FEATURES
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LTC2450-1
Easy-to-Use, Ultra-Tiny
16-Bit
ΔΣ
ADC
DESCRIPTION
The LTC
®
2450-1 is a low power, ultra-tiny 16-bit analog-
to-digital converter designed for space constrained ap-
plications requiring 16-bit performance. The LTC2450-1
uses a single 2.7V to 5.5V supply, accepts a single-ended
analog input voltage, and communicates through an SPI
interface. It includes an integrated oscillator that does
not require any external components. The delta-sigma
modulator converter core provides single-cycle settling
time for multiplexed applications. The converter is avail-
able in a 6-pin, 2mm
×
2mm DFN package. The LTC2450-1
implements a proprietary input sampling scheme that
reduces the average input sampling current several orders
of magnitude.
The LTC2450-1 is capable of up to 60 conversions per
second and, due to the very large oversampling ratio, has
extremely relaxed antialiasing requirements. The converter
uses its power supply voltage as the reference voltage and
the single-ended, rail-to-rail input voltage range extends
from GND to V
CC
.
Following a conversion, the LTC2450-1 can automatically
enter a sleep mode and reduce its power to less than
500nA. At an output rate of 1Hz, the LTC2450-1 consumes
an average of less than 25μW from a 2.7V supply.
GND to V
CC
Single-Ended Input Range
60 Conversions Per Second
0.02LSB RMS Noise
16-Bits, No Missing Codes
0.5mV Offset Error
4LSB Full-Scale Error
Single Conversion Settling Time for Multiplexed
Applications
Single Cycle Operation with Auto Shutdown
350μA Supply Current
50nA Sleep Current
Internal Oscillator—No External Components
Required
Single Supply, 2.7V to 5.5V Operation
SPI Interface
Ultra-Tiny, 2mm
×
2mm DFN Package
APPLICATIONS
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System Monitoring
Environmental Monitoring
Direct Temperature Measurements
Instrumentation
Industrial Process Control
Data Acquisition
Embedded ADC Upgrades
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Easy Drive
is a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 6208279, 6411242, 7088280, 7164378.
TYPICAL APPLICATION
3.0
2.5
2.7 TO 5.5V
0.1μF
10μF
INL (LSB)
2.0
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
0
Integral Nonlinearity
V
CC
= V
REF
= 3V
1k
SENSE
CLOSE TO
CHIP
V
IN
0.1μF
V
CC
LTC2450-1
GND
CS
SCK
SDO
24501 TA01
T
A
= –45°C, 25°C, 90°C
3-WIRE SPI
INTERFACE
0.5
1.0
1.5
2.0
INPUT VOLTAGE (V)
2.5
3.0
24501 G02
24501fb
1
LTC2450-1
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
V
CC
1
V
IN
2
GND 3
7
6 SCK
5 SDO
4
CS
Supply Voltage (V
CC
) ................................... –0.3V to 6V
Analog Input Voltage (V
IN
) ............–0.3V to (V
CC
+ 0.3V)
Digital Input Voltage......................–0.3V to (V
CC
+ 0.3V)
Digital Output Voltage ...................–0.3V to (V
CC
+ 0.3V)
Operating Temperature Range
LTC2450C-1 ............................................. 0°C to 70°C
LTC2450I-1 .......................................... –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
DC PACKAGE
6-LEAD (2mm × 2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 102°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI)
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
LTC2450CDC-1#TRMPBF
LTC2450CDC-1#TRPBF
LCTR
6-Lead (2mm × 2mm) Plastic DFN
LTC2450IDC-1#TRMPBF
LTC2450IDC-1#TRPBF
LCTR
6-Lead (2mm × 2mm) Plastic DFN
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
PARAMETER
Resolution (No missing codes)
Integral Nonlinearity
Offset Error
Offset Error Drift
Gain Error
Gain Error Drift
Transition Noise
l
ELECTRICAL CHARACTERISTICS
(Note 3)
(Note 4)
CONDITIONS
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l
l
MIN
16
TYP
2
0.5
0.02
0.01
0.02
1.4
MAX
10
2
0.02
UNITS
Bits
LSB
mV
LSB/°C
% of FS
LSB/°C
μV
RMS
ANALOG INPUT
The
l
denotes the specifications which apply over the full operating temperature range,otherwise
specifications are at T
A
= 25°C.
SYMBOL
V
IN
C
IN
I
DC_LEAK
(V
IN
)
I
CONV
PARAMETER
Input Voltage Range
IN Sampling Capacitance
IN DC Leakage Current
Input Sampling Current (Note 9)
V
IN
= GND (Note 5)
V
IN
= V
CC
(Note 5)
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l
CONDITIONS
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MIN
0
TYP
0.35
MAX
V
CC
UNITS
pF
–10
–10
1
1
50
10
10
nA
nA
nA
24501fb
2
LTC2450-1
POWER REQUIREMENTS
The
l
denotes the specifications which apply over the full operating temperature
range,otherwise specifications are at T
A
= 25°C.
