1
LTC1740
1740f
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
BLOCK DIAGRA
W
14-Bit, 6Msps,
Sampling ADC
The LTC
1740 is a 6Msps, 14-bit sampling A/D converter
that draws only 245mW from either a single 5V or dual
5V supplies. This easy-to-use device includes a high
dynamic range sample-and-hold and a programmable
precision reference.
The LTC1740 has a flexible input circuit that allows differ-
ential full-scale input ranges of
2.5V and
1.25V with the
internal reference, or any full-scale input range up to
2.5V with an external reference. The input common
mode voltage is arbitrary, though a 2.5V reference is
provided for single supply applications.
DC specifications include 1LSB typical INL, 0.5LSB typical
DNL and no missing codes over temperature. Outstanding
AC performance includes 79dB S/(N + D) and 91dB SFDR
at an input frequency of 2.5MHz.
The unique differential input sample-and-hold can acquire
single-ended or differential input signals up to its 80MHz
bandwidth. The 75dB common mode rejection allows
users to eliminate ground loops and common mode noise
by measuring signals differentially from the source. A
separate output logic supply allows direct connection to
3V components.
s
6Msps Sample Rate
s
79dB S/(N + D) and 91dB SFDR at 2.5MHz f
IN
s
Single 5V Supply or
5V Supplies
s
Integral Nonlinearity Error: < 1LSB
s
Differential Nonlinearity: < 0.5LSB
s
80MHz Full-Power Bandwidth Sampling
s
2.5V and
1.25V Bipolar Input Ranges
s
2.5V Signal Ground Available
s
Out-of-Range Indicator
s
True Differential Inputs with 75dB CMRR
s
Power Dissipation: 245mW
s
36-Pin SSOP Package (0.209 Inch Width)
s
Telecommunications
s
Multiplexed Data Acquisition Systems
s
High Speed Data Acquisition
s
Spectral Analysis
s
Imaging Systems
4096-Point FFT
, LTC and LT are registered trademarks of Linear Technology Corporation.
DIGITAL CORRECTION
LOGIC
1740 TA01
MODE SELECT
PIPELINED 14-BIT ADC
S/H
1
F
1
F
0V OR 5V
1
F
1000pF
+
V
IN
V
CM
1
F
5V
3V TO 5V
V
DD
1
F
OV
DD
OGND
OF
D13 (MSB)
6MHz CLK
DIGITAL
OUTPUT
SENSE
V
REF
A
IN
+
A
IN
V
SS
GND
2.250V
2.5V
REFERENCE
1
19
32
V
DD
33
1
F
5V
V
DD
8
V
DD
9
2
3
4
5
30
V
SS
29
6
GND
7
GND
10
GND
34
GND
31
11
OGND
CLK
28
35
36
12
D7
D6
18
20
D0 (LSB)
BUSY
26
27
OUTPUT
BUFFERS
FREQUENCY (MHz)
0
120
AMPLITUDE (dB)
100
80
60
40
0
0.5
1.0
1.5
2.0
1740 TA02
2.5
3.0
20
f
SMPL
= 6MHz
f
IN
= 2.5MHz, 5V
P-P
5V SUPPLY
2
LTC1740
1740f
0V
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 3) ......................... (V
SS
0.3V) to (V
DD
+ 0.3V)
Digital Output Voltage ........ (V
SS
0.3V) to (V
DD
+ 0.3V)
Power Dissipation .............................................. 500mW
Operating Temperature Range
LTC1740C ............................................... 0
C to 70
C
LTC1740I ............................................ 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
q
14
Bits
Integral Linearity Error
(Note 6)
1
2.5
LSB
Differential Linearity Error
q
1
0.5
1.25
LSB
Offset Error
(Note 7)
15
60
LSB
q
80
LSB
Full-Scale Error
30
75
LSB
Full-Scale Tempco
I
OUT(REF)
= 0
15
ppm/
C
ORDER PART
NUMBER
LTC1740CG
LTC1740IG
T
JMAX
= 125
C,
JA
= 95
C/W
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
TOP VIEW
G PACKAGE
36-LEAD PLASTIC SSOP
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
+A
IN
A
IN
V
CM
SENSE
V
REF
GND
GND
V
DD
V
DD
GND
OGND
D13 (MSB)
D12
D11
D10
D9
D8
D7
OF
CLK
GND
V
DD
V
DD
GND
V
SS
V
SS
OGND
BUSY
D0
D1
D2
D3
D4
D5
D6
OV
DD
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. With internal 4.500V reference. Specifications are guaranteed for both
dual supply and single supply operation. (Notes 4, 5)
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
CO VERTER CHARACTERISTICS
U
Consult LTC Marketing for parts specified with wider operating temperature
ranges.
