1
LTC1400
Complete SO-8, 12-Bit,
400ksps ADC with Shutdown
The LTC
1400 is a complete 400ksps, 12-bit A/D con-
verter which draws only 75mW from a 5V or
5V supplies.
This easy-to-use device comes complete with a 200ns
sample-and-hold and a precision reference. Unipolar and
bipolar conversion modes add to the flexibility of the ADC.
The LTC1400 has two power saving modes: Nap and
Sleep. In Nap mode, it consumes only 6mW of power and
can wake up and convert immediately. In the Sleep mode,
it consumes 30
W of power typically. Upon power-up
from Sleep mode, a reference ready (REFRDY) signal is
available in the serial data word to indicate that the
reference has settled and the chip is ready to convert.
The LTC1400 converts 0V to 4.096V unipolar inputs from
a single 5V supply and
2.048V bipolar inputs from
5V
supplies. Maximum DC specs include
1LSB INL,
1LSB
DNL and 45ppm/
C drift over temperature. Guaranteed AC
performance includes 70dB S/(N + D) and 76dB THD at
an input frequency of 100kHz, over temperature.
The 3-wire serial port allows compact and efficient data
transfer to a wide range of microprocessors, microcontrollers
and DSPs.
DESCRIPTIO
N
U
FEATURES
s
Complete 12-Bit ADC in SO-8
s
Single Supply 5V or
5V Operation
s
Sample Rate: 400ksps
s
Power Dissipation: 75mW (Typ)
s
72dB S/(N + D) and 80dB THD at Nyquist
s
No Missing Codes over Temperature
s
Nap Mode with Instant Wake-Up: 6mW
s
Sleep Mode: 30
W
s
High Impedance Analog Input
s
Input Range (1mV/LSB): 0V to 4.096 or
2.048V
s
Internal Reference Can Be Overdriven Externally
s
3-Wire Interface to DSPs and Processors (SPI and
MICROWIRE
TM
Compatible)
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corp.
s
High Speed Data Acquisition
s
Digital Signal Processing
s
Multiplexed Data Acquisition Systems
s
Audio and Telecom Processing
s
Digital Radio
s
Spectrum Analysis
s
Low Power and Battery-Operated Systems
s
Handheld or Portable Instruments
APPLICATIO
N
S
U
Single 5V Supply, 400kHz, 12-Bit Sampling A/D Converter
TYPICAL APPLICATIO
N
U
V
CC
A
IN
V
REF
GND
V
SS
CONV
CLK
D
OUT
MPU
P1.4
P1.3
P1.2
LTC1400
+
0.1
F
10
F
+
0.1
F
10
F
2.42V REF
OUT
ANALOG INPUT
(0V TO 4.096V)
4
3
2
1
5
6
7
8
SERIAL
DATA LINK
5V
LTC1400 TA01
Power Consumption vs Sample Rate
SAMPLE RATE (Hz)
0.01
SUPPLY CURRENT (mA)
100
10
1
0.1
0.01
0.001
10
1k
1M
LTC1400 TA02
0.1
1
100
10k 100k
NORMAL CONVERSION
NAP MODE
BETWEEN CONVERSION
SLEEP AND NAP MODE
BETWEEN CONVERSION
SLEEP MODE BETWEEN
CONVERSION
6.4MHz CLOCK
2
LTC1400
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
(Notes 1, 2)
Supply Voltage (V
CC
) ................................................. 7V
Negative Supply Voltage (V
SS
).................... 6V to GND
Total Supply Voltage (V
CC
to V
SS
)
Bipolar Operation Only ........................................ 12V
Analog Input Voltage (Note 3)
Unipolar Operation .................. 0.3V to (V
CC
+ 0.3V)
Bipolar Operation........... (V
SS
0.3V) to (V
CC
+ 0.3V)
Digital Input Voltage (Note 4)
Unipolar Operation ................................ 0.3V to 12V
Bipolar Operation.........................(V
SS
0.3V) to 12V
Digital Output Voltage
Unipolar Operation .................. 0.3V to (V
CC
+ 0.3V)
Bipolar Operation........... (V
SS
0.3V) to (V
CC
+ 0.3V)
Power Dissipation .............................................. 500mW
Operation Temperature Range
LTC1400C................................................ 0
C to 70
C
LTC1400I ............................................ 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
LTC1400CS8
LTC1400IS8
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Positive Supply Voltage (Note 6)
Unipolar
4.75
5.25
V
Bipolar
4.75
5.25
V
V
SS
Negative Supply Voltage (Note 6)
Bipolar Only
2.45
5.25
V
I
CC
Positive Supply Current
f
SAMPLE
= 400ksps
q
15
30
mA
Nap Mode
q
1.0
3.0
mA
Sleep Mode
q
5.0
20.0
A
I
SS
Negative Supply Current
f
SAMPLE
= 400ksps, V
SS
= 5V
q
0.3
0.6
mA
Nap Mode
q
0.2
0.5
mA
Sleep Mode
q
1
5
A
P
D
Power Dissipation
f
SAMPLE
= 400ksps
q
75
160
mW
Nap Mode
q
6
20
mW
Sleep Mode
q
30
125
W
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Analog Input Range (Note 7)
4.75V
V
CC
5.25V (Unipolar)
q
0 to 4.096
V
4.75V
V
CC
5.25V, 5.25V
V
SS
2.45V (Bipolar)
q
2.048
V
I
IN
Analog Input Leakage Current
During Conversions (Hold Mode)
q
1
A
C
IN
Analog Input Capacitance
Between Conversions (Sample Mode)
45
pF
During Conversions (Hold Mode)
5
pF
PUT
U
I
A
A
U
LOG
(Note 5)
POWER REQUIRE E TS
W
U
(Note 5)
ORDER PART
NUMBER
S8 PART MARKING
1400
1400I
T
JMAX
= 150
C,
JA
= 130
C/ W
TOP VIEW
V
CC
A
IN
V
REF
GND
V
SS
CONV
CLK
D
OUT
S8 PACKAGE
8-LEAD PLASTIC SO
1
2
3
4
8
7
6
5
Consult factory for PDIP packages and Military grade parts.
