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 an
I
2
C Interface. The LTC2471 is single-ended with a 0V to
V
REF
input range and the LTC2473 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
LTC2471/LTC2473 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 LTC2471/LTC2473
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 LTC2471/LTC2473 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 (LTC2471) or Differential (LTC2473)
Selectable 250sps/1ksps Output Rate
1mV Offset Error
0.01% Gain Error
Single Conversion Settling Time Simplifies
Multiplexed Applications
Single-Cycle Operation with Auto Shutdown
3.5mA (Typ) Supply Current
2μA (Max) Sleep Current
Internal Oscillator—No External Components
Required
I
2
C 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
+
LTC2473
IN
–
10k
0.1μF
R
REF
–
AO
GND
24713 TA01a
V
REF
vs Temperature
0.1μF
REFOUT
COMP V
CC
SCL
SDA
0.1μF
10μF
10k
10k
I
2
C
INTERFACE
–30
–10 10
30
50
TEMPERATURE (°C)
70
90
24713 TA01b
24713f
1
LTC2471/LTC2473
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
SDA
, V
SCL
, V
AO
)..........................–0.3V to (V
CC
+ 0.3V)
Storage Temperature Range .................. –65°C to 150°C
Operating Temperature Range
LTC2471C/LTC2473C ............................... 0°C to 70°C
LTC2471I/LTC2473I..............................–40°C to 85°C
PIN CONFIGURATION
LTC2473
TOP VIEW
REFOUT
COMP
AO
GND
SCL
SDA
1
2
3
4
5
6
13
GND
12 V
CC
11 GND
10 IN
–
9 IN
+
8 REF
–
7 GND
REFOUT
COMP
AO
GND
SCL
SDA
1
2
3
4
5
6
TOP VIEW
12
11
10
9
8
7
V
CC
GND
IN
–
IN
+
REF
–
GND
LTC2473
DD PACKAGE
12-LEAD (3mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 13) PCB GROUND CONNECTION
LTC2471
TOP VIEW
REFOUT
COMP
AO
GND
SCL
SDA
1
2
3
4
5
6
13
GND
12 V
CC
11 GND
10 GND
9 IN
8 REF
–
7 GND
LTC2471
MS PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
TOP VIEW
REFOUT
COMP
AO
GND
SCL
SDA
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
MS PACKAGE
12-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 130°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2471CDD#PBF
LTC2471IDD#PBF
LTC2471CMS#PBF
LTC2471IMS#PBF
LTC2473CDD#PBF
LTC2473IDD#PBF
LTC2473CMS#PBF
LTC2473IMS#PBF
TAPE AND REEL
LTC2471CDD#TRPBF
LTC2471IDD#TRPBF
LTC2471CMS#TRPBF
LTC2471IMS#TRPBF
LTC2473CDD#TRPBF
LTC2473IDD#TRPBF
LTC2473CMS#TRPBF
LTC2473IMS#TRPBF
PART MARKING*
LFPW
LFPW
2471
2471
LFPX
LFPX
2473
2473
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/
24713f
2
LTC2471/LTC2473
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
LTC2473
LTC2473
LTC2471
V
IN–
= 0.625V
V
IN+
= 0.625V
V
IN
= GND (Note 8)
V
IN
= V
CC
(Note 8)
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 (LTC2473)
IN DC Leakage Current (LTC2471)
I
CONV
V
REF
Input Sampling Current (Notes 5, 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 (Note 8)
V
CC
= 5.5, Forcing Output to GND (Note 8)
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
LTC2473 (Note 8)
LTC2471 (Note 8)
(Note 8)
(Note 8)
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
24713f
3
LTC2471/LTC2473
I
2
C INPUTS AND OUTPUTS
SYMBOL
V
IH
V
IL
I
I
V
HYS
V
OL
I
IN
C
I
C
B
V
IH(A0)
V
IL(A0)
PARAMETER
High Level Input Voltage
Low Level Input Voltage
Digital Input Current
Hysteresis of Schmidt Trigger Inputs
Low Level Output Voltage (SDA)
Input Leakage
Capacitance for Each I/O Pin
Capacitance Load for Each Bus Line
High Level Input Voltage for Address Pin
Low Level Input Voltage for Address Pin
(Note 8)
(Note 3)
I = 3mA
0.1V
CC
≤ V
IN
≤ 0.9V
CC
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Notes 2, 7)
CONDITIONS
l
l
l
l
l
l
l
l
l
l
MIN
0.7V
CC
TYP
MAX
0.3V
CC
UNITS
V
V
μA
V
V
μA
pF
pF
V
V
–10
0.05V
CC
10
0.4
1
10
400
0.95V
CC
0.05V
CC
I
2
C TIMING CHARACTERISTICS
SYMBOL
t
CONV1
t
CONV2
f
SCL
t
HD(SDA,STA)
t
LOW
t
HIGH
t
SU(STA)
t
HD(DAT)
t
SU(DAT)
t
r
t
f
t
SU(STO)
t
BUF
t
OF
t
SP
PARAMETER
Conversion Time
Conversion Time
SCL Clock Frequency
Hold Time (Repeated) START Condition
LOW Period of the SCL Pin
HIGH Period of the SCL Pin
Set-Up Time for a Repeated START
Condition
Data Hold Time
Data Set-Up Time
Rise Time for SDA, SCL Signals
Fall Time for SDA, SCL Signals
Set-Up Time for STOP Condition
Bus Free Time Between a Stop and Start
Condition
Output Fall Time V
IHMIN
to V
ILMAX
Input Spike Suppression
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 2, 7)
CONDITIONS
SPD = 0
SPD = 1
l
l
l
l
l
l
l
l
l
l
l
l
l
MIN
3.2
0.8
0
0.6
1.3
0.6
0.6
0
100
20 + 0.1C
B
20 + 0.1C
B
0.6
1.3
20 + 0.1C
B
TYP
4
1
MAX
4.8
1.2
400
UNITS
ms
ms
kHz
μs
μs
μs
μs
0.9
300
300
μs
ns
ns
ns
μs
μs
(Note 6)
(Note 6)
Bus Load C
B
= 10pF to 400pF (Note 6)
l
l
250
50
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
REF
≤ V
IN
≤ V
REF
V
IN
= V
IN+
– V
IN –
, V
INCM
= (V
IN+
+ V
IN –
)/2. (LTC2473)
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:
Input sampling current is the average input current drawn from
the input sampling network while the LTC2471/LTC2473 are converting.
Note 6:
C
B
= capacitance of one bus line in pF.
Note 7:
All values refer to V
IH(MIN
) and V
IL(MAX)
levels.
Note 8:
A positive current is flowing into the DUT pin.
Note 9:
Voltage temperature coefficient is calculated by dividing the
maximum change in output voltage by the specified temperature range.
1. Introduction
Electronic scales are gradually replacing traditional measuring tools like springs and balances in everyday life, such as electronic price computing scales and electronic weigh...[详细]
C++ 属于面向对象的编程语言，OOP的思想不必多说，特别对于复杂的软件工程来说，利用OOP绝对是事半功倍，相对于传统的C来说； 当然用C来写单片机程序无可厚非，已经延续了一个传统，从大学时学的开始到工作岗位，好多人都是一直用C来做，但是既然Keil支持C++编译， 可以用C++来编写你的代码，可以利用高级语言来结构化，清晰化你的程序，为嘛不用呢！哈哈，个人看法！下面进入正题： C+...[详细]
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