LTC1409
12-Bit, 800ksps Sampling
A/D Converter with Shutdown
FEATURES
s
s
s
s
s
s
DESCRIPTIO
s
s
s
s
Sample Rate: 800ksps
Power Dissipation: 80mW
72.5dB S/(N + D) and 86dB THD at Nyquist
No Pipeline Delay
Nap (4mW) and Sleep (10µW) Shutdown Modes
Operates with Internal 15ppm/°C Reference
or External Reference
True Differential Inputs Reject Common Mode Noise
20MHz Full Power Bandwidth Sampling
±2.5V
Bipolar Input Range
28-Pin SO Wide and SSOP Package
The LTC
®
1409 is a 1µs, 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
µP
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.
APPLICATI
s
s
s
s
s
s
S
Telecommunications
Digital Signal Processing
Multiplexed Data Acquisition Systems
High Speed Data Acquisition
Spectrum Analysis
Imaging Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
800kHz, 12-Bit Sampling A/D Converter
LTC1409
DIFFERENTIAL 1
AV
DD
+A
IN
ANALOG INPUT
(–2.5V TO 2.5V) 2
–A
IN
OV
DD
2.50V 3 V
V
SS
V
REF
OUTPUT 4
REF
REFCOMP
BUSY
5
10µF
AGND
CS
6
D11(MSB) CONVST
7
D10
RD
8
D9
SHDN
9
D8
NAP/SLP
10
D7
OGND
12-BIT
11
D6
D0
PARALLEL
12
BUS
D5
D1
13
D4
D2
14
DGND
D3
5V
28
27
26
25
24
23
22
21
20
19
18
17
16
15
µP
CONTROL
LINES
–5V
10µF
Effective Bits and Signal-to-(Noise + Distortion)
vs Input Frequency
12
10
10µF
EFFECTIVE BITS
8
6
4
2
0
1k
f
SAMPLE
= 800ksps
10k
100k
1M
INPUT FREQUENCY (Hz)
LTC1409 • TA01
U
74
68
NYQUIST
FREQUENCY
62
56
50
S/(N + D) (dB)
UO
UO
10M
LTC1409 • TA02
1
LTC1409
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 SO
28 AV
DD
27 OV
DD
26 V
SS
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
= 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
ORDER
PART NUMBER
LTC1409CG
LTC1409CSW
LTC1409IG
LTC1409ISW
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
I
OUT(REF)
= 0
(Note 8)
(Note 7)
CONDITIONS
With Internal Reference (Notes 5, 6)
MIN
q
q
q
q
TYP
±0.3
±0.3
±2
MAX
±1
±1
±6
±8
±15
UNITS
Bits
LSB
LSB
LSB
LSB
LSB
ppm/°C
12
q
±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, – 5.25V
≤
V
SS
≤
– 4.75V
CS = High
Between Conversions
During Conversions
q
q
q
MIN
TYP
±2.5
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
17
5
50
–1.5
5
150
ps
RMS
dB
– 2.5V < (–A
IN
= +A
IN
) < 2.5V
60
2
U
ns
ns
W
U
U
W W
W
U
U
U
LTC1409
DY A IC ACCURACY
SYMBOL
S/(N + D)
THD
PARAMETER
IMD
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
– 5.25V
≤
V
SS
≤
– 4.75V
– 0.1mA
≤
|
I
OUT
|
≤
0.1mA
I
OUT
= 0
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
High-Z Output Leakage D11 to D0
High-Z Output Capacitance D11 to D0
Output Source Current
Output Sink Current
POWER REQUIRE E TS
SYMBOL PARAMETER
V
DD
V
SS
I
DD
Positive Supply Voltage
Negative Supply Voltage
Positive Supply Current
Nap Mode
Sleep Mode
U W
U
U
U
W U
U
(Note 5)
CONDITIONS
q
q
q
q
MIN
70
68
TYP
73.0
72.5
– 90
– 86
– 90
– 84
15
1.6
MAX
UNITS
dB
dB
Signal-to-Noise Plus Distortion Ratio 100kHz Input Signal (Note 12)
400kHz Input Signal (Note 12)
Total Harmonic Distortion
Peak Harmonic or Spurious Noise
Intermodulation Distortion
Full Power Bandwidth
Full Linear Bandwidth
S/(N + D)
≥
68dB
