LTC1415
12-Bit, 1.25Msps, 55mW
Sampling A/D Converter
FEATURES
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
1.25Msps Sample Rate
Single 5V Supply
Power Dissipation: 55mW
Nap and Sleep Power Shutdown Modes
±
0.35LSB INL and
±
0.25LSB DNL
72dB S/(N + D) and 80dB THD at 100kHz
External or Internal Reference Operation
True Differential Inputs Reject Common Mode Noise
Input Range: 4.096V (1mV/LSB)
28-Pin SSOP and SO Packages
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
µP
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.
APPLICATI
s
s
s
s
s
S
High Speed Data Acquisition
Imaging Systems
Digital Signal Processing
Multiplexed Data Acquisition Systems
Telecommunications
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
1.25MHz, 12-Bit Sampling A/D Converter
LTC1415
DIFFERENTIAL 1
AV
DD
+A
IN
ANALOG INPUT
(0V TO 4.096V) 2
–A
IN
DV
DD
2.50V 3 V
OV
DD
V
REF
OUTPUT 4
REF
REFCOMP
BUSY
5
AGND
CS
10µF
6
D11(MSB) CONVST
7
D10
RD
8
D9
SHDN
9
D8
NAP/SLP
10
D7
OGND
11
12-BIT
D6
D0
PARALLEL
12
D5
D1
BUS
13
D4
D2
14
DGND
D3
5V
28
27
26
25
24
23
22
21
20
19
18
17
16
15
µP
CONTROL
LINES
OUTPUT LOGIC
SUPPLY 3V OR 5V
10µF
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
12
11
10
9
NYQUIST
FREQUENCY
74
68
62
56
EFFECTIVE BITS
8
7
6
5
4
3
2
1
0
1k
10k
100k
INPUT FREQUENCY (Hz)
1M
2M
f
SAMPLE
= 1.25Msps
1415 TA01
U
SIGNAL/(NOISE + DISTORTION) (dB)
LTC1415 • TA02
UO
UO
1
LTC1415
ABSOLUTE
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
+A
IN
1
–A
IN
2
V
REF
3
REFCOMP 4
AGND 5
D11 (MSB) 6
D10 7
D9 8
D8 9
D7 10
D6 11
D5 12
D4 13
DGND 14
G PACKAGE
28-LEAD PLASTIC SSOP
28 AV
DD
27 DV
DD
26 OV
DD
25 BUSY
24 CS
23 CONVST
22 RD
21 SHDN
20 NAP/SLP
19 OGND
18 D0
17 D1
16 D2
15 D3
SW PACKAGE
28-LEAD PLASTIC SO WIDE
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
ORDER
PART NUMBER
LTC1415CG
LTC1415CSW
LTC1415IG
LTC1415ISW
T
JMAX
= 110°C,
θ
JA
= 95°C/W (G)
T
JMAX
= 110°C,
θ
JA
= 130°C/W (SW)
Consult factory for Military grade parts.
CO VERTER CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Linearity Error
Differential Linearity Error
Offset Error
Full-Scale Error
Full-Scale Tempco
With Internal Reference (Notes 5, 6)
MIN
q
CONDITIONS
(Note 7)
(Note 8)
q
q
q
TYP
0.35
0.25
±1
MAX
±1
±1
±6
±8
±20
UNITS
Bits
LSB
LSB
LSB
LSB
LSB
ppm/°C
12
I
OUT(REF)
= 0
±15
A ALOG I PUT
SYMBOL PARAMETER
V
IN
I
IN
C
IN
t
ACQ
t
AP
t
jitter
CMRR
(Note 5)
CONDITIONS
4.75V
≤
V
DD
≤
5.25V
CS = High
Between Conversions
During Conversions
q
q
q
MIN
TYP
4.096
MAX
±1
UNITS
V
µA
pF
pF
Analog Input Range (Note 9)
Analog Input Leakage Current
Analog Input Capacitance
Sample-and-Hold Acquisition Time
Sample-and-Hold Aperture Delay Time
Sample-and-Hold Aperture Delay Time Jitter
Analog Input Common Mode Rejection Ratio
19
5
50
–1.5
2
150
ps
RMS
dB
0V < V
CM
< V
DD
, DC to MHz
60
2
U
ns
ns
W
U
U
W W
W
U
U
U
LTC1415
DY A IC ACCURACY
SYMBOL
S/(N + D)
THD
SFDR
IMD
PARAMETER
I TER AL REFERE CE CHARACTERISTICS
PARAMETER
V
REF
Output Voltage
V
REF
Output Tempco
V
REF
Line Regulation
V
REF
Output Resistance
REFCOMP Output Voltage
CONDITIONS
I
OUT
= 0
I
OUT
= 0
4.75V
≤
V
DD
≤
5.25V
I
OUT
≤
0.1mA
DIGITAL I PUTS A D DIGITAL OUTPUTS
SYMBOL PARAMETER
V
IH
V
IL
I
IN
C
IN
V
OH
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
V
DD
= 4.75V
I
O
= – 10µA
I
O
= – 200µA
V
DD
= 4.75V
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
= 4.75V
V
IN
= 0V to V
DD
V
OL
Low Level Output Voltage
I
OZ
C
OZ
I
SOURCE
I
SINK
Hi-Z Output Leakage D11 to D0
Hi-Z Output Capacitance D11 to D0
Output Source Current
Output Sink Current
POWER REQUIRE E TS
SYMBOL PARAMETER
