Datasheet

LTC2430/LTC2431
1
24301f
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 LTC 2430/LTC2431 communicate through a flexible
3-wire digital interface that is compatible with SPI and
MICROWIRE
TM
protocols.
■
Direct Sensor Digitizer
■
Weight Scales
■
Direct Temperature Measurement
■
Gas Analyzers
■
Strain Gauge Transducers
■
Instrumentation
■
Data Acquisition
■
Industrial Process Control
■
DVMs and Meters
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Low Supply Current (200µA in Conversion Mode
and 4µA in Autosleep Mode)
■
Differential Input and Differential Reference
with GND to V
CC
Common Mode Range
■
3ppm INL, No Missing Codes
■
10ppm Full-Scale Error and 1ppm Offset
■
0.56ppm Noise, 20.8 ENOBs
■
No Latency: Digital Filter Settles in a Single Cycle.
Each Conversion Is Accurate, Even After an
Input Step
■
Single Supply 2.7V to 5.5V Operation
■
Internal Oscillator—No External Components
Required
■
110dB Min, 50Hz/60Hz Notch Filter
■
Pin Compatible with 24-Bit LTC2410/LTC2411
20-Bit No Latency ∆Σ
TM
ADCs
with Differential Input and
Differential Reference
No Latency ∆Σ is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
V
CC
F
O
64
12
REF
+
REF
–
SCK
IN
+
IN
–
SDO
GND
CS
ANALOG INPUT RANGE
–0.5V
REF
TO 0.5V
REF
3-WIRE
SPI INTERFACE
0.1µF
0.1µF
LTC2431
24301 TA01
4.7µF
= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION
V
CC
LT1790
(V
OUT
+ 0.25V) TO 20V
V
OUT
3V TO 5V
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO S
U
INPUT VOLTAGE (V)
–2.5
TUE (ppm OF V
REF
)
1
3
5
1.5
24301 G01
–1
–3
0
2
4
–2
–4
–5
–1.5–2
–0.5–1
0.5 1 2
0
2.5
V
CC
= 5V
V
REF
= 5V
V
INCM
= V
INCM
= 2.5V
F
O
= GND
85°C25°C
–45°C
Total Unadjusted Error
(V
CC
= 5V, V
REF
= 5V)