversion Time)
t
CONV
Conversion Time
q
1.4
1.6
s
t
ACQ
Acquisition Time
160
ns
t
1
CS
to RD
Setup Time
(Notes 9, 11)
q
0
ns
t
2
CS
to CONVST
Setup Time
(Notes 9, 11)
q
20
ns
t
3
SHDN
to CONVST
Wake-Up Time
(Note 11)
350
ns
t
4
CONVST Low Time
(Notes 11, 13)
q
40
ns
t
5
CONVST
to BUSY
Delay
C
L
= 100pF
50
110
ns
Commercial
q
130
ns
Industrial
q
140
ns
t
6
Data Ready Before BUSY
C
L
= 20pF
q
20
40
ns
t
7
Wait Time RD
After BUSY
Mode 2, (See Figure 14) (Note 9)
q
20
ns
t
8
Data Access Time After RD
C
L
= 20pF (Note 9)
35
90
ns
Commercial
q
110
ns
Industrial
q
120
ns
C
L
= 100pF
50
125
ns
Commercial
q
150
ns
Industrial
q
170
ns
t
9
Bus Relinquish Time
(3k and 10pF Connected as Shown in
Test Circuits)
10
30
75
ns
Commercial
q
10
85
ns
Industrial
q
10
90
ns
t
10
RD Low Time
(Note 9)
q
t
8
ns
t
11
CONVST High Time
(Notes 9, 13)
q
40
ns
t
12
Aperture Delay of Sample-and-Hold
Jitter < 50ps
12
ns
5
LTC1279
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.
Note 8: Bipolar offset is the offset voltage measured from 1/2LSB when
the output code flickers between 0000 0000 0000 and 1111 1111 1111.
Note 9: Guaranteed by design, not subject to test.
Note 10: The AC test is for bipolar mode. The signal-to-noise plus
distortion ratio is about 1dB lower for unipolar mode, so the typical
S/(N + D) at 100kHz in unipolar mode is 71dB.
Note 11: Recommended operating conditions.
Note 12: A
IN
must not exceed V
DD
or fall below V
SS
by more than 50mV for
specified accuracy. Therefore the minimum supply voltage for the unipolar
mode is 4.95V. The minimum for the bipolar mode is 4.75V, 2.45V.
Note 13: The falling CONVST edge starts a conversion. If CONVST returns
high at a bit decision point during the conversion it can create small errors.
For best performance ensure that CONVST returns high either within 120ns
after conversion start (i.e., before the first bit decision) or after BUSY rises
(i.e., after the last bit test). See mode 1a and 1b (Figures 12 and 13) timing
diagrams.
TI I G CHARACTERISTICS
W U
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 the analog input voltage is taken below V
SS
(ground for
unipolar mode) or above V
DD
, it will be clamped by internal diodes. This
product can handle input currents greater than 80mA below V
SS
(ground
for unipolar mode) or above V
DD
without latch-up.
Note 4: When these pin voltages are taken below V
SS
(ground for unipolar
mode), they will be clamped by internal diodes. This product can handle
input currents greater than 60mA below V
SS
(ground for unipolar mode)
without latch-up. These pins are not clamped to V
DD
.
Note 5: AV
DD
= DV
DD
= V
DD
= 5V, (V
SS
= 5V for bipolar mode), f
SAMPLE
=
600kHz, t
r
= t
f
= 5ns unless otherwise specified.
Note 6: Linearity, offset and full scale specifications apply for unipolar and
bipolar modes.
(Note 5)
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
OUTPUT CODE
0
DIFFERENTIAL NONLINEARITY ERROR (LSB)
4096
1279 G02
1024
2048
3072
1.0
0.5
0
0.5
1.0
512
1536
2560
3584
f
SAMPLE
= 600kHz
OUTPUT CODE
0
INTEGRAL NONLINEARITY ERROR (LSB)
4096
1279 G01
1024
2048
3072
1.0
0.5
0
0.5
1.0
512
1536
2560
3584
f
SAMPLE
= 600kHz
Integral Nonlinearity vs
Output Code
FREQUENCY (Hz)
10k
EFFECTIVE NUMBER OF BITS
SIGNAL/(NOISE + DISTORTION) (dB)
100k
1M
5M
1279 G03
12
11
10
9
8
7
6
5
4
3
2
1
0
74
68
62
56
50
f
SAMPLE
= 600kHz
NYQUIST
FREQUENCY
ENOBs and S/(N + D) vs
Input Frequency
Differential Nonlinearity vs
Output Code
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