100kHz Input Signal, First Five Harmonics
400kHz Input Signal, First Five Harmonics
400kHz Input Signal
f
IN1
= 29.37kHz, f
IN2
= 32.446kHz
– 74
– 74
dB
dB
dB
dB
MHz
MHz
U
(Note 5)
MIN
2.480
TYP
2.500
±15
0.01
0.01
4
4.06
MAX
2.520
UNITS
V
ppm/°C
LSB/V
LSB/V
kΩ
V
(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)
MIN
4.75
– 4.75
6.0
0.8
1.0
TYP
MAX
5.25
– 5.25
9.0
1.2
UNITS
V
V
mA
mA
µA
CONDITIONS
(Notes 10, 11)
(Note 10)
CS High
q
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 5V
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 0V
3
LTC1409
POWER REQUIRE E TS
SYMBOL PARAMETER
I
SS
Negative Supply Current
Nap Mode
Sleep Mode
Power Dissipation
Nap Mode
Sleep Mode
P
DISS
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 Time
Acquisition Time
CS to RD Setup Time
CS↓ to CONVST↓ Setup Time
NAP/SLP↓ to SHDN↓ Setup Time
CONVST Low Time
CONVST to BUSY Delay
Data Ready Before BUSY↑
SHDN↑ to CONVST↓ Wake-Up Time (Note 10)
(Notes 10, 11)
C
L
= 25pF
q
q
q
Delay Between Conversions
Wait Time RD↓ After BUSY↑
Data Access Time After RD↓
t
11
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
12
t
13
t
14
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
.
4
U W
(Note 5)
MIN
TYP
10
10
1
80
3.8
0.01
MAX
15
UNITS
mA
µA
µA
mW
mW
mW
CONDITIONS
CS High
q
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 5V
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 0V
q
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 5V
CONVST = CS = RD = SHDN = 0V, NAP/SLP = 0V
120
6
UW
(Note 5)
MIN
q
q
q
CONDITIONS
TYP
900
MAX
1250
150
UNITS
kHz
ns
ns
ns
ns
ns
800
(Notes 9, 10)
(Notes 9, 10)
(Notes 9, 10)
q
q
q
0
10
10
200
50
10
60
20
15
40
–5
15
35
45
45
60
30
35
40
35
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
(Note 10)
C
L
= 25pF
q
q
q
C
L
= 100pF
q
20
8
t
10
50
– 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.
LTC1409
TI I G CHARACTERISTICS
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.
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 PERFORMANCE CHARACTERISTICS
S/(N + D) vs Input Frequency
and Amplitude
80
80
SIGNAL/(NOISE + DISTORTION) (dB)
AMPLITUDE (dB BELOW THE FUNDAMENTAL)
SIGNAL/(NOISE + DISTORTION) (dB)
70
60
50
40
30
20
10
0
1k
V
IN
= 0dB
V
IN
= 20dB
V
IN
= 60dB
1M
10k
100k
INPUT FREQUENCY (Hz)
Spurious-Free Dynamic Range vs
Input Frequency
0
0
–20
SPURIOUS-FREE DYNAMIC RANGE (dB)
–10
–20
–40
–50
–60
–70
–80
–90
–100
10k
AMPLITUDE (dB)
–30
100k
1M
INPUT FREQUENCY (Hz)
U W
UW
Signal-to-Noise Ratio vs
Input Frequency
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
70
60
50
40
30
20
10
0
10M
1k
1M
10k
100k
INPUT FREQUENCY (Hz)
10M
Distortion vs Input Frequency
3RD
THD
2ND
100k
1M
10k
INPUT FREQUENCY (Hz)
10M
1k
LTC1409 • TPC01
LTC1409 • TPC02
LTC1409 • TPC03
Intermodulation Distortion Plot
f
SAMPLE
= 800kHz
f
IN1
= 88.19580078kHz
f
IN2
= 111.9995117kHz
–40
–60
–80
fb – fa
2fa – fb
2fb – fa
2fa
fa + fb
2fb
2fa + fb
3fa
fa + 2fb
3fb
–100
–120
10M
LTC1409 • TPC04
0
50k
100k
150k
200k
FREQUENCY (Hz)
250k
300k
350k
400k
LTC1409 • TPC05
5
嵌入式系统
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