FEATURES
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LTC2452
Ultra-Tiny, Differential, 16-Bit
ΔΣ
ADC with SPI Interface
DESCRIPTION
The LTC
®
2452 is an ultra-tiny, fully differential, 16-bit,
analog-to-digital converter. The LTC2452 uses a single
2.7V to 5.5V supply and communicates through an SPI
interface. The ADC is available in an 8-pin, 3mm × 2mm
DFN package or TSOT-23 package. It includes an integrated
oscillator that does not require any external components.
It uses a delta-sigma modulator as a converter core and
has no latency for multiplexed applications. The LTC2452
includes a proprietary input sampling scheme that reduces
the average input sampling current several orders of
magnitude when compared to conventional delta-sigma
converters. Additionally, due to its architecture, there is
negligible current leakage between the input pins.
The LTC2452 can sample at 60 conversions per second,
and due to the very large oversampling ratio, has extremely
relaxed antialiasing requirements. The LTC2452 includes
continuous internal offset and full-scale calibration algo-
rithms which are transparent to the user, ensuring accuracy
over time and over the operating temperature range. The
converter has an external REF pin and the differential input
voltage range can extend up to ±V
REF
.
Following a single conversion, the LTC2452 can automati-
cally enter a sleep mode and reduce its supply current to
less than 0.2μA. If the user reads the ADC once a second,
the LTC2452 consumes an average of less than 50μW
from a 2.7V supply.
Integral Nonlinearity, V
CC
= 3V
3
2.7V TO 5.5V
0.1μF
0.1μF
IN
+
REF
V
CC
INL (LSB)
CS
LTC2452
SCK
SDO
GND
–2
2452 TA01a
±V
CC
Differential Input Range
16-Bit Resolution (Including Sign), No Missing
Codes
2LSB Offset Error
4LSB Full-Scale Error
60 Conversions Per Second
Single Conversion Settling Time for Multiplexed
Applications
Single-Cycle Operation with Auto Shutdown
800μA Supply Current
0.2μA Sleep Current
Internal Oscillator—No External Components
Required
SPI Interface
Ultra-Tiny 3mm × 2mm DFN and TSOT-23 Packages
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.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 6208279, 6411242, 7088280, 7164378.
TYPICAL APPLICATION
2
1
10μF
T
A
= –45°C, 25°C, 90°C
0
–1
10k
10k
IN
–
3-WIRE SPI
INTERFACE
10k
R
0.1μF
–3
–3
1
2
–2
–1
0
DIFFERENTIAL INPUT VOLTAGE (V)
3
2452 TA01b
2452fb
1
LTC2452
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltage (V
CC
) ................................... –0.3V to 6V
Analog Input Voltage (V
IN+
, V
IN–
) .. –0.3V to (V
CC
+ 0.3V)
Reference Voltage (V
REF
) .............. –0.3V to (V
CC
+ 0.3V)
Digital Voltage (V
SDO
, V
SCK
, V
CS
) .. –0.3V to (V
CC
+ 0.3V)
Storage Temperature Range................... –65°C to 150°C
Operating Temperature Range
LTC2452C ................................................ 0°C to 70°C
LTC2452I.............................................. –40°C to 85°C
PIN CONFIGURATION
TOP VIEW
SCK
GND
REF
V
CC
1
2
3
4
9
8
7
6
5
SDO
CS
IN
+
IN
–
SCK 1
GND 2
REF 3
V
CC
4
TOP VIEW
8 SDO
7
CS
6 IN
+
5 IN
–
DD8 PACKAGE
8-LEAD (3mm 2mm) PLASTIC DFN
C/I GRADE T
JMAX
= 125°C,
θ
JA
= 76°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
TS8 PACKAGE
8-LEAD PLASTIC TSOT-23
C/I GRADE T
JMAX
= 125°C,
θ
JA
= 140°C/W
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
0°C to 70°C
–40°C to 85°C
LTC2452CDDB#TRMPBF
LTC2452CDDB#TRPBF
LDNJ
8-Lead Plastic (3mm × 2mm) DFN
LTC2452IDDB#TRMPBF
LTC2452IDDB#TRPBF
LDNJ
8-Lead Plastic (3mm × 2mm) DFN
LTC2452CTS8#TRMPBF
LTC2452CTS8#TRPBF
LTDPK
8-Lead Plastic TSOT-23
LTC2452ITS8#TRMPBF
LTC2452ITS8#TRPBF
LTDPK
8-Lead Plastic TSOT-23
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
Power Supply Rejection DC
l
ELECTRICAL CHARACTERISTICS
CONDITIONS
(Note 3)
(Note 4)
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MIN
16
TYP
1
2
0.02
0.01
0.02
2.2
80
MAX
10
10
0.02
UNITS
Bits
LSB
LSB
LSB/°C
% of FS
LSB/°C
μV
RMS
dB
2452fb
2
LTC2452
ANALOG INPUTS AND REFERENCES
SYMBOL
V
IN+
V
IN–
V
REF
V
OR+
, V
UR+
V
OR–
, V
UR–
C
IN
I
DC_LEAK(IN+)
I
DC_LEAK(IN–)
I
DC_LEAK(REF)
I
CONV
PARAMETER
Positive Input Voltage Range
Negative Input Voltage Range
Reference Voltage Range
Overrange/Underrange Voltage, IN
+
Overrange/Underrange Voltage, IN–
IN
+
, IN
–
Sampling Capacitance
IN
+
DC Leakage Current
IN
–
DC Leakage Current
REF DC Leakage Current
Input Sampling Current (Note 5)
V
IN
= GND (Note 10)
V
IN
= V
CC
(Note 10)
V
IN
= GND (Note 10)
V
IN
= V
CC
(Note 10)
V
REF
= 3V (Note 10)
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l
l
l
l
The
l
denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25°C.
