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PDF LTC2495 Data sheet ( Hoja de datos )
| Número de pieza | LTC2495 | |
| Descripción | No Latency ADC | |
| Fabricantes | Linear Integrated Systems | |
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Hay una vista previa y un enlace de descarga de LTC2495 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
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LTC2495
FEATURES
16-Bit 8-/16-Channel
ΔΣ ADC with PGA, Easy Drive
and I2C Interface
DESCRIPTION
■ Up to Eight Differential or 16 Single-Ended Inputs
■ Easy DriveTM Technology Enables Rail-to-Rail
Inputs with Zero Differential Input Current
■ Directly Digitizes High Impedance Sensors with
Full Accuracy
■ 2-Wire I2C Interface with 27 Addresses Plus One
Global Address for Synchronization
■ 600nV RMS Noise
■ Programmable Gain from 1 to 256
■ Integrated High Accuracy Temperature Sensor
■ GND to VCC Input/Reference Common Mode Range
■ Programmable 50Hz, 60Hz, or Simultaneous 50Hz/
60Hz Rejection Mode
■ 2ppm INL, No Missing Codes
■ 1ppm Offset and 15ppm Full-Scale Error
■ 2x Speed/Reduced Power Mode (15Hz Using Internal
Oscillator and 80µA at 7.5Hz Output)
■ No Latency: Digital Filter Settles in a Single Cycle,
Even After a New Channel is Selected
■ Single Supply 2.7V to 5.5V Operation (0.8mW)
■ Internal Oscillator
■ Tiny 5mm × 7mm QFN Package
APPLICATIONS
■ Direct Sensor Digitizer
■ Direct Temperature Measurement
■ Instrumentation
■ Industrial Process Control
The LTC®2495 is a 16-channel (eight differential), 16-bit,
No Latency ΔΣTM ADC with Easy Drive technology and a
2-wire, I2C interface. The patented sampling scheme elimi-
nates dynamic input current errors and the shortcomings
of on-chip buffering through automatic cancellation of
differential input current. This allows large external source
impedances and rail-to-rail input signals to be directly
digitized while maintaining exceptional DC accuracy.
The LTC2495 includes programmable gain, a high accuracy
temperature sensor, and an integrated oscillator. This device
can be configured to measure an external signal (from com-
binations of 16 analog input channels operating in single-
ended or differential modes) or its internal temperature
sensor. The integrated temperature sensor offers 1/2°C
resolution and 2°C absolute accuracy. The LTC2495 can
be configured to provide a programmable gain from 1 to
256 in 8 steps.
The LTC2495 allows a wide common mode input range
(0V to VCC), independent of the reference voltage. Any
combination of single-ended or differential inputs can
be selected and the first conversion, after a new channel
is selected, is valid. Access to the multiplexer output en-
ables optional external amplifiers to be shared between all
analog inputs and auto calibration continuously removes
their associated offset and drift.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
No Latency ∆Σ and Easy Drive are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Data Acquisition System with Temperature Compensation
2.7V TO 5.5V
CH0
CH1
•
•
•
CH7
CH8
•
•
•
CH15
COM
16-CHANNEL
MUX
TEMPERATURE
SENSOR
MUXOUT/
ADCIN
VCC
REF+
IN+
16-BIT ∆Σ ADC
WITH EASY DRIVE
IN–
REF –
SDA
SCL
MUXOUT/
ADCIN
OSC
FO
2495 TA01
0.1µF
10µF
1.7k
2-WIRE
I2C INTERFACE
Built-In High Performance Temperature Sensor
5
4
3
2
1
0
–1
–2
–3
–4
–5
–55 –30
–5 20 45 70
TEMPERATURE (°C)
95 120
2495 TA02
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LTC2495
POWER REQUIREMENTS The ● denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at TA = 25°C. (Note 3)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
UNITS
VCC Supply Voltage
ICC Supply Current
Conversion Current (Note 11)
Temperature Measurement (Note 11)
Sleep Mode (Note 11)
● 2.7
5.5
● 160 275
● 200 300
● 12
V
µA
µA
µA
DIGITAL INPUTS AND DIGITAL OUTPUTS The ● denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
fEOSC
tHEO
tLEO
tCONV_1
tCONV_2
External Oscillator Frequency Range
External Oscillator High Period
External Oscillator Low Period
Conversion Time for 1x Speed Mode
Conversion Time for 2x Speed Mode
(Note 16)
50Hz Mode
60Hz Mode
Simultaneous 50Hz/60Hz Mode
External Oscillator (Note 10)
50Hz Mode
60Hz Mode
Simultaneous 50Hz/60Hz Mode
External Oscillator (Note 10)
● 10
4000
● 0.125
100
● 0.125
100
● 157.2
160.3
163.5
● 131
133.6
136.3
● 144.1
146.9
149.9
41036/fEOSC (in kHz)
● 78.7 80.3 81.9
● 65.6 66.9 68.2
● 72.2 73.6 75.1
20556/fEOSC (in kHz)
kHz
µs
µs
ms
ms
ms
ms
ms
ms
ms
ms
I2C TIMING CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 3, 15)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
fSCL SCL Clock Frequency
tHD(SDA) Hold Time (Repeated) Start Condition
tLOW Low Period of the SCL Pin
tHIGH High Period of the SCL Pin
tSU(STA)
Set-Up Time for a Repeated Start Condition
tHD(DAT)
Data Hold Time
tSU(DAT)
Data Set-Up Time
tr Rise Time for SDA Signals
(Note 14)
tf Fall Time for SDA Signals
(Note 14)
tSU(STO)
Set-Up Time for Stop Condition
tBUF Bus Free Time Between a Second Start Condition
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.
