Datasheet

LTC2481
1
2481fc
TYPICAL APPLICATION
FEATURES DESCRIPTION
16-Bit ΔΣ ADC with Easy Drive
Input Current Cancellation
and I
2
C Interface
The LTC
®
2481 combines a 16-bit plus sign No Latency ΔΣ
™
analog-to-digital converter with patented Easy Drive
technology and I
2
C digital 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 input signals, with rail-to-
rail input range to be directly digitized while maintaining
exceptional DC accuracy.
The LTC2481 includes on-chip programmable gain, a
temperature sensor and an oscillator. The LTC2481 can
be confi gured through an I
2
C interface to provide a pro-
grammable gain from 1 to 256 in 8 steps, to digitize an
external signal or internal temperature sensor, reject line
frequencies (50Hz, 60Hz or simultaneous 50Hz/60Hz) as
well as a 2x speed-up mode.
The LTC2481 allows a wide common mode input range
(0V to V
CC
) independent of the reference voltage. The
reference can be as low as 100mV or can be tied directly
to V
CC
. The LTC2481 includes an on-chip trimmed oscil-
lator eliminating the need for external crystals or oscil-
lators. Absolute accuracy and low drift are automatically
maintained through continuous, transparent, offset and
full-scale calibration.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No Latency ∆∑ and Easy Drive are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patents Pending.
+FS Error vs R
SOURCE
at IN
+
and IN
–
APPLICATIONS
n
Easy Drive
™
Technology Enables Rail-to-Rail Inputs
with Zero Differential Input Current
n
Directly Digitizes High Impedance Sensors with
Full Accuracy
n
Programmable Gain from 1 to 256
n
Integrated Temperature Sensor
n
GND to V
CC
Input/Reference Common Mode Range
n
2-Wire I
2
C Interface
n
Programmable 50Hz, 60Hz or Simultaneous
50Hz/60Hz Rejection Mode
n
2ppm (0.25LSB) INL, No Missing Codes
n
1ppm Offset and 15ppm Full-Scale Error
n
Selectable 2x Speed Mode
n
No Latency: Digital Filter Settles in a Single Cycle
n
Single Supply 2.7V to 5.5V Operation
n
Internal Oscillator
n
Six Addresses Available and One Global Address for
Synchronization
n
Available in a Tiny (3mm × 3mm) 10-Lead DFN Package
n
Direct Sensor Digitizer
n
Weight Scales
n
Direct Temperature Measurement
n
Strain Gauge Transducers
n
Instrumentation
n
Industrial Process Control
n
DVMs and Meters
LTC2481
V
IN
+
REF
+
V
CC
V
CC
GND
V
IN
–
1µF
SDA
2-WIRE
I
2
C INTERFACE
0.1µF
0.1µF
10k
I
DIFF
= 0
10k
CA0/f
0
2481 TA01a
CA1
SCL
6 ADDRESSES
REF
–
SENSE
R
SOURCE
()
1
+FS ERROR (ppm)
–20
0
20
1k
100k
2481 TA01b
–40
–60
–80
10 100 10k
40
60
80
V
CC
= 5V
V
REF
= 5V
V
IN
+
= 3.75V
V
IN
–
= 1.25V
f
O
= GND
T
A
= 25°C
C
IN
= 1µF