LTC2499 Datasheet, PDF (1/32 Pages) Linear Technology – 24-Bit 8-/16-Channel ΔΣ ADC with Easy Drive Input Current Cancellation and I2C Interface

LTC2499
24-Bit 8-/16-Channel
ΔΣ ADC with Easy Drive Input Current
Cancellation and I²C Interface
FEATURES
DESCRIPTION
n _{Up to Eight Differential or 16 Single-Ended Inputs}
n _{Easy Drive™ Technology Enables Rail-to-Rail}
Inputs with Zero Differential Input Current
n _{Directly Digitizes High Impedance Sensors with}
Full Accuracy
n _{2-Wire I}²_{C Interface with 27 Addresses Plus One}
Global Address for Synchronization
n _{600nV RMS Noise}
n _{Integrated High Accuracy Temperature Sensor}
n _{GND to VCC Input/Reference Common Mode Range}
n _{Programmable 50Hz, 60Hz or Simultaneous 50Hz/}
60Hz Rejection Mode
n _{2ppm INL, No Missing Codes}
n _{1ppm Offset and 15ppm Full-Scale Error}
n _{2x Speed/Reduced Power Mode (15Hz Using Internal}
Oscillator and 80μA at 7.5Hz Output)
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 5mm × 7mm QFN Package}
APPLICATIONS
n _{Direct Sensor Digitizer}
n _{Direct Temperature Measurement}
n _{Instrumentation}
n _{Industrial Process Control}
The LTC^®2499 is a 16-channel (eight differential), 24-bit,
No Latency ΔΣ™ 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 LTC2499 includes a high accuracy, temperature
sensor and an integrated oscillator. This device can be
configured to measure an external signal (from combi-
nations of 16 analog input channels operating in single-
ended or differential modes) or its internal temperature
sensor. The integrated temperature sensor offers 1/30th
°C resolution and 2°C absolute accuracy.
The LTC2499 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 en-
ables optional external amplifiers to be shared between all
analog inputs and auto calibration continuously removes
their associated offset and drift.
L, LT, LTC and LTM 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.
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/
V_CC
ADCIN
REF⁺
IN⁺
24-BIT ΔΣ ADC ^SDA
WITH EASY DRIVE _SCL
IN^–
REF^–
MUXOUT/
ADCIN
OSC
F_O
2499 TA01
10μF
0.1μF
1.7k
2-WIRE
I²C INTERFACE
Integrated 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
2499 TA02
2499fb
1