Note 3: Unless otherwise specified: VCC = 2.7V to 5.5V
VREFCM = VREF/2, FS = 0.5VREF/Gain
wheVreININ= +INa+nd– IINN––,aVreINt(hCeM)se=le(cINte+d–inINpu–)t/c2h, annels.
Note 4: Use internal conversion clock or external conversion clock source
with fEOSC = 307.2kHz unless otherwise specified.
Note 5: Guaranteed by design, not subject to test.
Note 6: 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.
●0
400 kHz
● 0.6
µs
● 1.3
µs
● 0.6
µs
● 0.6
µs
●0
0.9 µs
● 100
ns
● 20 + 0.1CB
● 20 + 0.1CB
● 0.6
300 ns
300 ns
µs
● 1.3
µs
Note 7: 50Hz mode (internal oscillator) or fEOSC = 256kHz ±2% (external oscillator).
Note 8: 60Hz mode (internal oscillator) or fEOSC = 307.2kHz ±2% (external oscillator).
Note 9: Simultaneous 50Hz/60Hz mode (internal oscillator) or fEOSC =
280kHz ±2% (external oscillator).
Note 10: The external oscillator is connected to the FO pin. The external
oscillator frequency, fEOSC, is expressed in kHz.
Note 11: The converter uses its internal oscillator.
Note 12: The output noise includes the contribution of the internal
calibration operations.
Note 13: Guaranteed by design and test correlation.
Note 14: CB = capacitance of one bus line in pF (10pF ≤ CB ≤ 400pF).
Note 15: All values refer to VIH(MIN) and VIL(MAX) levels.
Note 16: Refer to Applications Information section for Performance vs
Data Rate graphs.
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LTC2495
PIN FUNCTIONS
ADCINN (Pin 26): Negative ADC Input. Connect to the
output of a buffer/amplifier driven by MUXOUTN or short
directly to MUXOUTN.
MUXOUTN (Pin 27): Negative Multiplexer Output. Con-
nect to the input of an external buffer/amplifier or short
directly to ADCINN.
VCC (Pin 28): Positive Supply Voltage. Bypass to GND with
a 10µF tantalum capacitor in parallel with a 0.1µF ceramic
capacitor as close to the part as possible.
REF+, REF– (Pin 29, Pin 30): Differential Reference Input.
The voltage on these pins can have any value between
GND and VCC as long as the reference positive input,
REF+, remains more positive than the negative reference
input, REF–, by at least 0.1V. The differential voltage (VREF
= REF+ – REF–) sets the full-scale range (–0.5 • VREF/Gain
to 0.5 • VREF/Gain) for all input channels.
FO (Pin 35): Frequency Control Pin. Digital input that
controls the internal conversion clock rate. When FO is
connected to GND, the converter uses its internal oscil-
lator running at 307.2kHz. The conversion clock may
also be overridden by driving the FO pin with an external
clock in order to change the output rate and the digital
filter rejection null.
CA0, CA1, CA2 (Pins 36, 37, 38): Chip Address Control
Pins. These pins are configured as a three-state (LOW,
HIGH, Floating) address control bits for the device I2C
address.
Exposed Pad (Pin 39): Ground. This pin is ground and
must be soldered to the PCB ground plane. For prototyping
purposes, this pin may remain floating.
FUNCTIONAL BLOCK DIAGRAM
TEMP
SENSOR
VCC
GND
REF+
REF –
MUXOUTP ADCINP
CH0
CH1
CH15
COM
•
•
•
MUX
–+
DIFFERENTIAL
3RD ORDER
∆Σ MODULATOR
MUXOUTN ADCINN
AUTOCALIBRATION
AND CONTROL
INTERNAL
OSCILLATOR
FO
(INT/EXT)
DECIMATING FIR
ADDRESS
I2C
2-WIRE
INTERFACE
2495 BD
SDA
SCL
2495f
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| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTC2495.PDF ] | |
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