1
LTC1415
12-Bit, 1.25Msps, 55mW
Sampling A/D Converter
U
A
O
PPLICATI
TYPICAL
1.25MHz, 12-Bit Sampling A/D Converter
, LTC and LT are registered trademarks of Linear Technology Corporation.
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
S
FEATURE
s
1.25Msps Sample Rate
s
Single 5V Supply
s
Power Dissipation: 55mW
s
Nap and Sleep Power Shutdown Modes
s
0.35LSB INL and
0.25LSB DNL
s
72dB S/(N + D) and 80dB THD at 100kHz
s
External or Internal Reference Operation
s
True Differential Inputs Reject Common Mode Noise
s
Input Range: 4.096V (1mV/LSB)
s
28-Pin SSOP and SO Packages
D
U
ESCRIPTIO
The LTC
1415 is a 700ns, 1.25Msps, 12-bit sampling
A/D converter that draws only 55mW from a single 5V
supply. This easy-to-use device includes a high dynamic
range sample-and-hold, precision reference and a trimmed
internal clock. Two power shutdown modes provide flex-
ibility for low power systems.
The LTC1415's full-scale input range is 4.096V. Low
linearity errors
0.35LSB INL,
0.25LSB DNL make it
ideal for imaging systems. Outstanding AC performance
includes 72dB S/(N + D) and 80dB THD with an input
frequency of 100kHz.
The unique differential input sample-and-hold can acquire
single-ended or differential input signals up to its 18MHz
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 data ready signal (BUSY)
ease connections to FIFOs, DSPs and microprocessors. A
separate output logic supply pin allows direct connection
to 3V components.
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
DV
DD
OV
DD
BUSY
CS
CONVST
RD
SHDN
NAP/SLP
OGND
D0
D1
D2
D3
LTC1415
10
F
DIFFERENTIAL
ANALOG INPUT
(0V TO 4.096V)
2.50V
V
REF
OUTPUT
10
F
5V
12-BIT
PARALLEL
BUS
P CONTROL
LINES
1415 TA01
OUTPUT LOGIC
SUPPLY 3V OR 5V
INPUT FREQUENCY (Hz)
1k
EFFECTIVE BITS
SIGNAL/(NOISE + DISTORTION) (dB)
12
11
10
9
8
7
6
5
4
3
2
1
0
74
68
62
56
10k
100k
LTC1415 TA02
1M
2M
NYQUIST
FREQUENCY
f
SAMPLE
= 1.25Msps
U
S
A
O
PPLICATI
s
High Speed Data Acquisition
s
Imaging Systems
s
Digital Signal Processing
s
Multiplexed Data Acquisition Systems
s
Telecommunications
2
LTC1415
AV
DD
= DV
DD
=OV
DD
= V
DD
(Notes 1, 2)
Supply Voltage (V
DD
) ................................................ 6V
Analog Input Voltage (Note 3) ...... 0.3V to V
DD
+ 0.3V
Digital Input Voltage (Note 4) .................. 0.3V to 12V
Digital Output Voltage .................... 0.3V to V
DD
+ 0.3V
Power Dissipation ............................................. 500mW
Operating Temperature Range
LTC1415C............................................... 0
C to 70
C
LTC1415I ........................................... 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
ORDER
PART NUMBER
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
q
12
Bits
Integral Linearity Error
(Note 7)
q
0.35
1
LSB
Differential Linearity Error
q
0.25
1
LSB
Offset Error
(Note 8)
1
6
LSB
q
8
LSB
Full-Scale Error
20
LSB
Full-Scale Tempco
I
OUT(REF)
= 0
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
q
4.096
V
I
IN
Analog Input Leakage Current
CS = High
q
1
A
C
IN
Analog Input Capacitance
Between Conversions
19
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
2
ps
RMS
CMRR
Analog Input Common Mode Rejection Ratio
0V < V
CM
< V
DD
, DC to MHz
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
DV
DD
OV
DD
BUSY
CS
CONVST
RD
SHDN
NAP/SLP
OGND
D0
D1
D2
D3
SW PACKAGE
28-LEAD PLASTIC SO WIDE
G PACKAGE
28-LEAD PLASTIC SSOP
TOP VIEW
Consult factory for Military grade parts.
