LTC2484 Datasheet, PDF (1/40 Pages) Linear Technology – 24-Bit ΔΣ ADC with Easy Drive Input Current Cancellation

LTC2484
24-Bit ∆Σ ADC with
Easy Drive Input Current Cancellation
FEATURES
■ _{Easy Drive Technology Enables Rail-to-Rail Inputs}
with Zero Differential Input Current
■ _{Directly Digitizes High Impedance Sensors with}
Full Accuracy
■ _{600nV RMS Noise}
■ _{Integrated Temperature Sensor}
■ _{GND to VCC Input/Reference Common Mode Range}
■ _{Programmable 50Hz, 60Hz or Simultaneous}
50Hz/60Hz Rejection Mode
■ _{2ppm INL, No Missing Codes}
■ _{1ppm Offset and 15ppm Total Unadjusted Error}
■ _{Selectable 2x Speed Mode (15Hz Using Internal}
Oscillator)
■ _{No Latency: Digital Filter Settles in a Single Cycle}
■ _{Single Supply 2.7V to 5.5V Operation}
■ _{Internal Oscillator}
■ _{Available in a Tiny (3mm × 3mm) 10-Lead}
DFN Package
U
APPLICATIO S
■ _{Direct Sensor Digitizer}
■ _{Weight Scales}
■ _{Direct Temperature Measurement}
■ _{Strain Gauge Transducers}
■ _{Instrumentation}
■ _{Industrial Process Control}
■ _{DVMs and Meters}
DESCRIPTIO
The LTC^®2484 combines a 24-bit No Latency ∆Σ™ analog-
to-digital converter with patented Easy Drive™ technol-
ogy. 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 LTC2484 includes an on-chip temperature sensor and
oscillator. The LTC2484 can be configured to measure an
external signal or internal temperature sensor and reject
line frequencies. 50Hz, 60Hz or simultaneous 50Hz/60Hz
line frequency rejection can be selected as well as a 2x
speed-up mode.
The LTC2484 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 LTC2484 includes an on-chip trimmed oscil-
lator, eliminating the need for external crystals or oscilla-
tors. Absolute accuracy and low drift are automatically
maintained through continuous, transparent, offset and
full-scale calibration.
, 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. Patent pending.
TYPICAL APPLICATIO
V_CC
1µF
10k
SENSE
10k
I_DIFF = 0
1µF
V_IN+ ^VREF
V_CC
LTC2484
V_IN–
GND
F_O
SDI
SDO
4-WIRE
SCK _{SPI INTERFACE}
CS
2484 TA01
+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)
2484 TA02
2484fa
1