3
LTC1740
1740f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
S/(N + D)
Signal-to-Noise Plus Distortion Ratio
1MHz Input Signal
79.1
dB
2.5MHz Input Signal
79.0
dB
THD
Total Harmonic Distortion
1MHz Input Signal, First 5 Harmonics
90
dB
2.5MHz Input Signal, First 5 Harmonics
89
dB
SFDR
Spurious Free Dynamic Range
1MHz Input Signal
92
dB
2.5MHz Input Signal
91
dB
Full-Power Bandwidth
80
MHz
Input Referred Noise
0.45
LSB
RMS
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CM
Output Voltage
I
OUT
= 0
2.475
2.500
2.525
V
V
CM
Output Tempco
I
OUT
= 0
15
ppm/
C
V
CM
Line Regulation
4.75V
V
DD
5.25V
0.6
mV/V
5.25V
V
SS
4.75V
0.03
mV/V
V
CM
Output Resistance
0.1mA
I
OUT
0.1mA
8
V
REF
Output Voltage
SENSE = GND, I
OUT
= 0
4.500
V
SENSE = V
REF
, I
OUT
= 0
2.250
V
SENSE = V
DD
Drive V
REF
with
V
External Reference
V
REF
Output Tempco
15
ppm/
C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Analog Input Range
V
REF
= 4.5V (SENSE = 0V)
q
2.50
V
V
REF
= 2.25V (SENSE Tied to V
REF
)
q
1.25
V
External V
REF
(SENSE = 5V)
q
V
REF
/1.8
V
I
IN
Analog Input Leakage Current
q
10
A
C
IN
Analog Input Capacitance
Between Conversions
12
pF
During Conversions
4
pF
t
ACQ
Sample-and-Hold Acquisition Time
67
ns
t
AP
Sample-and-Hold Aperture Delay Time
900
ps
t
jitter
Sample-and-Hold Aperture Delay Time Jitter
0.6
ps
RMS
CMRR
Analog Input Common Mode Rejection Ratio
V
SS
< (A
IN
= +A
IN
) < V
DD
75
dB
The
q
denotes specifications which apply over the full operating temperature range, otherwise
specifications are at T
A
= 25
C. Specifications are guaranteed for both dual supply and single supply operation. (Note 4)
V
DD
= OV
DD
= 5V, V
SS
= 0V, V
REF
= 4.5V, A
IN
= 0.1dBFS, AC coupled differential input.
T
A
= 25
C. Specifications are guaranteed for both dual supply and single supply operation. (Note 4)
A ALOG I PUT
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DY
A
IC ACCURACY
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I TER AL REFERE CE CHARACTERISTICS
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4
LTC1740
1740f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
V
DD
= 5.25V, V
SS
= 0V
q
2.4
V
V
DD
= 5.25V, V
SS
= 5V
q
2.4
V
V
IL
Low Level Input Voltage
V
DD
= 4.75V, V
SS
= 0V
q
0.8
V
V
DD
= 4.75V, V
SS
= 5V
q
0.8
V
I
IN
Digital Input Current
V
IN
= 0V to V
DD
q
10
A
C
IN
Digital Input Capacitance
1.8
pF
V
OH
High Level Output Voltage
0V
DD
= 4.75V, I
O
= 10
A
4.74
V
0V
DD
= 4.75V, I
O
= 200
A
q
4.0
4.71
V
0V
DD
= 2.7V, I
O
= 10
A
2.6
V
0V
DD
= 2.7V, I
O
= 200
A
q
2.3
V
V
OL
Low Level Output Voltage
0V
DD
= 4.75V, I
O
= 160
A
0.05
V
0V
DD
= 4.75V, I
O
= 1.6mA
q
0.10
0.4
V
0V
DD
= 2.7V, I
O
= 160
A
0.05
V
0V
DD
= 2.7V, I
O
= 1.6mA
q
0.10
0.4
V
I
SOURCE
Output Source Current
V
OUT
= 0V, 0V
DD
= 5V
50
mA
I
SINK
Output Sink Current
V
OUT
= V
DD
, 0V
DD
= 5V
35
mA
The
q
denotes specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25
C. Specifications are guaranteed for both dual supply and single
supply operation. (Note 4)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
DD
Positive Supply Voltage
(Note 9)
4.75
5.25
V
OV
DD
