LTC2489
16-Bit 2-/4-Channel DΣ ADC
with Easy Drive Input Current
Cancellation and I2C Interface
Description
Features
Up to 2 Differential or 4 Single-Ended Inputs
n Easy DriveTM Technology Enables Rail-to-Rail
Inputs with Zero Differential Input Current
n Directly Digitizes High Impedance Sensors with
Full Accuracy
n 2-Wire I2C Interface with 9 Addresses Plus One
Global Address for Synchronization
n 600nV RMS Noise (0.02LSB Transition Noise)
n GND to V
CC Input/Reference Common Mode Range
n Simultaneous 50Hz/60Hz Rejection
n 2ppm INL, No Missing Codes
n 1ppm Offset and 15ppm Full-Scale Error
n No Latency: Digital Filter Settles in a Single Cycle,
Even After a New Channel is Selected
n Single Supply, 2.7V to 5.5V Operation (0.8mW)
n Internal Oscillator
n Tiny 4mm × 3mm DFN Package
n
Applications
Direct Sensor Digitizer
Direct Temperature Measurement
n Instrumentation
n Industrial Process Control
n
n
The LTC®2489 is a 4-channel (2-channel differential),
16-bit, No Latency DS™ ADC with Easy Drive technology
and a 2-wire, I2C interface. The patented sampling scheme
eliminates 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 LTC2489 includes an integrated oscillator. This device
can be configured to measure an external signal from combinations of 4 analog input channels operating in singleended or differential modes. It automatically rejects line
frequencies of 50Hz and 60Hz simultaneously.
The LTC2489 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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Easy Drive and No Latency ∆Σ are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Typical Application
+FS Error vs RSOURCE at IN+ and IN–
Data Acquisition System with Temperature Compensation
2.7V TO 5.5V
CH3
COM
4-CHANNEL
MUX
IN+
REF+
1.7k
REF–
SDA
SCL
2-WIRE
I2C INTERFACE
CA1
CA0
16-BIT ∆Σ ADC
WITH EASY-DRIVE
IN–
10µF
9-PIN SELECTABLE
ADDRESSES
fO
OSC
2489 TA01a
+FS ERROR (ppm)
0.1µF
VCC
CH0
CH1
CH2
80
VCC = 5V
60 VREF = 5V
VIN+ = 3.75V
VIN– = 1.25V
40
fO = GND
20 TA = 25°C
CIN = 1µF
0
–20
–40
–60
–80
1
10
100
1k
RSOURCE (Ω)
10k
100k
2489 TA01b
2489fb
For more information www.linear.com/LTC2489
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