LTC1400
Complete SO-8, 12-Bit,
400ksps ADC with Shutdown
FEATURES
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DESCRIPTION
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 30µW 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corp.
Complete 12-Bit ADC in SO-8
Single Supply 5V or
±
5V Operation
Sample Rate: 400ksps
Power Dissipation: 75mW (Typ)
72dB S/(N + D) and – 80dB THD at Nyquist
No Missing Codes over Temperature
Nap Mode with Instant Wake-Up: 6mW
Sleep Mode: 30µW
High Impedance Analog Input
Input Range (1mV/LSB): 0V to 4.096 or
±
2.048V
Internal Reference Can Be Overdriven Externally
3-Wire Interface to DSPs and Processors (SPI and
MICROWIRE
TM
Compatible)
APPLICATIONS
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High Speed Data Acquisition
Digital Signal Processing
Multiplexed Data Acquisition Systems
Audio and Telecom Processing
Digital Radio
Spectrum Analysis
Low Power and Battery-Operated Systems
Handheld or Portable Instruments
TYPICAL APPLICATION
Single 5V Supply, 400kHz, 12-Bit Sampling A/D Converter
5V
100
Power Consumption vs Sample Rate
+
10µF
ANALOG INPUT
(0V TO 4.096V)
2.42V REF
OUT
10µF
1
0.1µF
V
CC
LTC1400
V
SS
8
10
SUPPLY CURRENT (mA)
MPU
7
6
5
SERIAL
DATA LINK
LTC1400 • TA01
2
3
A
IN
V
REF
GND
1
SLEEP AND NAP MODE
BETWEEN CONVERSION
SLEEP MODE BETWEEN
CONVERSION
6.4MHz CLOCK
CONV
CLK
D
OUT
P1.4
P1.3
P1.2
+
0.1µF
0.1
4
0.01
0.001
0.01 0.1
U
U
U
NORMAL CONVERSION
NAP MODE
BETWEEN CONVERSION
1
10 100 1k 10k 100k 1M
SAMPLE RATE (Hz)
LTC1400 • TA02
1
LTC1400
ABSOLUTE
MAXIMUM
RATINGS
(Notes 1, 2)
PACKAGE/ORDER INFORMATION
TOP VIEW
V
CC
1
A
IN
2
V
REF
3
GND 4
8 V
SS
7 CONV
6 CLK
5 D
OUT
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
ORDER PART
NUMBER
LTC1400CS8
LTC1400IS8
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 130°C/ W
S8 PART MARKING
1400
1400I
Consult factory for PDIP packages and Military grade parts.
POWER REQUIRE E TS
SYMBOL
V
CC
V
SS
I
CC
PARAMETER
Positive Supply Voltage (Note 6)
Negative Supply Voltage (Note 6)
Positive Supply Current
(Note 5)
CONDITIONS
Unipolar
Bipolar
Bipolar Only
f
SAMPLE
= 400ksps
Nap Mode
Sleep Mode
f
SAMPLE
= 400ksps, V
SS
= – 5V
Nap Mode
Sleep Mode
f
SAMPLE
= 400ksps
Nap Mode
Sleep Mode
MIN
4.75
4.75
– 2.45
q
q
q
q
q
q
q
q
q
TYP
I
SS
Negative Supply Current
P
D
Power Dissipation
15
1.0
5.0
0.3
0.2
1
75
6
30
MAX
5.25
5.25
– 5.25
30
3.0
20.0
0.6
0.5
5
160
20
125
UNITS
V
V
V
mA
mA
µA
mA
mA
µA
mW
mW
µW
A ALOG I PUT
SYMBOL PARAMETER
V
IN
I
IN
C
IN
(Note 5)
CONDITIONS
4.75V
≤
V
CC
≤
5.25V (Unipolar)
4.75V
≤
V
CC
≤
5.25V, – 5.25V
≤
V
SS
≤
– 2.45V (Bipolar)
During Conversions (Hold Mode)
Between Conversions (Sample Mode)
During Conversions (Hold Mode)
q
q
q
MIN