Output Supply Voltage
(Note 9)
2.7
V
DD
V
V
SS
Negative Supply Voltage
Dual Supply Mode
5.25
4.75
V
Single Supply Mode
0
V
I
DD
Positive Supply Current
q
47
60
mA
I
SS
Negative Supply Current
q
2.3
2.6
mA
P
D
Power Dissipation
q
245
300
mW
The
q
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25
C. Specifications are guaranteed for both dual supply and single supply operation. (Note 4)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
SAMPLE
Sampling Frequency
q
0.05
6
MHz
t
CONV
Conversion Time
q
100
135
ns
t
ACQ
Acquisition Time
(Note 9)
q
31
67
ns
t
H
CLK High Time
(Note 9)
q
20
83.3
ns
t
L
CLK Low Time
(Note 9)
q
20
83.3
ns
t
AP
Aperature Delay of Sample-and-Hold
900
ps
t
1
CLK
to BUSY
3.5
ns
t
2
BUSY
to Outputs Valid
1.5
ns
Data Latency
3
Cycles
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. Specifications are guaranteed for both dual supply and single supply operation.
(Note 4)
DIGITAL I PUTS A D DIGITAL OUTPUTS
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POWER REQUIRE E TS
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TI I G CHARACTERISTICS
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5
LTC1740
1740f
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 GND and OGND
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 latchup.
Note 4: V
DD
= 5V, V
SS
= 5V or 0V, f
SAMPLE
= 6MHz, t
r
= t
f
= 5ns unless
otherwise specified.
Note 5: Linearity, offset and full-scale specifications apply for a
single-ended +A
IN
input with A
IN
tied to V
CM
for single supply and 0V for
dual supply.
Note 6: 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 7: Bipolar offset is the offset voltage measured from 0.5LSB
when the output code flickers between 00 0000 0000 0000 and
11 1111 1111 1111.
Note 8: Guaranteed by design, not subject to test.
Note 9: Recommended operating conditions.
TI I G CHARACTERISTICS
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TYPICAL PERFOR A CE CHARACTERISTICS
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Typical INL at 6Msps
Typical DNL at 6Msps
S/(N + D) vs Input Frequency
and Amplitude
CODE
0
INL (LSB)
0
0.5
1.0
16384
1740 G01
0.5
1.0
2.0
4096
8192
12288
1.5
2.0
1.5
CODE
0
1.0
DNL (LSB)
0.8
0.4
0.2
0
1.0
0.4
4096
8192
1740 G02
0.6
0.6
0.8
0.2
12288
16384
INPUT FREQUENCY (MHz)
0.1
50
S/(N + D) (dBc)
55
60
65
70
80
1
10
1740 G03
100
75
V
IN
= 0dBFS
V
IN
= 6dBFS
V
IN
= 20dBFS
DUAL SUPPLIES
5V INPUT RANGE
DIFFERENTIAL INPUT
6Msps
S/(N + D) vs Input Frequency
and Amplitude
INPUT FREQUENCY (MHz)
0.1
50
S/(N + D) (dBc)
55
60
65
70
80
1
10
1740 G04
100
75
V
IN
= 0dBFS
V
IN
= 6dBFS
V
IN
= 20dBFS
SINGLE SUPPLY
5V INPUT RANGE
DIFFERENTIAL INPUT
6Msps
SFDR and THD
vs Input Frequency
INPUT FREQUENCY (MHz)
0.1
50
AMPLITUDE (dB)
55
65
70
75
10
95
1740 G05
60
1
100
80
85
90
SFDR
THD
DUAL SUPPLIES
5V INPUT RANGE
A
IN
= 0dBFS
DIFFERENTIAL INPUT
6Msps
INPUT FREQUENCY (MHz)
0.1
50
AMPLITUDE (dB)
55
65
70
75
10
95
1740 G06
60
1
100
80
85
90
SFDR
THD
SINGLE SUPPLY
5V INPUT RANGE
A
IN
= 0dBFS
DIFFERENTIAL INPUT
6Msps
SFDR and THD
vs Input Frequency
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