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PDF LTC2451 Data sheet ( Hoja de datos )
| Número de pieza | LTC2451 | |
| Descripción | 16-Bit DS ADC | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC2451 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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FEATURES
n GND to VCC Single-Ended Input Range
n 0.02LSB RMS Noise
n 2LSB INL, No Missing Codes
n 1LSB Offset Error
n 4LSB Full-Scale Error
n Programmable 30/60 Conversions per Second
n Single Conversion Settling Time for Multiplexed
Applications
n Single-Cycle Operation with Auto Shutdown
n 400μA Supply Current
n 0.2μA Sleep Current
n Internal Oscillator—No External Components Required
n Single Supply, 2.7V to 5.5V Operation
n 2-Wire I2C Interface
n Ultra-Tiny 3mm × 2mm DFN or TSOT-23 Package
APPLICATIONS
n System Monitoring
n Environmental Monitoring
n Direct Temperature Measurements
n Instrumentation
n Industrial Process Control
n Data Acquisition
n Embedded ADC Upgrades
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. No Latency Δ∑ and Easy Drive are 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.
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LTC2451
Ultra-Tiny, 16-Bit DS ADC
with I2C Interface
DESCRIPTION
The LTC®2451 is an ultra-tiny, 16-bit, analog-to-digital
converter. The LTC2451 uses a single 2.7V to 5.5V
supply, accepts a single-ended analog input voltage and
communicates through an I2C interface. The converter
is available in an 8-pin, 3mm × 2mm DFN 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 provides single-cycle
settling time for multiplexed applications. The LTC2451
includes a proprietary input sampling scheme that reduces
the average input sampling current several orders of
magnitude lower than conventional Δ∑ converters.
The LTC2451 is capable of up to 60 conversions per
second and, due to the very large oversampling ratio,
has extremely relaxed antialiasing requirements. In the
30Hz mode, the LTC2451 includes continuous internal
offset calibration algorithms which are transparent to the
user, ensuring accuracy over time and over the operating
temperature range. The converter has external REF+ and
REF– pins and the input voltage can range from VREF– to
VREF+. If VREF+ = VCC and VREF– = GND, the input voltage
can range from GND to VCC.
Following a single conversion, the LTC2451 can auto-
matically enter sleep mode and reduce its power to less
than 0.2μA. If the user reads the ADC once per second,
the LTC2451 consumes an average of less than 50μW
from a 2.7V supply.
TYPICAL APPLICATION
1k
SENSOR
2.7V TO 5.5V
0.1μF
10μF
REF+ VCC SCL
IN LTC2451
2-WIRE I2C
0.1μF
SDA INTERFACE
REF – GND
2451 TA01a
Integral Nonlinearity, VCC = 3V
3
2
1
0 TA = 90°C
–1
TA = – 45°C, 25°C
–2
–3
0
0.5 1 1.5 2 2.5 3
INPUT VOLTAGE (V)
2451 TA01b
2451ff
1
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LTC2451
TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C; graphs apply to both 30Hz and 60Hz modes, unless otherwise noted.
Maximum INL vs Temperature
5.0
4.5
4.0
3.5
3.0
2.5
2.0
VCC = 5V
VCC = 4.1V
1.5
1.0 VCC = 3V
0.5
0
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
2451 G04
Offset Error vs Temperature
30Hz Mode
0.50
0.45
0.40
0.35
0.30
0.25
0.20 VCC = 4.1V
0.15
VCC = 5V
0.10
0.05 VCC = 3V
0.00
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
2451 G05
Offset Error vs Temperature
60Hz Mode
0.50
0.45
0.40
0.35
0.30
0.25
0.20 VCC = 5V, 4.1V, 3V
0.15
0.10
0.05
0.00
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
2451 G06
Gain Error vs Temperature
10
9
8
7
6 VCC = 3V
5
4 VCC = 4.1V
3 VCC = 5V
2
1
0
–50 –25 0 25 50
TEMPERATURE (°C)
75 100
2451 G07
Transition Noise vs Temperature
3.0
2.5
2.0
1.5
1.0 VCC = 5V
0.5 VCC = 3V
0
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
2451 G08
Transition Noise vs Output Code
3.0
2.5
2.0
1.5
1.0 VCC = 5V
0.5 VCC = 3V
0
0 16384 32768 49152 65536
OUTPUT CODE
2451 G09
Conversion Mode Power Supply
Current vs Temperature
600
Sleep Mode Power Supply
Current vs Temperature
250
Average Power Dissipation vs
Temperature VCC = 3V, 30Hz Mode
10000
500
400 VCC = 5V
300
VCC = 3V
VCC = 4.1V
200
100
200
150
100
50
VCC = 5V
VCC = 4.1V
VCC = 3V
1000
100
10
25Hz OUTPUT SAMPLE RATE
10Hz OUTPUT SAMPLE RATE
1Hz OUTPUT SAMPLE RATE
0
–50 –25 0
25 50
TEMPERATURE (°C)
75 100
2451 G10
0
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
2451 G11
1
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
2451 G12
2451ff
5
5 Page 
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LTC2451
APPLICATIONS INFORMATION
Continuous Read/Write
Once the conversion cycle is concluded, the LTC2451 can
be written to, and then read from, using the Repeated Start
(Sr) command.
