converters with an integrated precision reference and
a selectable 250sps or 1ksps output rate. They use a
single 2.7V to 5.5V supply and communicate through a
SPI Interface. The LTC2470 is single-ended with a 0V to
V
REF
input range and the LTC2472 is differential with a
±V
REF
input range. Both ADC’s include a 1.25V integrated
reference with 2ppm/°C drift performance and 0.1% initial
accuracy. The converters are available in a 12-pin DFN
3mm × 3mm package or an MSOP-12 package. They
include an integrated oscillator and perform conver-
sions with no latency for multiplexed applications. The
LTC2470/LTC2472 include a proprietary input sampling
scheme that reduces the average input current several
orders of magnitude when compared to conventional
delta sigma converters.
Following a single conversion, the LTC2470/LTC2472
automatically power down the converter and can also be
configured to power down the reference. When both the
ADC and reference are powered down, the supply current
is reduced to 200nA.
The LTC2470/LTC2472 include a user selectable 250sps
or 1ksps output rate and due to a large oversampling
ratio (8,192 at 250sps and 2,048 at 1ksps) have relaxed
anti-aliasing requirements.
16-Bit Resolution, No Missing Codes
Internal, High Accuracy Reference—10ppm/°C (Max)
Single-Ended (LTC2470) or Differential (LTC2472)
Selectable 250sps/1ksps Output Rate
1mV Offset Error
0.01% Gain Error
Single Conversion Settling Time for Multiplexed
Applications
Single-Cycle Operation with Auto Shutdown
3.5mA (Typ) Supply Current
2μA (Max) Sleep Current
Internal Oscillator—No External Components
Required
SPI Interface
Small 12-Lead, 3mm × 3mm DFN and MSOP
Packages
APPLICATIONS
n
n
n
n
n
n
n
System Monitoring
Environmental Monitoring
Direct Temperature Measurements
Instrumentation
Industrial Process Control
Data Acquisition
Embedded ADC Upgrades
L,
LT, LTC, LTM, Linear Technology and the Linear logo 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
2.7V TO 5.5V
REFERENCE OUTPUT VOLTAGE (V)
1.2520
1.2515
1.2510
1.2505
1.2500
1.2495
1.2490
1.2485
1.2480
–50
0.1μF
0.1μF
IN
+
LTC2472
IN
–
10k
0.1μF
R
REF
–
REFOUT
0.1μF
COMP V
CC
SCK
SDO
CS
GND
24702 TA01a
V
REF
vs Temperature
0.1μF
10μF
10k
10k
SPI
INTERFACE
–30
–10 10
30
50
TEMPERATURE (°C)
70
90
24702 TA01b
24702f
1
LTC2470/LTC2472
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltage (V
CC
) ................................... –0.3V to 6V
Analog Input Voltage
(V
IN+
, V
IN –
, V
IN
, V
REF –
,
V
COMP
, V
REFOUT
) ...........................–0.3V to (V
CC
+ 0.3V)
Digital Voltage
(V
SDI
, V
SDO
, V
SCK
, V
CS
) ................–0.3V to (V
CC
+ 0.3V)
Storage Temperature Range .................. –65°C to 150°C
Operating Temperature Range
LTC2470C/LTC2472C ............................... 0°C to 70°C
LTC2470I/LTC2472I .............................–40°C to 85°C
PIN CONFIGURATION
LTC2472
TOP VIEW
TOP VIEW
REFOUT
COMP
CS
SDI
SCK
SDO
1
2
3
4
5
6
13
GND
12 V
CC
11 GND
10 IN
–
9 IN
+
8 REF
–
7 GND
REFOUT
COMP
CS
SDI
SCK
SDO
1
2
3
4
5
6
12
11
10
9
8
7
V
CC
GND
IN
–
IN
+
REF
–
GND
LTC2472
DD PACKAGE
12-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 13) PCB GROUND CONNECTION OPTIONAL
LTC2470
TOP VIEW
LTC2470
MS PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
TOP VIEW
REFOUT
COMP
CS
SDI
SCK
SDO
1
2
3
4
5
6
13
GND
12 V
CC
11 GND
10 GND
9 IN
8 REF
–
7 GND
REFOUT
COMP
CS
SDI
SCK
SDO
1
2
3
4
5
6
12
11
10
9
8
7
V
CC
GND
GND
IN
REF
–
GND
DD PACKAGE
12-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 13) PCB GROUND CONNECTION OPTIONAL
MS PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2470CDD#PBF
LTC2470IDD#PBF
LTC2470CMS#PBF
LTC2470IMS#PBF
LTC2472CDD#PBF
LTC2472IDD#PBF
LTC2472CMS#PBF
LTC2472IMS#PBF
TAPE AND REEL
LTC2470CDD#TRPBF
LTC2470IDD#TRPBF
LTC2470CMS#TRPBF
LTC2470IMS#TRPBF
LTC2472CDD#TRPBF
LTC2472IDD#TRPBF
LTC2472CMS#TRPBF
LTC2472IMS#TRPBF
PART MARKING*
LFPV
LFPV
2470
2470
LFGV
LFGV
2472
2472
PACKAGE DESCRIPTION
12-Lead Plastic (3mm × 3mm) DFN
12-Lead Plastic (3mm × 3mm) DFN
12-Lead Plastic MSOP-12
12-Lead Plastic MSOP-12
12-Lead Plastic (3mm × 3mm) DFN
12-Lead Plastic (3mm × 3mm) DFN
12-Lead Plastic MSOP-12
12-Lead Plastic MSOP-12
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard 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/
24702f
2
LTC2470/LTC2472
ELECTRICAL CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Nonlinearity
Offset Error
Offset Error Drift
Gain Error
Gain Error Drift
Transition Noise
Power Supply Rejection DC
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 2)
CONDITIONS
(Note 3)
Output Rate 250sps (Note 4)
Output Rate 1000sps (Note 4)
l
l
l
l
MIN
16
TYP
2
8
±1
0.05
±0.01
0.15
3
80
MAX
8.5
12
±2.5
±0.25
UNITS
Bits
LSB
LSB
mV
LSB/°C
% of FS
LSB/°C
μV
RMS
dB
ANALOG INPUTS
specifications are at T
A
= 25°C.