TYP
0 to 4.096
±2.048
MAX
UNITS
V
V
Analog Input Range (Note 7)
Analog Input Leakage Current
Analog Input Capacitance
±1
45
5
2
U
W
U
U
UW
W W
W
U
U
µA
pF
pF
LTC1400
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
q
DY A IC ACCURACY
SYMBOL PARAMETER
S/(N + D) Signal-to-Noise
Plus Distortion Ratio
THD
Total Harmonic Distortion
Up to 5th Harmonic
Peak Harmonic or
Spurious Noise
IMD
Intermodulation Distortion
Full Power Bandwidth
I TER AL REFERE CE CHARACTERISTICS
PARAMETER
V
REF
Output Voltage
V
REF
Output Tempco
V
REF
Line Regulation
V
REF
Load Regulation
V
REF
Wake-Up Time from Sleep Mode (Note 7)
CONDITIONS
I
OUT
= 0
I
OUT
= 0
4.75V
≤
V
CC
≤
5.25V
– 5.25V
≤
V
SS
≤
0V
0
≤
I
OUT
≤
1mA
C
VREF
= 10µF
DIGITAL I PUTS AND OUTPUTS
SYMBOL PARAMETER
V
IH
V
IL
I
IN
C
IN
V
OH
V
OL
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
Low Level Output Voltage
U
U
U
W U
U
U
With internal reference (Notes 5, 8)
MIN
q
CONDITIONS
(Note 9)
(Note 10)
q
q
q
TYP
MAX
±1
±1
±6
±8
±15
UNITS
Bits
LSB
LSB
LSB
LSB
LSB
ppm/°C
12
±10
±45
V
CC
= 5V, V
SS
= – 5V, f
SAMPLE
= 400kHz
CONDITIONS
100kHz Input Signal
200kHz Input Signal
100kHz Input Signal
200kHz Input Signal
100kHz Input Signal
200kHz Input Signal
f
IN1
= 99.51kHz, f
IN2
= 102.44kHz
f
IN1
= 199.12kHz, f
IN2
= 202.05kHz
q
q
MIN
Commercial
Industrial
q
q
TYP
72
72
– 82
– 80
– 84
– 82
– 82
– 70
4
900
MAX
UNITS
dB
dB
dB
70
69
– 76
– 76
dB
dB
dB
dB
dB
dB
MHz
kHz
Full Linear Bandwidth (S/(N + D)
≥
68dB)
U
(Note 5)
MIN
2.400
q
TYP
2.420
±10
0.01
0.01
2
4
MAX
2.440
±45
UNITS
V
ppm/°C
LSB/ V
LSB/ V
LSB/mA
ms
(Note 5)
MIN
q
q
q
CONDITIONS
V
CC
= 5.25V
V
CC
= 4.75V
V
IN
= 0V to V
CC
V
CC
= 4.75V, I
O
= – 10µA
V
CC
= 4.75V, I
O
= – 200µA
V
CC
= 4.75V, I
O
= 160µA
V
CC
= 4.75V, I
O
= 1.6mA
TYP
MAX
0.8
±10
UNITS
V
V
µA
pF
V
V
2.0
5
4.7
q
q
4.0
0.05
0.10
0.4
V
V
3
LTC1400
DIGITAL I PUTS AND OUTPUTS
SYMBOL PARAMETER
I
OZ
C
OZ
I
SOURCE
I
SINK
Hi-Z Output Leakage D
OUT
Hi-Z Output Capacitance D
OUT
(Note 7)
Output Source Current
Output Sink Current
TI I G CHARACTERISTICS
SYMBOL
f
SAMPLE(MAX)
t
CONV
t
ACQ
f
CLK
t
CLK
t
WK(NAP)
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 (Unipolar Mode)
(Bipolar Mode V
SS
= – 5V)
CLK Frequency
CLK Pulse Width
Time to Wake Up from Nap Mode
CLK Pulse Width to Return to Active Mode
CONV↑ to CLK↑ Setup Time
CONV↑ After Leading CLK↑
CONV Pulse Width
Time from CLK↑ to Sample Mode
Aperture Delay of Sample-and-Hold
Minimum Delay Between Conversion (Unipolar Mode)
(Bipolar Mode V
SS
= – 5V)
Delay Time, CLK↑ to D
OUT
Valid
Delay Time, CLK↑ to D
OUT
Hi-Z
Time from Previous Data Remains Valid After CLK↑
C
LOAD
= 20pF
C
LOAD
= 20pF
C
LOAD
= 20pF
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.