CONDITIONS
l
l
l
MIN
0
0
2.5
TYP
MAX
V
CC
V
CC
V
CC
UNITS
V
V
V
LSB
LSB
pF
V
REF
= 5V, V
IN–
= 2.5V (See Figure 3)
V
REF
= 5V, V
IN+
= 2.5V (See Figure 3)
–10
–10
–10
–10
–10
8
8
0.35
1
1
1
1
1
50
10
10
10
10
10
nA
nA
nA
nA
nA
nA
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
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l
l
POWER REQUIREMENTS
MIN
2.7
TYP
MAX
5.5
UNITS
V
μA
μA
800
0.2
1200
0.6
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
CONDITIONS
DIGITAL INPUTS AND DIGITAL OUTPUTS
The
l
denotes the specifications which apply over the full
MIN
l
l
l
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
l
l
l
V
μA
2452fb
3
LTC2452
TIMING CHARACTERISTICS
The
l
denotes the specifications which apply over the full operating temperature
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
CS
Falling Edge to SCK Falling Edge
SCK Falling Edge to SDO Valid
(Note 7)
(Notes 7, 8)
(Notes 7, 8)
CONDITIONS
l
l
l
l
l
l
l
l
MIN
13
250
250
0
0
100
0
TYP
16.6
MAX
23
2
UNITS
ms
MHz
ns
ns
100
100
100
ns
ns
ns
ns
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.
V
REFCM
= V
REF
/2, FS = V
REF
V
IN
= V
IN+
– V
IN–
, –V
REF
≤ V
IN
≤ V
REF
; V
INCM
= (V
IN+
+ V
IN–
)/2.
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.
Guaranteed by design and test correlation.
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 4.
Note 8:
See Figure 5.
Note 9:
Input sampling current is the average input current drawn from the
input sampling network while the LTC2452 is actively sampling the input.
Note 10:
A positive current is flowing into the DUT pin.
TYPICAL PERFORMANCE CHARACTERISTICS
(T
A
= 25°C, unless otherwise noted)
Integral Nonlinearity, V
CC
= 5V
3
2
1
INL (LSB)
0
T
A
= –45°C, 25°C
–1
–2
–3
T
A
= 90°C
INL (LSB)
3
2
1
0
–1
–2
–3
–5 –4 –3 –2 –1 0 1 2 3 4
DIFFERENTIAL INPUT VOLTAGE (V)
5
Integral Nonlinearity, V
CC
= 3V
3
2
1
INL (LSB)
T
A
= –45°C, 25°C, 90°C
0
–1
–2
Maximum INL vs Temperature
V
CC
= V
REF
= 5V, 4.1V, 3V
–3
1
2
–2
–1
0
DIFFERENTIAL INPUT VOLTAGE (V)
3
2452 G02
–3
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G03
2452 G01
2452fb
4
LTC2452
TYPICAL PERFORMANCE CHARACTERISTICS
Offset Error vs Temperature
5
4
3
OFFSET ERROR (LSB)
GAIN ERROR (LSB)
2
1
0
–1
–2
–3
–4
–5
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G04
(T
A
= 25°C, unless otherwise noted)
Gain Error vs Temperature
5
4
3
2
1
0
–1
–2
–3
–4
–5
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G05
Transition Noise vs Temperature
10
9
TRANSITION NOISE RMS (μV)
8
7
6
5
4
3
2
1
0
–50
–25
V
CC
= 3V
V
CC
= 5V
V
CC
= V
REF
= 3V
V
CC
= V
REF
= 4.1V
V
CC
= V
REF
= 5V
V
CC
= V
REF
= 5V
V
CC
= V
REF
= 4.1V
V
CC
= V
REF
= 3V
25
50
0
TEMPERATURE (°C)
75
100
2452 G06
Conversion Mode Power Supply
Current vs Temperature
900
800
CONVERSION CURRENT (μA)
700
600
500
400
300
200
100
0
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G07
Sleep Mode Power Supply
Current vs Temperature
250
10000
AVERAGE POWER DISSIPATION (μW)
Average Power Dissipation
vs Temperature, V
CC
= 3V
V
CC
= 5V
V
CC
= 4.1V
V
CC
= 3V
SLEEP CURRENT (nA)
200
V
CC
= 5V
150
1000
25Hz OUTPUT SAMPLE RATE
10Hz OUTPUT SAMPLE RATE
100
1Hz OUTPUT SAMPLE RATE
10
100
V
CC
= 4.1V
50
V
CC
= 3V
0
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G08
0
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G09
Power Supply Rejection
vs Frequency at V
CC
0
–20
CONVERSION TIME (ms)
REJECTION (dB)
–40
–60
–80
21
20
19
18
17
16
15
Conversion Time vs Temperature
V
CC
= 5V, 4.1V, 3V
–100
–120
1
10
100 1k 10k 100k
FREQUENCY AT V
CC
(Hz)
1M
10M
14
–50
–25
25
50
0
TEMPERATURE (°C)
75
100
2452 G11
2452 G10
2452fb
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