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Linear Technology |
LTC2497
16-Bit 8-/16-Channel
ΔΣ ADC with Easy Drive Input Current
Cancellation and I2C Interface
FEATURES
■ 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
www■.Da2t-aWShireeetI42UC.cIonmterface with 27 Addresses Plus One
Global Address for Synchronization
■ 600nV RMS Noise (0.02LSB Transition Noise)
■ GND to VCC Input/Reference Common Mode Range
■ Simultaneous 50Hz/60Hz Rejection
■ 2ppm INL, No Missing Codes
■ 1ppm Offset and 15ppm Full-Scale Error
■ 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
DESCRIPTION
The LTC®2497 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 LTC2497 includes 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. It automatically rejects line
frequencies of 50Hz and 60Hz simultaneously.
The LTC2497 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 enables
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
Easy Drive Data Acquisition System
2.7V TO 5.5V
CH0
CH1
•
•
•
CH7
CH8
•
•
•
CH15
COM
16-CHANNEL
MUX
MUXOUT/
ADCIN
VCC
REF+
IN+
16-BIT ∆Σ ADC
WITH EASY DRIVE
IN–
REF –
SDA
SCL
MUXOUT/
ADCIN
OSC
FO
2497 TA01
10µF
0.1µF
1.7k
2-WIRE
I2C INTERFACE
+FS Error vs RSOURCE at IN+ and IN–
80
VCC = 5V
60
40
VVVRIINNE+–F
=
=
=
5V
3.75V
1.25V
FO = GND
20 TA = 25°C
0
CIN = 1µF
–20
–40
–60
–80
1
10 100 1k 10k 100k
RSOURCE (Ω)
2497 TA01b
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LTC2497
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Supply Voltage (VCC) ................................... –0.3V to 6V
Analog Input Voltage
(CH0-CH15, COM) ....................–0.3V to (VCC + 0.3V)
REF+, REF–................................–0.3V to (VCC + 0.3V)
ADCINN, ADCINP,
MUXOUTP MUXOUTN ..............–0.3V to (VCC + 0.3V)
Digital Input Voltage......................–0.3V to (VCC + 0.3V)
Digital Output Voltage ...................–0.3V to (VCC + 0.3V)
Operating Temperature Range
www.DaLTtaCS2he4e9t74CU.c..o..m............................................. 0ºC to 70ºC
LTC2497I ..............................................–40ºC to 85ºC
Storage Temperature Range....................–65ºC to 150ºC
PACKAGE/ORDER INFORMATION
TOP VIEW
GND 1
SCL 2
SDA 3
GND 4
NC 5
GND 6
COM 7
CH0 8
CH1 9
CH2 10
CH3 11
CH4 12
38 37 36 35 34 33 32
39
13 14 15 16 17 18 19
31 GND
30 REF–
29 REF+
28 VCC
27 MUXOUTN
26 ADCINN
25 ADCINP
24 MUXOUTP
23 CH15
22 CH14
21 CH13
20 CH12
UHF PACKAGE
38-LEAD (5mm × 7mm) PLASTIC QFN
TJMAX = 125°C, θJA = 34°C/W
EXPOSED PAD (PIN #39) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER QFN PART MARKING*
LTC2497CUHF
LTC2497IUHF
2497
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is defined by a label on the shipping container.
2497f
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