3
LTC1400
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
q
12
Bits
Integral Linearity Error
(Note 9)
q
1
LSB
Differential Linearity Error
q
1
LSB
Offset Error
(Note 10)
6
LSB
q
8
LSB
Full-Scale Error
15
LSB
Full-Scale Tempco
I
OUT(REF)
= 0
q
10
45
ppm/
C
With internal reference (Notes 5, 8)
C
C
HARA TERISTICS
CO
U
VERTER
I TER AL REFERE CE CHARACTERISTICS
U
U
U
V
CC
= 5V, V
SS
= 5V, f
SAMPLE
= 400kHz
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
S/(N + D) Signal-to-Noise
100kHz Input Signal Commercial
q
70
72
dB
Plus Distortion Ratio
Industrial
q
69
dB
200kHz Input Signal
72
dB
THD
Total Harmonic Distortion
100kHz Input Signal
q
82
76
dB
Up to 5th Harmonic
200kHz Input Signal
80
dB
Peak Harmonic or
100kHz Input Signal
q
84
76
dB
Spurious Noise
200kHz Input Signal
82
dB
IMD
Intermodulation Distortion
f
IN1
= 99.51kHz, f
IN2
= 102.44kHz
82
dB
f
IN1
= 199.12kHz, f
IN2
= 202.05kHz
70
dB
Full Power Bandwidth
4
MHz
Full Linear Bandwidth (S/(N + D)
68dB)
900
kHz
ACCURACY
IC
DY
U
W
A
(Note 5)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
REF
Output Voltage
I
OUT
= 0
2.400
2.420
2.440
V
V
REF
Output Tempco
I
OUT
= 0
q
10
45
ppm/
C
V
REF
Line Regulation
4.75V
V
CC
5.25V
0.01
LSB/ V
5.25V
V
SS
0V
0.01
LSB/ V
V
REF
Load Regulation
0
I
OUT
1mA
2
LSB/mA
V
REF
Wake-Up Time from Sleep Mode (Note 7)
C
VREF
= 10
F
4
ms
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
V
CC
= 5.25V
q
2.0
V
V
IL
Low Level Input Voltage
V
CC
= 4.75V
q
0.8
V
I
IN
Digital Input Current
V
IN
= 0V to V
CC
q
10
A
C
IN
Digital Input Capacitance
5
pF
V
OH
High Level Output Voltage
V
CC
= 4.75V, I
O
= 10
A
4.7
V
V
CC
= 4.75V, I
O
= 200
A
q
4.0
V
V
OL
Low Level Output Voltage
V
CC
= 4.75V, I
O
= 160
A
0.05
V
V
CC
= 4.75V, I
O
= 1.6mA
q
0.10
0.4
V
(Note 5)
DIGITAL I PUTS A
N
D OUTPUTS
U
U
4
LTC1400
(Note 5)
DIGITAL I PUTS A
N
D OUTPUTS
U
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
OZ
Hi-Z Output Leakage D
OUT
V
OUT
= 0V to V
CC
q
10
A
C
OZ
Hi-Z Output Capacitance D
OUT
(Note 7)
15
pF
I
SOURCE
Output Source Current
V
OUT
= 0
10
mA
I
SINK
Output Sink Current
V
OUT
= V
CC
10
mA
TI I G CHARACTERISTICS
W U
(Note 5)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
SAMPLE(MAX)
Maximum Sampling Frequency
(Note 6)
q
400
kHz
t
CONV
Conversion Time
f
CLK
= 6.4MHz
q
2.1
s
t
ACQ
Acquisition Time (Unipolar Mode)
(Note 7)
q
230
300
ns
(Bipolar Mode V
SS
= 5V)
q
200
270
ns
f
CLK
CLK Frequency
q
0.1
6.4
MHz
t
CLK
CLK Pulse Width
(Note 7)
q
50
ns
t
WK(NAP)
Time to Wake Up from Nap Mode
(Note 7)
350
ns
t
1
CLK Pulse Width to Return to Active Mode
q
50
ns
t
2
CONV
to CLK
Setup Time
q
80
ns
t
3
CONV
After Leading CLK
q
0
ns
t
4
CONV Pulse Width
(Note 11)
q
50
ns
t
5
Time from CLK
to Sample Mode
(Note 7)
80
ns
t
6
Aperture Delay of Sample-and-Hold
Jitter < 50ps (Note 7)
q
45
65
ns
t
7
Minimum Delay Between Conversion (Unipolar Mode)
q
265
385
ns
(Bipolar Mode V
SS
= 5V)
q
235
355
ns
t
8
Delay Time, CLK
to D
OUT
Valid
C
LOAD
= 20pF
q
40
80
ns
t
9
Delay Time, CLK
to D
OUT
Hi-Z
C
LOAD
= 20pF
q
40
80
ns
t
10
Time from Previous Data Remains Valid After CLK
C
LOAD
= 20pF
q
14
25
ns
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 GND.
