LTC2489 Datasheet, PDF (1/24 Pages) Linear Technology – 16-Bit 2-/4-Channel ADC with Easy Drive Input Current Cancellation and I2C Interface

LTC2489
16-Bit 2-/4-Channel
ΔΣ ADC with Easy Drive Input Current
Cancellation and I²C Interface
FEATURES
■ _{Up to 2 Differential or 4 Single-Ended Inputs}
■ _{Easy Drive}^TM _{Technology Enables Rail-to-Rail}
Inputs with Zero Differential Input Current
■ _{Directly Digitizes High Impedance Sensors with}
Full Accuracy
■ _{2-Wire I}²_{C Interface with 9 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 4mm × 3mm DFN Package}
APPLICATIONS
■ _{Direct Sensor Digitizer}
■ _{Direct Temperature Measurement}
■ _{Instrumentation}
■ _{Industrial Process Control}
DESCRIPTION
The LTC^®2489 is a 4-channel (2-channel differential),
16-bit, No Latency ΔΣ™ ADC with Easy Drive technology
and a 2-wire, I²C interface. The patented sampling scheme
eliminates dynamic input current errors and the shortcom-
ings 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 com-
binations of 4 analog input channels operating in single-
ended or differential modes. It automatically rejects line
frequencies of 50Hz and 60Hz simultaneously.
The LTC2489 allows a wide, common mode input range
(0V to V_CC), 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 ΔΣ 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
4-CHANNEL
MUX
CH2
CH3
COM
V_CC
0.1μF
10μF
REF⁺
IN⁺
16-BIT ΔΣ ADC SDA
WITH EASY-DRIVE SCL
IN^–
REF ^–
CA1
CA0
F_O
OSC
2489 TA01a
1.7k
2-WIRE
I²C INTERFACE
9-PIN SELECTABLE
ADDRESSES
+FS Error vs R_SOURCE at IN⁺ and IN^–
80
V_CC = 5V
60
40
VVV^{RIINNE+–F}
=
=
=
5V
3.75V
1.25V
F_O = GND
20 ^{TA = 25°C}
0
C_IN = 1μF
–20
–40
–60
–80
1
10
100
1k
10k 100k
R_SOURCE (Ω)
2489 TA01b
2489f
1