4
U
U
(Note 5)
MIN
q
CONDITIONS
V
OUT
= 0V to V
CC
V
OUT
= 0
V
OUT
= V
CC
TYP
15
– 10
10
MAX
±10
UNITS
µA
pF
mA
mA
UW
(Note 5)
CONDITIONS
(Note 6)
f
CLK
= 6.4MHz
(Note 7)
q
q
q
q
q
MIN
400
TYP
MAX
2.1
UNITS
kHz
µs
ns
ns
MHz
ns
ns
ns
ns
ns
ns
230
200
0.1
50
350
50
80
0
50
80
45
265
235
40
40
14
25
300
270
6.4
(Note 7)
(Note 7)
q
q
q
q
(Note 11)
(Note 7)
Jitter < 50ps (Note 7)
q
ns
65
385
355
80
80
ns
ns
ns
ns
ns
ns
q
q
q
q
q
q
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).
LTC1400
TYPICAL PERFORMANCE CHARACTERISTICS
Differential Nonlinearity vs
Output Code
1.00
1.00
f
SAMPLE
= 400kHz
INTEGRAL NONLINEARITY (LSBs)
DIFFERENTIAL NONLINEARITY (LSBs)
0.50
0.25
0
–0.25
–0.50
–0.75
–1.00
0
512 1024 1536 2048 2560 3072 3584 4096
OUTPUT CODE
LTC1400 • TPC01
0.50
0.25
0
–0.25
–0.50
–0.75
–1.00
0
512 1024 1536 2048 2560 3072 3584 4096
OUTPUT CODE
LTC1400 • TPC02
SIGNAL/(NOISE + DISTORTION) (dB)
0.75
Signal-to-Noise Ratio (Without
Harmonics) vs Input Frequency
80
SPURIOUS-FREE DYNAMIC RANGE (dB)
70
SIGNAL-TO-NOISE RATIO (dB)
–30
–40
–50
–60
–70
–80
–90
–100
10
100
INPUT FREQUENCY (kHz)
1000
LTC1400 • TPC08
ACQUISITION TIME (ns)
60
50
40
30
20
10
f
SAMPLE
= 400kHz
0
10
100
INPUT FREQUENCY (kHz)
1000
LTC1400 • TPC07
AMPLITUDE OF POWER SUPPLY FEEDTHROUGH (dB)
Reference Voltage vs
Load Current
2.435
2,430
REFERENCE VOLTAGE (V)
2.420
2.415
2.410
2.405
2.400
2.395
2.390
–8 –7 –6 –5 –4 –3 –2 –1
LOAD CURRENT (mA)
0
1
2
–30
–40
–50
–60
–70
–80
–90
–100
1
10
100
RIPPLE FREQUENCY (kHz)
1M
V
CC
(V
RIPPLE
= 1mV)
V
SS
(V
RIPPLE
= 10mV)
SUPPLY CURRENT (mA)
2.425
U W
Integral Nonlinearity vs
Output Code
80
S/(N + D) vs Input Frequency
and Amplitude
V
IN
= 0dB
70
60
50
40
30
20
10
f
SAMPLE
= 400kHz
0
10
100
INPUT FREQUENCY (kHz)
1000
LTC1400 • TPC06
f
SAMPLE
= 400kHz
0.75
V
IN
= –20dB
V
IN
= – 60dB
Peak Harmonic or Spurious Noise
vs Input Frequency
0
–10
–20
f
SAMPLE
= 400kHz
4500
4000
3500
3000
2500
2000
1500
1000
500
0
Acquisition Time vs
Source Impedance
T
A
= 25°C
10
100
1000
R
SOURCE
(Ω)
10000
LTC1400 • TPC05
Power Supply Feedthrough vs
Ripple Frequency
0
–10
–20
20
f
SAMPLE
= 400kHz
15
Supply Current vs Temperature
f
SAMPLE
= 400kHz
10
5
0
–50 –25
50
75
0
25
TEMPERATURE (°C)
100
125
LTC1400 • TPC03
LTC1400 • TPC07.5
LTC1400 • TPC04
5
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