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1
LTC1409
12-Bit, 800ksps Sampling
A/D Converter with Shutdown
S
FEATURE
D
U
ESCRIPTIO
The LTC
1409 is a 1
s, 800ksps, sampling 12-bit A/D
converter that draws only 80mW from
5V supplies. This
easy-to-use device includes a high dynamic range sample-
and-hold and a precision reference. Two digitally selectable
power Shutdown modes provide flexibility for low power
systems.
The LTC1409 full-scale input range is
2.5V. Maximum
DC specs include
1LSB INL and
1LSB DNL over tem-
perature. Outstanding AC performance includes 72.5dB
S/(N + D) at the Nyquist input frequency of 400kHz.
The unique differential input sample-and-hold can acquire
single-ended or differential input signals up to its 20MHz
bandwidth. The 60dB common mode rejection allows
users to eliminate ground loops and common mode noise
by measuring signals differentially from the source.
The ADC has a
P compatible, 12-bit parallel output port.
There is no pipeline delay in the conversion results.
A separate convert start input and a data ready signal
(BUSY) ease connections to FIFOs, DSPs and micropro-
cessors. A digital output driver power supply pin allows
direct connection to 3V logic.
s
Sample Rate: 800ksps
s
Power Dissipation: 80mW
s
72.5dB S/(N + D) and 86dB THD at Nyquist
s
No Pipeline Delay
s
Nap (4mW) and Sleep (10
W) Shutdown Modes
s
Operates with Internal 15ppm/
C Reference
or External Reference
s
True Differential Inputs Reject Common Mode Noise
s
20MHz Full Power Bandwidth Sampling
s
2.5V Bipolar Input Range
s
28-Pin SO Wide and SSOP Package
U
S
A
O
PPLICATI
s
Telecommunications
s
Digital Signal Processing
s
Multiplexed Data Acquisition Systems
s
High Speed Data Acquisition
s
Spectrum Analysis
s
Imaging Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
U
A
O
PPLICATI
TYPICAL
800kHz, 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
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
+A
IN
A
IN
V
REF
REFCOMP
AGND
D11(MSB)
D10
D9
D8
D7
D6
D5
D4
DGND
AV
DD
OV
DD
V
SS
BUSY
CS
CONVST
RD
SHDN
NAP/SLP
OGND
D0
D1
D2
D3
LTC1409
10
F
DIFFERENTIAL
ANALOG INPUT
(2.5V TO 2.5V)
2.50V
V
REF
OUTPUT
10
F
10
F
5V
5V
12-BIT
PARALLEL
BUS
P CONTROL
LINES
LTC1409 TA01
INPUT FREQUENCY (Hz)
2
EFFECTIVE BITS
S/(N + D) (dB)
4
6
8
10
10k
100k
1M
10M
LTC1409 TA02
0
1k
12
74
68
62
56
50
NYQUIST
FREQUENCY
f
SAMPLE
= 800ksps
2
LTC1409
AV
DD
= OV
DD
= V
DD
(Notes 1, 2)
Supply Voltage (V
DD
) ................................................ 6V
Negative Supply Voltage (V
SS
)................................ 6V
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 10V
Digital Output Voltage ............. V
SS
0.3V to V
DD
+ 0.3V
Power Dissipation ............................................. 500mW
Operating Temperature Range
LTC1409C............................................... 0
C to 70
C
LTC1409I ........................................... 40
C to 85
C
Storage Temperature Range ................ 65
C to 150
C
Lead Temperature (Soldering, 10 sec)................. 300
C
A
U
G
W
A
W
U
W
A
R
BSOLUTE
XI
TI
S
W
U
U
PACKAGE/ORDER I FOR ATIO
Consult factory for Military grade parts.
