LTC2431_15 Datasheet, PDF (1/40 Pages) Linear Technology – 20-Bit No Latency ADCs with Differential Input and Differential Reference

LTC2430/LTC2431
20-Bit No Latency ∆Σ^TM ADCs
with Differential Input and
Differential Reference
FEATURES
s _{Low Supply Current (200µA in Conversion Mode}
and 4µA in Autosleep Mode)
s _{Differential Input and Differential Reference}
with GND to V_CC Common Mode Range
s _{3ppm INL, No Missing Codes}
s _{10ppm Full-Scale Error and 1ppm Offset}
s _{0.56ppm Noise, 20.8 ENOBs}
s _{No Latency: Digital Filter Settles in a Single Cycle.}
Each Conversion Is Accurate, Even After an
Input Step
s _{Single Supply 2.7V to 5.5V Operation}
s _{Internal Oscillator—No External Components}
Required
s _{110dB Min, 50Hz/60Hz Notch Filter}
s _{Pin Compatible with 24-Bit LTC2410/LTC2411}
U
APPLICATIO S
s _{Direct Sensor Digitizer}
s _{Weight Scales}
s _{Direct Temperature Measurement}
s _{Gas Analyzers}
s _{Strain Gauge Transducers}
s _{Instrumentation}
s _{Data Acquisition}
s _{Industrial Process Control}
s _{DVMs and Meters}
DESCRIPTIO
The LTC^®2430/LTC2431 are 2.7V to 5.5V micropower
20-bit differential ∆Σ analog-to-digital converters with an
integrated oscillator, 3ppm INL and 0.56ppm RMS noise.
They use delta-sigma technology and provide single cycle
settling time for multiplexed applications. Through a
single pin, the LTC2430/LTC2431 can be configured for
better than 110dB differential mode rejection at 50Hz or
60Hz ±2%, or they can be driven by an external oscillator
for a user-defined rejection frequency. The internal oscil-
lator requires no external frequency setting components.
The converters accept any external differential reference
voltage from 0.1V to V_CC for flexible ratiometric and
remote sensing measurement configurations. The full-
scale differential input range is from – 0.5V_REF to 0.5V_REF.
The reference common mode voltage, V_REFCM, and the
input common mode voltage, V_INCM, may be indepen-
dently set anywhere within GND to V_CC. The DC common
mode input rejection is better than 120dB.
The LTC2430/LTC2431 communicate through a flexible
3-wire digital interface that is compatible with SPI and
MICROWIRE^TM protocols.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency ∆Σ is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
TYPICAL APPLICATIO S
V_OUT
3V TO 5V
4.7µF
0.1µF
ANALOG INPUT RANGE
–0.5V_REF TO 0.5V_REF
(V_OUT + 0.25V) TO 20V
6
4
LT1790
1
2
0.1µF
V_CC
F_O
LTC2431
REF⁺
SCK
REF^–
IN⁺
IN^–
GND
SDO
CS
24301 TA01
V_CC
= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION
3-WIRE
SPI INTERFACE
Total Unadjusted Error
(V_CC = 5V, V_REF = 5V)
5
V_CC = 5V
4 V_REF = 5V
3
V_INCM = V_INCM = 2.5V
F_O = GND
2
25°C
1
85°C
0
–1
–45°C
–2
–3
–4
–5
–2.5 –2 –1.5 –1 – 0.5 0 0.5 1 1.5 2 2.5
INPUT VOLTAGE (V)
24301 G01
24301f
1