LTC1279
12-Bit, 600ksps Sampling
A/D Converter with Shutdown
FEATURES
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
s
Single Supply 5V or
±5V
Operation
Sample Rate: 600ksps
70dB S/(N + D) and 74dB THD at Nyquist
Power Dissipation: 60mW Typ
Power Shutdown with Instant Wake-Up
Internal Reference Can Be Overdriven Externally
Internal Synchronized Clock; No Clock Required
High Impedance Analog Input
Input Range: 0V to 5V or
±2.5V
New Flexible, Friendly Parallel Interface Eases
Connections to DSPs and FIFOs
24-Pin SO Wide Package
The LTC
®
1279 is a 1.4µs, 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 1.4µs 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.
APPLICATI
s
s
s
s
s
S
High Speed Data Acquisition
Digital Signal Processing
Multiplexed Data Acquisition Systems
Audio and Telecom Processing
Spectrum Analysis
TYPICAL APPLICATI
Single 5V Supply, 600kHz, 12-Bit Sampling A/D Converter
LTC1279
1
ANALOG INPUT
AV
DD
A
(0V TO 5V) 2
IN
V
REF
V
SS
3
AGND
BUSY
0.1µF
4
D11(MSB)
CS
5
D10
RD
6
D9
CONVST
7
D8
SHDN
8
D7
DV
DD
9
12-BIT
D6
D0
PARALLEL
10
D5
D1
BUS
11
D4
D2
12
DGND
D3
5V
24
23
22
21
20
19
18
17
16
15
14
13
10µF
µP
CONTROL
LINES
CONVERSION-START INPUT
POWER SHUTDOWN INPUT
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
12
11
0.1µF
EFFECTIVE NUMBER OF BITS
2.42V
REFERENCE
OUTPUT
+
+
10µF
10
9
8
7
6
5
4
3
2
1
0
10k
LTC1279 • TA01
U
74
68
NYQUIST
FREQUENCY
62
56
50
SIGNAL/(NOISE + DISTORTION) (dB)
UO
UO
f
SAMPLE
= 600kHz
100k
1M
FREQUENCY (Hz)
5M
1279 G03
1
LTC1279
ABSOLUTE
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 AV
DD
23 V
SS
22 BUSY
21 CS
20 RD
19 CONVST
18 SHDN
17 DV
DD
16 D0
15 D1
14 D2
13 D3
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*
LTC1279CSW
LTC1279ISW
D5 10
D4 11
DGND 12
SW PACKAGE
24-LEAD PLASTIC SO WIDE
T
JMAX
= 110°C,
θ
JA
= 130°C/W
*Consult factory for plastic DIP package.
Consult factory for Military grade parts.
CO VERTER CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
Differential Linearity Error
Bipolar Offset Error
Unipolar Offset Error
(Note 8)
(Note 7)
CONDITIONS
With Internal Reference (Notes 5, 6)
MIN
q
q
q
q
q
TYP
MAX
±1
±1
±4
±6
±6
±8
±15
UNITS
Bits
LSB
LSB
LSB
LSB
LSB
LSB
LSB
ppm/°C
12
Gain Error
Gain Error Tempco
I
OUT(REF)
= 0
q
±10
±45
A ALOG I PUT
SYMBOL PARAMETER
V
IN
I
IN
C
IN
(Note 5)
CONDITIONS
4.95V
≤
V
DD
≤
5.25V (Unipolar)
4.75V
≤
V
DD
≤
5.25V, – 5.25V
≤
V
SS
≤
– 2.45V (Bipolar)
CS = High
Between Conversions (Sample Mode)
During Conversions (Hold Mode)
q
q
q
MIN
TYP
0 to 5
±2.5
MAX
UNITS
V
V
Analog Input Range (Note 9)
Analog Input Leakage Current
Analog Input Capacitance
±1
25
5
2
U
µA
pF
pF
W
U
U
W W
W
U
U
U
LTC1279
DY A IC ACCURACY
SYMBOL
S/(N + D)
THD
PARAMETER
IMD
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
4.95V
≤
V
DD
≤
5.25V
– 5.25V
≤
V
SS
≤
– 4.95V
– 5mA
≤
I
OUT
≤
800µA
q
DIGITAL I PUTS A D DIGITAL OUTPUTS
(Note 5)
SYMBOL
V
IH
V
IL
I
IN
C
IN
V
OH
PARAMETER
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
V
DD
= 4.95V
I
O
= – 10µA
I
O
= – 200µA
V
DD
= 4.95V
I
O
= 160µA
I
O
= 1.6mA
V
OUT
= 0V to V
DD
, CS High
CS High (Note 9 )
V
OUT
= 0V
V
OUT
= V
DD
CONDITIONS
V
DD
= 5.25V
V
DD
= 4.95V
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 to D0
High-Z Output Capacitance D11 to D0
Output Source Current