ORDER
PART NUMBER
LTC1409CG
LTC1409CSW
LTC1409IG
LTC1409ISW
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
q
12
Bits
Integral Linearity Error
(Note 7)
q
0.3
1
LSB
Differential Linearity Error
q
0.3
1
LSB
Offset Error
(Note 8)
2
6
LSB
q
8
LSB
Full-Scale Error
15
LSB
Full-Scale Tempco
I
OUT(REF)
= 0
q
15
ppm/
C
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)
4.75V
V
DD
5.25V, 5.25V
V
SS
4.75V
q
2.5
V
I
IN
Analog Input Leakage Current
CS = High
q
1
A
C
IN
Analog Input Capacitance
Between Conversions
17
pF
During Conversions
5
pF
t
ACQ
Sample-and-Hold Acquisition Time
q
50
150
ns
t
AP
Sample-and-Hold Aperture Delay Time
1.5
ns
t
jitter
Sample-and-Hold Aperture Delay Time Jitter
5
ps
RMS
CMRR
Analog Input Common Mode Rejection Ratio
2.5V < (A
IN
= +A
IN
) < 2.5V
60
dB
(Note 5)
PUT
U
I
A
A
U
LOG
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
+A
IN
A
IN
V
REF
REFCOMP
AGND
D11(MSB)
D10
D9
D8
D7
D6
D5
D4
DGND
AV
DD
OV
DD
V
SS
BUSY
CS
CONVST
RD
SHDN
NAP/SLP
OGND
D0
D1
D2
D3
SW PACKAGE
28-LEAD PLASTIC SO WIDE
G PACKAGE
28-LEAD PLASTIC SO
TOP VIEW
T
JMAX
= 110
C,
JA
= 95
C/W (G)
T
JMAX
= 110
C,
JA
= 130
C/W (SW)
3
LTC1409
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
S/(N + D)
Signal-to-Noise Plus Distortion Ratio 100kHz Input Signal (Note 12)
q
70
73.0
dB
400kHz Input Signal (Note 12)
q
68
72.5
dB
THD
Total Harmonic Distortion
100kHz Input Signal, First Five Harmonics
90
dB
400kHz Input Signal, First Five Harmonics
q
86
74
dB
Peak Harmonic or Spurious Noise
400kHz Input Signal
q
90
74
dB
IMD
Intermodulation Distortion
f
IN1
= 29.37kHz, f
IN2
= 32.446kHz
84
dB
Full Power Bandwidth
15
MHz
Full Linear Bandwidth
S/(N + D)
68dB
1.6
MHz
(Note 5)
ACCURACY
IC
DY
U
W
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
REF
Output Voltage
I
OUT
= 0
2.480
2.500
2.520
V
V
REF
Output Tempco
I
OUT
= 0
15
ppm/
C
V
REF
Line Regulation
4.75V
V
DD
5.25V
0.01
LSB/V
5.25V
V
SS
4.75V
0.01
LSB/V
V
REF
Output Resistance
0.1mA
|
I
OUT
|
0.1mA
4
k
REFCOMP Output Voltage
I
OUT
= 0
4.06
V
(Note 5)
I TER AL REFERE CE CHARACTERISTICS
U
U
U
(Note 5)
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
= 4.75V
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
= 4.75V
I
O
= 10
A
4.5
V
I
O
= 200
A
q
4.0
V
V
OL
Low Level Output Voltage
V
DD
= 4.75V
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
(Note 5)
DIGITAL I PUTS A D DIGITAL OUTPUTS
U
U
POWER REQUIRE E TS
W U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
DD
Positive Supply Voltage
(Notes 10, 11)
4.75
5.25
V
V
SS
Negative Supply Voltage
(Note 10)
4.75
5.25
V
I
DD
Positive Supply Current
CS High
q
6.0
9.0
mA
Nap Mode
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 5V
0.8
1.2
mA
Sleep Mode
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 0V
1.0
A
4
LTC1409
POWER REQUIRE E TS
W U
(Note 5)
TI I G CHARACTERISTICS
W U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
SAMPLE(MAX)
Maximum Sampling Frequency
q
800
kHz
t
CONV
Conversion Time
q
900
1250
ns
t
ACQ
Acquisition Time
q
150
ns
t
1
CS to RD Setup Time
(Notes 9, 10)
q
0
ns
t
2
CS
to CONVST
Setup Time
(Notes 9, 10)
q
10
ns
t
3
NAP/SLP
to SHDN
Setup Time
(Notes 9, 10)
q
10
ns
t
4
SHDN
to CONVST
Wake-Up Time
(Note 10)
200
ns
t
5
CONVST
Low Time
(Notes 10, 11)
q
50
ns
t
6
CONVST to BUSY Delay
C
L
= 25pF
10
ns
q
60
ns
t
7
Data Ready Before BUSY
20
35
ns
q
15
ns
t
8
Delay Between Conversions
(Note 10)
q
40
ns
t
9
Wait Time RD
After BUSY
q
5
ns
t
10
Data Access Time After RD
C
L
= 25pF
15
35
ns
q
45
ns
C
L
= 100pF
20
45
ns
q
60
ns
t
11
Bus Relinquish Time
8
30
ns
0
C
T
A
70
C
q
35
ns
40
C
T
A
85
C
q
40
ns
t
12
RD Low Time
q
t
10
ns
t
13
CONVST High Time
q
50
ns
t
14
Aperture Delay of Sample-and-Hold
1.5
ns
Note 5: V
DD
= 5V, f
SAMPLE
= 800kHz, t
r
= t
f
= 5ns unless otherwise
specified.