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
Conversion
Sleep
CS
= GND (Note 6)
CS
= V
CC
(Note 6)
CONDITIONS
l
l
l
MIN
2.7
TYP
MAX
5.5
UNITS
V
μA
μA
350
0.05
600
0.5
The
l
denotes the specifications which apply over the full
operating temperature range,otherwise specifications are at T
A
= 25°C. (Note 2)
SYMBOL
V
IH
V
IL
I
IN
C
IN
V
OH
V
OL
I
OZ
PARAMETER
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Digital Input Capacitance
High Level Output Voltage
Low Level Output Voltage
Hi-Z Output Leakage Current
I
O
= –800μA
I
O
= –1.6mA
l
l
l
DIGITAL INPUTS AND DIGITAL OUTPUTS
CONDITIONS
MIN
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l
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TYP
MAX
0.3
UNITS
V
V
μA
pF
V
V
CC
– 0.3
–10
10
V
CC
– 0.5
0.4
–10
10
10
V
μA
range,otherwise specifications are at T
A
= 25°C.
SYMBOL
t
CONV
f
SCK
t
lSCK
t
hSCK
t
1
t
2
t
3
t
KQ
PARAMETER
Conversion Time
SCK Frequency Range
SCK Low Period
SCK High Period
CS
Falling Edge to SDO Low Z
CS
Rising Edge to SDO High Z
TIMING CHARACTERISTICS
The
l
denotes the specifications which apply over the full operating temperature
CONDITIONS
l
l
l
l
l
l
l
l
MIN
14
250
250
0
0
100
0
TYP
16.6
MAX
21
2
UNITS
ms
MHz
ns
ns
(Notes 7, 8)
(Notes 7, 8)
(Note 7)
100
100
100
ns
ns
ns
ns
CS
Falling Edge to SCK Falling Edge
SCK Falling Edge to SDO Valid
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All voltage values are with respect to GND. V
CC
= 2.7V to 5.5V
unless otherwise specified.
Note 3:
Guaranteed by design, not subject to test.
Note 4:
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. Guaranteed by design, test correlation and 3 point transfer curve
measurement.
Note 5:
CS
= V
CC
. A positive current is flowing into the DUT pin.
Note 6:
SCK = V
CC
or GND. SDO is high impedance.
Note 7:
See Figure 3.
Note 8:
See Figure 4.
Note 9:
Input sampling current is the average input current drawn from
the input sampling network while the LTC2450-1 is actively sampling the
input.
24501fb
3
LTC2450-1
TYPICAL PERFORMANCE CHARACTERISTICS
Integral Nonlinearity
3.0
2.5
2.0
1.5
1.0
INL (LSB)
INL (LSB)
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
INPUT VOLTAGE (V)
24501 G01
Integral Nonlinearity
3.0
2.5
2.0
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
0
0.5
1.0
1.5
2.0
INPUT VOLTAGE (V)
2.5
3.0
T
A
= –45°C, 25°C, 90°C
INL (LSB)
5.0
V
CC
= V
REF
= 3V
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
Maximum INL vs Temperature
V
CC
= V
REF
= 5V
V
CC
= 5V
V
CC
= 4.1V
V
CC
= 3V
T
A
= –45°C, 25°C, 90°C
0
–50
–25
50
25
0
TEMPERATURE (°C)
75
100
24501 G03
24501 G02
Offset Error vs Temperature
7
V
CC
= 4.1V
6
GAIN ERROR (LSB)
5
OFFSET (LSB)
4
3
2
1
0
–50
V
CC
= 5.5V
V
CC
= 2.7V
5
4
3
Gain Error vs Temperature
3.00
2.75
TRANSITION NOISE RMS (μV)
2.50
2.25
2.00
1.75
Transition Noise vs Temperature
V
CC
= 2.7V
2
1
0
V
CC
= 4.1V
–1
–50
V
CC
= 5.5V
1.50 V
CC
= 4.1V
1.25
1.00
0.50
0.75
0.25
0
–50 –30
V
CC
= 3V
V
CC
= 5V
–25
50
25
0
TEMPERATURE (°C)
75
100
24501 G04
–25
0
25
50
TEMPERATURE (°C)
75
100
50
–10 10 30
TEMPERATURE (°C)
70
90
24501 G06
24501 G05
Transition Noise vs Output Code
3.00
2.75
TRANSITION NOISE RMS (μV)
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.50
0.75
0.25
0
0.80
1.00
0.40
0.60
0
0.20
OUTPUT CODE (NORMALIZED TO FULL SCALE)
24501 G07
Conversion Mode Power Supply
Current vs Temperature
500
V
CC
= 5V
V
CC
= 3V
300
V
CC
= 4.1V
T
A
= 25°C
CONVERSION CURRENT (μA)
400
V
CC
= 5V
V
CC
= 3V
200
100
0
–45
–25
35
15
–5
55
TEMPERATURE (°C)
75
95
24501 G08
24501fb
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LTC2450-1
TYPICAL PERFORMANCE CHARACTERISTICS
Sleep Mode Power Supply
Current vs Temperature
250
10000
AVERAGE SUPPLY POWER (μW)
Average Supply Power
vs Temperature, V
CC
= 3V
SLEEP MODE CURRENT (nA)
200
V
CC
= 5V
150
V
CC
= 4.1V
60 Hz OUTPUT SAMPLE RATE
1000
10 Hz OUTPUT SAMPLE RATE
100
100
1 Hz OUTPUT SAMPLE RATE
50
V
CC
= 3V
0
–45
–25
35
15
–5
55
TEMPERATURE (°C)
75
95
10
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
24501 G10
24501 G09
Conversion Period vs
Temperature
22
21
CONVERSION TIME (ms)
20
V
CC
= 5.5V, 4.1V, 2.7V
19
18
17
16
15
–45 –25
35
15
55
–5
TEMPERATURE (°C)
75
95
24501 G11
24501fb
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