Output Sink Current
U
U
U
W U
U
(Notes 5, 10)
CONDITIONS
100kHz Input Signal
300kHz Input Signal
100kHz Input Signal
300kHz Input Signal
100kHz Input Signal
300kHz Input Signal
f
IN1
= 94.189kHz, f
IN2
= 97.705kHz
2nd Order Terms
3rd Order Terms
f
IN1
= 299.26kHz, f
IN2
= 305.12kHz
2nd Order Terms
3rd Order Terms
q
q
q
MIN
70
TYP
72
70
– 82
– 74
– 82
– 80
– 81
– 78
– 77
– 74
5
500
MAX
UNITS
dB
dB
Signal-to-Noise Plus Distortion Ratio
Total Harmonic Distortion
First 5 Harmonics
Peak Harmonic or Spurious Noise
Intermodulation Distortion
– 78
– 78
dB
dB
dB
dB
dB
dB
dB
dB
MHz
kHz
Full Power Bandwidth
Full Linear Bandwidth (S/(N + D)
≥
68dB)
U
MIN
2.400
TYP
2.420
±10
0.01
0.01
2
MAX
2.440
±45
UNITS
V
ppm/°C
LSB/V
LSB/V
LSB/mA
MIN
2.4
TYP
MAX
0.8
±10
UNITS
V
V
µA
pF
V
V
V
V
µA
pF
mA
mA
5
4.9
q
4.0
0.05
0.10
q
q
q
0.4
±10
15
– 10
10
3
LTC1279
POWER REQUIRE E TS
SYMBOL
V
DD
V
SS
I
DD
I
SS
P
D
PARAMETER
Positive Supply Voltage (Notes 11, 12)
Negative Supply Voltage (Note 11, 12)
Positive Supply Current
Negative Supply Current
Power Dissipation
TI I G CHARACTERISTICS
SYMBOL
f
SAMPLE(MAX)
t
SAMPLE(MIN)
t
CONV
t
ACQ
t
1
t
2
t
3
t
4
t
5
PARAMETER
Maximum Sampling Frequency
Minimum Throughput Time
(Acquisition Time Plus Conversion Time)
Conversion Time
Acquisition Time
CS↓ to RD↓ Setup Time
CS↓ to CONVST↓ Setup Time
SHDN↑ to CONVST↓ Wake-Up Time
CONVST Low Time
CONVST↓ to BUSY↓ Delay
t
6
t
7
t
8
Data Ready Before BUSY↑
Wait Time RD↓ After BUSY↑
Data Access Time After RD↓
t
9
Bus Relinquish Time
t
10
t
11
t
12
RD Low Time
CONVST High Time
Aperture Delay of Sample-and-Hold
4
U W
(Note 5)
CONDITIONS
Unipolar
Bipolar
Bipolar Only
f
SAMPLE
= 600ksps
SHDN = 0V
f
SAMPLE
= 600ksps, V
SS
= – 5V
f
SAMPLE
= 600ksps
SHDN = 0V
q
q
q
q
q
MIN
4.95
4.75
– 2.45
TYP
MAX
5.25
5.25
– 5.25
UNITS
V
V
V
mA
mA
mA
mW
mW
12
1.7
0.12
60
8.5
24
3
0.30
120
15
UW
(Note 5)
CONDITIONS
q
q
q
MIN
600
TYP
MAX
1.66
UNITS
kHz
µs
µs
ns
ns
ns
1.4
160
0
20
350
40
50
1.6
(Notes 9, 11)
(Notes 9, 11)
(Note 11)
(Notes 11, 13)
C
L
= 100pF
Commercial
Industrial
C
L
= 20pF
Mode 2, (See Figure 14) (Note 9)
C
L
= 20pF (Note 9)
Commercial
Industrial
C
L
= 100pF
Commercial
Industrial
(3k and 10pF Connected as Shown in
Test Circuits)
Commercial
Industrial
(Note 9)
(Notes 9, 13)
Jitter < 50ps
q
q
ns
ns
110
130
140
ns
ns
ns
ns
ns
90
110
120
125
150
170
75
85
90
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
q
q
q
q
q
q
q
20
– 20
40
35
50
q
q
q
q
q
q
10
10
10
t
8
40
30
12
ns
LTC1279
TI I G CHARACTERISTICS
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.
TYPICAL PERFORMANCE CHARACTERISTICS
Integral Nonlinearity vs
Output Code
DIFFERENTIAL NONLINEARITY ERROR (LSB)
1.0
INTEGRAL NONLINEARITY ERROR (LSB)
f
SAMPLE
= 600kHz
0.5
EFFECTIVE NUMBER OF BITS
0
–0.5
–1.0
0
512 1024 1536 2048 2560 3072 3584 4096
OUTPUT CODE
1279 G01
U W
UW
(Note 5)
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.
Differential Nonlinearity vs
Output Code
1.0
f
SAMPLE
= 600kHz
0.5
ENOBs and S/(N + D) vs
Input Frequency
12
11
10
9
8
7
6
5
4
3
2
1
f
SAMPLE
= 600kHz
100k
1M
FREQUENCY (Hz)
5M
1279 G03
74
68
NYQUIST
FREQUENCY
62
56
50
SIGNAL/(NOISE + DISTORTION) (dB)
0
–0.5
–1.0
0
512 1024 1536 2048 2560 3072 3584 4096
OUTPUT CODE
1279 G02
0
10k
5
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