Figure 7 shows a cycle which begins with a data Write, a
Repeated Start, followed by a Read, and concluded with a
Stop command. The following conversion begins after all
16 bits are read out of the device, or after the Stop com-
mand, and uses the newly programmed configuration.
Discarding a Conversion Result and Initiating a New
Conversion with Optional Configuration Updating
At the conclusion of a conversion cycle, a Write cycle
can be initiated. Once the Write cycle is acknowledged, a
Stop (P) command initiates a new conversion. If a new
configuration is required, this data can be written into the
device and a Stop command initiates a new conversion
(see Figure 8).
Synchronizing the LTC2451 with the Global Address Call
The LTC2451 can also be synchronized with the global
address call (see Figure 9). To achieve this, the LTC2451
must first have completed the conversion cycle. The
master issues a Start, followed by the LTC2451 global
address 1110111, and a Write request. The LTC2451 will
be selected and acknowledge the request. If desired, the
master then sends the Write byte to program the 30Hz
or 60Hz mode. After the optional Write byte, the master
ends the Write operation with a Stop. This will update
the configuration registers (if a Write byte was sent) and
initiate a new conversion on the LTC2451, as shown in
Figure 9. In order to synchronize the start of the conver-
sion without affecting the configuration registers, the
Write operation can be aborted with a Stop. This initiates
a new conversion on the LTC2451 without changing the
configuration registers.
PRESERVING THE CONVERTER ACCURACY
The LTC2451 is designed to dramatically reduce the conver-
sion result’s sensitivity to device decoupling, PCB layout,
antialiasing circuits, line and frequency perturbations. Nev-
ertheless, in order to preserve the high accuracy capability
of this part, some simple precautions are desirable.
Digital Signal Levels
Due to the nature of CMOS logic, it is advisable to keep
input digital signals near GND or VCC. Voltages in the
CONVERSION
S
7-BIT ADDRESS
(0010100)
R ACK
READ
SLEEP
DATA OUTPUT
P
CONVERSION
S
7-BIT ADDRESS
(0010100)
R ACK
READ
SLEEP
DATAOUTPUT
Figure 6. Consecutive Reading at the Same Configuration
P
CONVERSION
2451 F06
CONVERSION
S
7-BIT ADDRESS
(0010100)
W ACK
WRITE
SLEEP
DATA INPUT
Sr
7-BIT ADDRESS
(0010100)
R ACK
READ
ADDRESS
DATA OUTPUT
Figure 7. Write, Read, Start Conversion
P
CONVERSION 2451 F05
CONVERSION
S
7-BIT ADDRESS
(0010100)
W ACK
WRITE
(OPTIONAL)
SLEEP
DATA INPUT
P
CONVERSION
2451 F08
Figure 8. Start a New Conversion without Reading Old Conversion Result
S
GLOBAL ADDRESS
(1110111)
W ACK WRITE (OPTIONAL)
SLEEP
DATA INPUT
P
CONVERSION
Figure 9. Synchronize the LTC2451 with the Global Address Call
2451 F09
2451ff
11
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet LTC2451.PDF ] | |
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