V
DD
I
DD
Supply Voltage
Supply Current
Nap Mode
Sleep Mode
Power Dissipation
Nap Mode
Sleep Mode
P
D
U W
U
U
U
W U
U
(Note 5)
CONDITIONS
100kHz Input Signal
600kHz Input Signal
100kHz Input Signal, First 5 Harmonics
600kHz Input Signal, First 5 Harmonics
600kHz Input Signal
f
IN1
= 29.37kHz, f
IN2
= 32.446kHz
S/(N + D)
≥
68dB
MIN
TYP
72
69
– 80
– 72
– 75
– 84
18
1
MAX
UNITS
dB
dB
dB
dB
dB
dB
MHz
MHz
Signal-to-(Noise + Distortion) Ratio
Total Harmonic Distortion
Spurious Free Dynamic Range
Intermodulation Distortion
Full-Power Bandwidth
Full-Linear Bandwidth
U
(Note 5)
MIN
2.480
TYP
2.500
±15
0.01
2
4.096
MAX
2.520
UNITS
V
ppm/°C
LSB/V
kΩ
V
I
OUT
= 0
(Note 5)
MIN
q
q
q
TYP
MAX
0.8
±10
UNITS
V
V
µA
pF
V
V
V
V
µA
pF
mA
mA
2.4
5
4.5
q
4.0
0.05
0.10
q
q
q
0.4
±10
15
– 10
10
(Note 5)
CONDITIONS
(Notes 10, 11)
CS High
SHDN = 0V, NAP/SLP = 5V (Note 12)
SHDN = 0V, NAP/SLP = 0V (Note 12)
CS High
SHDN = 0V, NAP/SLP = 5V
SHDN = 0V, NAP/SLP = 0V
q
q
MIN
4.75
TYP
11
1.5
1.0
55
7.5
0.01
MAX
5.25
20
2.3
100
12
UNITS
V
mA
mA
µA
mW
mW
mW
3
LTC1415
TI I G CHARACTERISTICS
SYMBOL
f
SAMPLE(MAX)
t
CONV
t
ACQ
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
t
10
PARAMETER
Maximum Sampling Frequency
Conversion and Acquisition Time
Conversion Time
Acquisition Time
CS to RD Setup Time
CS↓ to CONVST↓ Setup Time
NAP/SLP↑ to SHDN↓ Setup Time
t
11
t
12
t
13
t
14
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.
4
UW
(Note 5)
MIN
q
q
q
q
CONDITIONS
TYP
MAX
800
700
150
UNITS
MHz
ns
ns
ns
ns
ns
1.25
(Notes 9, 10)
(Notes 9, 10)
(Notes 9, 10)
q
q
0
10
200
200
10
ns
ns
ms
ns
ns
ns
ns
ns
ns
ns
SHDN↑ to CONVST↓ Wake-Up Time Nap Mode (Note 10)
Sleep Mode, C
REFCOMP
= 10µF (Note 10)
CONVST Low Time
CONVST to BUSY Delay
Data Ready Before BUSY↑
q
(Notes 10, 11)
C
L
= 25pF
q
q
50
10
60
20
15
50
–5
20
35
45
45
60
30
35
40
35
Delay Between Conversions
Wait Time RD↓ After BUSY↑
Data Access Time After RD↓
(Note 10)
C
L
= 25pF
q
q
q
ns
ns
ns
ns
ns
ns
ns
ns
ns
C
L
= 100pF
q
25
10
Bus Relinquish Time
0°C = T
A
= 70°C
– 40°C = T
A
= 85°C
RD Low Time
CONVST High Time
Aperture Delay of Sample-and-Hold
q
q
q
q
t
10
50
– 1.5
ns
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.
LTC1415
TYPICAL PERFORMANCE CHARACTERISTICS
S/(N + D) vs Input Frequency
and Amplitude
80
V
IN
= 0dB
SIGNAL/(NOISE + DISTORTION) (dB)
AMPLITUDE (dB BELOW THE FUNDAMENTAL)
70
SIGNAL-TO -NOISE RATIO (dB)
60
50
40
30
20
10
0
1k
V
IN
= –20dB
V
IN
= –60dB
10k
100k
INPUT FREQUENCY (Hz)
Spurious-Free Dynamic Range vs
Input Frequency
0
0
–20
–20
–30
–40
–50
–60
–70
–80
–90
10k
–120
100k
INPUT FREQUENCY (Hz)
1M
2M
AMPLITUDE (dB)
SPURIOUS-FREE DYNAMIC RANGE (dB)
–10
Integral Nonlinearity vs
Output Code
1.00
1.00
0.50
DNL ERROR (LSBs)
INL ERROR (LSBs)
0.00
–0.50
–1.00
0
512 1024 1536 2048 2560 3072 3584 4096
OUTPUT CODE
LTC1415 • TPC07
U W
LTC1415 • TPC01
LTC1415 • TPC04
Signal-to-Noise Ratio vs
Input Frequency
80
70
60
50
40
30
20
10
0
1M 2M
1k
10k
100k
INPUT FREQUENCY (Hz)
1M 2M
LTC1415 • TPC02
Distortion vs Input Frequency
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
1k
10k
100k
INPUT FREQUENCY (Hz)
1M 2M
LTC1415 • TPC03
THD
2ND
3RD
Intermodulation Distortion Plot
f
SAMPLE
= 1.25MHz
f
IN1
= 86.97509766kHz
f
IN2
= 113.2202148kHz
–40
fb – fa
–60
2fa – fb
–80
2fa
2fb – fa
fa + fb
2fb
3fa
2fa + fb
fa + 2fb
3fb
–100
0
100k
200k
300k
FREQUENCY (Hz)
400k
500k
600k
LTC1415 • TPC05
Differential Nonlinearity vs
Output Code
0.50
0.00
–0.50
–1.00
0
512 1024 1536 2048 2560 3072 3584 4096
OUTPUT CODE
LTC1415 • TPC06
5
嵌入式系统
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