PARAMETER
SYMBOL
V
IN+
V
IN–
V
IN
V
OR+
, V
UR+
V
OR–
, V
UR–
C
IN
The
l
denotes the specifications which apply over the full operating temperature range, otherwise
CONDITIONS
LTC2472
LTC2472
LTC2470
V
IN–
= 0.625V
V
IN+
= 0.625V
V
IN
= GND (Note 5)
V
IN
= V
CC
(Note 5)
l
l
l
l
l
l
MIN
0
0
0
TYP
MAX
V
REF
V
REF
V
REF
UNITS
V
V
V
LSB
LSB
pF
Positive Input Voltage Range
Negative Input Voltage Range
Input Voltage Range
Overrange/Underrange Voltage, IN
+
Overrange/Underrange Voltage, IN–
IN
+
, IN
–
, IN Sampling Capacitance
8
8
0.35
–10
–10
1.247
±1
±1
50
1.25
±2
±5
–90
l
l
I
DC_LEAK(IN+, IN–, IN)
IN
+
, IN
–
DC Leakage Current (LTC2472)
IN DC Leakage Current (LTC2470)
I
CONV
V
REF
Input Sampling Current (Note 8)
Reference Output Voltage
Reference Voltage Coefficient
10
10
1.253
±10
nA
nA
nA
V
ppm/°C
ppm/°C
dB
mA
μA
mV/mA
nV/√Hz
(Note 9)
C-Grade
I-Grade
2.7V ≤ V
CC
≤ 5.5V
V
CC
= 5.5, Forcing Output to GND
V
CC
= 5.5, Forcing Output to GND
2.7V ≤ V
CC
≤ 5.5V, I
OUT
= 100μA Sourcing
,
,
C
COMP
= 0.1μF C
REFOUT
= 0.1μF At f =
1ksps
l
Reference Line Regulation
Reference Short Circuit Current
COMP Pin Short Circuit Current
Reference Load Regulation
Reference Output Noise Density
35
200
3.5
30
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
Conversion
Nap
Sleep
CS
= GND (Note 6) LTC2472
CS
= GND (Note 6) LTC2470
CS
= V
CC
(Note 6)
CS
= V
CC
(Note 6)
CONDITIONS
l
l
l
l
l
POWER REQUIREMENTS
MIN
2.7
TYP
MAX
5.5
UNITS
V
mA
mA
μA
μA
3.5
2.5
800
0.2
5
4
1500
2
24702f
3
LTC2470/LTC2472
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
The
l
denotes the specifications which apply over the full
CONDITIONS
l
l
l
MIN
V
CC
– 0.3
TYP
MAX
0.3
UNITS
V
V
μA
pF
V
–10
10
V
CC
– 0.5
10
0.4
–10
10
V
μA
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
CONV1
t
CONV2
f
SCK
t
lSCK
t
hSCK
t
1
t
2
t
3
t
4
t
5
t
KQ
PARAMETER
Conversion Time
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
SDI Setup Before SCK↑
SDI Hold After SCK↑
SCK Falling Edge to SDO Valid
(Note 7)
(Note 7)
(Note 7)
(Note 7)
(Note 7)
(Notes 3, 7)
(Notes 3, 7)
(Note 7)
CONDITIONS
SPD = 0
SPD = 1
l
l
l
l
l
l
l
l
l
l
l
MIN
3.2
0.8
250
250
0
0
100
100
100
0
TYP
4
1
MAX
4.8
1.2
2
UNITS
ms
ms
MHz
ns
ns
100
100
ns
ns
ns
ns
ns
100
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
REF
≤ V
IN
≤ V
REF
V
IN
= V
IN+
– V
IN –
, V
INCM
= (V
IN+
+ V
IN –
)/2. (LTC2472)
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.
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 5.
Note 8:
Input sampling current is the average input current drawn from
the input sampling network while the LTC2470/LTC2472 is actively
sampling the input.
Note 9:
Temperature coefficient is calculated by dividing the maximum
change in output voltage by the specified temperature range.
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