Note 3: When these pin voltages are taken below V
SS
(ground for unipolar
mode) or above V
CC
, they will be clamped by internal diodes. This product
can handle input currents greater than 40mA below V
SS
(ground for
unipolar mode) or above V
CC
without latch-up.
Note 4: When these pin voltages are taken below V
SS
(ground for unipolar
mode), they will be clamped by internal diodes. This product can handle
input currents greater than 40mA below V
SS
(ground for unipolar mode)
without latch-up. These pins are not clamped to V
CC
.
Note 5: V
CC
= 5V, f
SAMPLE
= 400kHz, t
r
= t
f
= 5ns unless otherwise
specified.
Note 6: Recommended operating conditions.
Note 7: Guaranteed by design, not subject to test.
Note 8: Linearity, offset and full-scale specifications apply for unipolar and
bipolar modes.
Note 9: 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 10: Bipolar offset is the offset voltage measured from 0.5LSB when
the output code flickers between 0000 0000 0000 and 1111 1111 1111.
Note 11: The rising edge of CONV starts a conversion. If CONV returns
low at a bit decision point during the conversion, it can create small errors.
For best performance ensure that CONV returns low either within 120ns
after conversion starts (i.e., before the first bit decision) or after the 14
clock cycle. (Figure 13 Timing Diagram).
5
LTC1400
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
OUTPUT CODE
0
DIFFERENTIAL NONLINEARITY (LSBs)
4096
LTC1400 TPC01
1024
2048
3072
1.00
0.75
0.50
0.25
0
0.25
0.50
0.75
1.00
512
1536
2560
3584
f
SAMPLE
= 400kHz
Differential Nonlinearity vs
Output Code
Integral Nonlinearity vs
Output Code
OUTPUT CODE
0
INTEGRAL NONLINEARITY (LSBs)
4096
LTC1400 TPC02
1024
2048
3072
1.00
0.75
0.50
0.25
0
0.25
0.50
0.75
1.00
512
1536
2560
3584
f
SAMPLE
= 400kHz
INPUT FREQUENCY (kHz)
80
70
60
50
40
30
20
10
0
100
LTC1400 TPC06
10
1000
SIGNAL/(NOISE + DISTORTION) (dB)
V
IN
= 0dB
V
IN
= 20dB
V
IN
= 60dB
f
SAMPLE
= 400kHz
S/(N + D) vs Input Frequency
and Amplitude
Acquisition Time vs
Source Impedance
R
SOURCE
(
)
10
ACQUISITION TIME (ns)
4500
4000
3500
3000
2500
2000
1500
1000
500
0
100
1000
10000
LTC1400 TPC05
T
A
= 25
C
Signal-to-Noise Ratio (Without
Harmonics) vs Input Frequency
INPUT FREQUENCY (kHz)
80
70
60
50
40
30
20
10
0
100
LTC1400 TPC07
10
1000
SIGNAL-TO-NOISE RATIO (dB)
f
SAMPLE
= 400kHz
Peak Harmonic or Spurious Noise
vs Input Frequency
INPUT FREQUENCY (kHz)
10
SPURIOUS-FREE DYNAMIC RANGE (dB)
0
10
20
30
40
50
60
70
80
90
100
100
1000
LTC1400 TPC08
f
SAMPLE
= 400kHz
Reference Voltage vs
Load Current
LOAD CURRENT (mA)
8
REFERENCE VOLTAGE (V)
4
0
2
2.435
2,430
2.425
2.420
2.415
2.410
2.405
2.400
2.395
2.390
LTC1400 TPC03
6
2
5
1
1
7
3
TEMPERATURE (
C)
50
SUPPLY CURRENT (mA)
20
15
10
5
0
25
0
25
LTC1400 TPC04
50
75
100
125
f
SAMPLE
= 400kHz
Supply Current vs Temperature
RIPPLE FREQUENCY (kHz)
1
AMPLITUDE OF POWER SUPPLY FEEDTHROUGH (dB)
0
10
20
30
40
50
60
70
80
90
100
10
100
1M
LTC1400 TPC07.5
f
SAMPLE
= 400kHz
V
CC
(V
RIPPLE
= 1mV)
V
SS
(V
RIPPLE
= 10mV)
Power Supply Feedthrough vs
Ripple Frequency
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