Note 6: Linearity, offset and full-scale specifications apply for a single-
ended +A
IN
input with A
IN
grounded.
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 0.5LSB when
the output code flickers between 0000 0000 0000 and 1111 1111 1111.
Note 9: Guaranteed by design, not subject to test.
Note 10: Recommended operating conditions.
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 100mA below V
SS
or above V
DD
without latch-up.
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
100mA below V
SS
without latchup. These pins are not clamped to V
DD
.
(Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
SS
Negative Supply Current
CS High
q
10
15
mA
Nap Mode
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 5V
10
A
Sleep Mode
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 0V
1
A
P
DISS
Power Dissipation
q
80
120
mW
Nap Mode
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 5V
3.8
6
mW
Sleep Mode
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 0V
0.01
mW
5
LTC1409
Note 11: The falling CONVST edge starts a conversion. If CONVST returns
high at a critical point during the conversion it can create small errors. For
best results ensure that CONVST returns high either within 650ns after
conversion start or after BUSY rises.
TI I G CHARACTERISTICS
W U
Note 12: Signal-to-noise ratio (SNR) is measured at 100kHz and distortion
is measured at 400kHz. These results are used to calculate signal-to-noise
plus distortion (SINAD).
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
S/(N + D) vs Input Frequency
and Amplitude
INPUT FREQUENCY (Hz)
1k
SIGNAL/(NOISE + DISTORTION) (dB)
80
70
60
50
40
30
20
10
0
10k
100k
LTC1409 TPC01
1M
10M
V
IN
= 0dB
V
IN
= 20dB
V
IN
= 60dB
INPUT FREQUENCY (Hz)
1k
SIGNAL/(NOISE + DISTORTION) (dB)
80
70
60
50
40
30
20
10
0
10k
100k
LTC1409 TPC02
1M
10M
Signal-to-Noise Ratio vs
Input Frequency
Spurious-Free Dynamic Range vs
Input Frequency
INPUT FREQUENCY (Hz)
10k
SPURIOUS-FREE DYNAMIC RANGE (dB)
0
10
20
30
40
50
60
70
80
90
100
100k
1M
10M
LTC1409 TPC04
Distortion vs Input Frequency
INPUT FREQUENCY (Hz)
AMPLITUDE (dB BELOW THE FUNDAMENTAL)
0
10
20
30
40
50
60
70
80
90
100
1k
100k
1M
10M
LTC1409 TPC03
10k
THD
3RD
2ND
Intermodulation Distortion Plot
FREQUENCY (Hz)
0
AMPLITUDE (dB)
0
20
40
60
80
100
120
100k
200k
300k
400k
LTC1409 TPC05
50k
150k
250k
350k
fb fa
2fb fa
2fa fb
2fa
2fb
3fb
fa + 2fb
3fa
2fa
+ fb
f
SAMPLE
= 800kHz
f
IN1
= 88.19580078kHz
f
IN2
= 111.9995117kHz
fa + fb
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