LTC1415CG
LTC1415CSW
LTC1415IG
LTC1415ISW
T
JMAX
= 110
C,
JA
= 95
C/W (G)
T
JMAX
= 110
C,
JA
= 130
C/W (SW)
3
LTC1415
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
S/(N + D)
Signal-to-(Noise + Distortion) Ratio
100kHz Input Signal
72
dB
600kHz Input Signal
69
dB
THD
Total Harmonic Distortion
100kHz Input Signal, First 5 Harmonics
80
dB
600kHz Input Signal, First 5 Harmonics
72
dB
SFDR
Spurious Free Dynamic Range
600kHz Input Signal
75
dB
IMD
Intermodulation Distortion
f
IN1
= 29.37kHz, f
IN2
= 32.446kHz
84
dB
Full-Power Bandwidth
18
MHz
Full-Linear Bandwidth
S/(N + D)
68dB
1
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
V
REF
Output Resistance
I
OUT
0.1mA
2
k
REFCOMP Output Voltage
I
OUT
= 0
4.096
V
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
= 4.75V
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
Hi-Z Output Leakage D11 to D0
V
OUT
= 0V to V
DD
, CS High
q
10
A
C
OZ
Hi-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
POWER REQUIRE E TS
W U
(Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
DD
Supply Voltage
(Notes 10, 11)
4.75
5.25
V
I
DD
Supply Current
CS High
q
11
20
mA
Nap Mode
SHDN = 0V, NAP/SLP = 5V (Note 12)
q
1.5
2.3
mA
Sleep Mode
SHDN = 0V, NAP/SLP = 0V (Note 12)
1.0
A
P
D
Power Dissipation
CS High
55
100
mW
Nap Mode
SHDN = 0V, NAP/SLP = 5V
7.5
12
mW
Sleep Mode
SHDN = 0V, NAP/SLP = 0V
0.01
mW
(Note 5)
(Note 5)
I TER AL REFERE CE CHARACTERISTICS
U
U
U
4
LTC1415
(Note 5)
TI I G CHARACTERISTICS
W U
The
q
denotes 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 ground or above V
DD
,
they will be clamped by internal diodes. This product can handle input
currents greater than 100mA below ground or above V
DD
without latchup.
Note 4: When these pin voltages are taken below ground, they will be
clamped by internal diodes. This product can handle input currents greater
than 100mA below ground without latchup. These pins are not clamped
to V
DD
.
Note 5: V
DD
= 5V, f
SAMPLE
= 1.25MHz, 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.
Note 11: The falling edge of CONVST starts a conversion. If CONVST
returns high at a critical point during the conversion it can create small
errors. For best performance ensure that CONVST returns high either
within 425ns after the start of the conversion or after BUSY rises.
Note 12: CS = RD = CONVST = 0V.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
SAMPLE(MAX)
Maximum Sampling Frequency
q
1.25
MHz
Conversion and Acquisition Time
q
800
ns
t
CONV
Conversion Time
q
700
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)
200
ns
t
4
SHDN
to CONVST
Wake-Up Time
Nap Mode (Note 10)
200
ns
Sleep Mode, C
REFCOMP
= 10
F (Note 10)
10
ms
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
50
ns
t
9
Wait Time RD
After BUSY
q
5
ns
t
10
Data Access Time After RD
C
L
= 25pF
20
35
ns
q
45
ns
C
L
= 100pF
25
45
ns
q
60
ns
t
11
Bus Relinquish Time
10
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
5
LTC1415
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
INPUT FREQUENCY (Hz)
SIGNAL/(NOISE + DISTORTION) (dB)
80
70
60
50
40
30
20
10
0
1k
100k
1M
2M
LTC1415 TPC01
10k
V
IN
= 0dB
V
IN
= 20dB
V
IN
= 60dB
S/(N + D) vs Input Frequency
and Amplitude
INPUT FREQUENCY (Hz)
AMPLITUDE (dB BELOW THE FUNDAMENTAL)
0
10
20
30
40
50
60
70
80
90
100
LTC1415 TPC03
THD
2ND
3RD
1k
100k
1M
2M
10k
Distortion vs Input Frequency
INPUT FREQUENCY (Hz)
SIGNAL-TO -NOISE RATIO (dB)
80
70
60
50
40
30
20
10
0
1k
LTC1415 TPC02
100k
1M
2M
10k
Signal-to-Noise Ratio vs
Input Frequency
Spurious-Free Dynamic Range vs
Input Frequency
Intermodulation Distortion Plot
INPUT FREQUENCY (Hz)
10k
SPURIOUS-FREE DYNAMIC RANGE (dB)
0
10
20
30
40
50
60
70
80
90
100k
1M
2M
LTC1415 TPC04
FREQUENCY (Hz)
0
AMPLITUDE (dB)
0
20
40
60
80
100
120
200k
300k
600k
LTC1415 TPC05
100k
400k
500k
fb fa
2fb fa
2fa fb
2fa
2fb
3fb
fa + 2fb
3fa
2fa
+ fb
fa + fb
f
SAMPLE
= 1.25MHz
f
IN1
= 86.97509766kHz
f
IN2
= 113.2202148kHz
Integral Nonlinearity vs
Output Code
OUTPUT CODE
0
INL ERROR (LSBs)
1.00
0.50
0.00
0.50
1.00
512 1024 1536
LTC1415 TPC07
2048 2560 3072 3584 4096
Differential Nonlinearity vs
Output Code
OUTPUT CODE
0
DNL ERROR (LSBs)
1.00
0.50
0.00
0.50
1.00
512 1024 1536
LTC1415 TPC06
2048 2560 3072 3584 4096
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