LTC2420 Datasheet, PDF (1/12 Pages) Linear Technology – 20-Bit uPower No Latency ADC in SO-8

Final Electrical Specifications
LTC2420
20-Bit µPower
No Latency ∆Σ^TM ADC in SO-8
FEATURES
DESCRIPTIO
January 2000
s _{20-Bit ADC in SO-8 Package}
s _{8ppm INL, No Missing Codes at 20 Bits}
s _{4ppm Full-Scale Error}
s _{0.5ppm Offset}
s _{1.2ppm Noise}
s _{Digital Filter Settles in a Single Cycle. Each}
Conversion Is Accurate, Even After an Input Step.
s _{Internal Oscillator—No External Components}
Required
s _{Fast Mode: 16-Bit Noise, 12 Bits TUE at 100sps}
s _{110dB Min, 50Hz/60Hz Notch Filter}
s _{Reference Input Voltage: 0.1V to VCC}
s _{Live Zero—Extended Input Range Accommodates}
12.5% Overrange and Underrange
s _{Single Supply 2.7V to 5.5V Operation}
s _{Low Supply Current (200µA) and Auto Shutdown}
s _{Pin Compatible with 24-Bit LTC2400}
U
APPLICATIO S
s _{Weight Scales}
s _{Direct Temperature Measurement}
s _{Gas Analyzers}
s _{Strain-Gage Transducers}
s _{Instrumentation}
s _{Data Acquisition}
s _{Industrial Process Control}
s _{4-Digit DVMs}
The LTC^®2420 is a micropower 20-bit A/D converter with
an integrated oscillator, 8ppm INL and 1.2ppm RMS
noise that operates from 2.7V to 5.5V. It uses delta-sigma
technology and provides a digital filter that settles in a
single cycle for multiplexed applications. Through a single
pin, the LTC2420 can be configured for better than 110dB
rejection at 50Hz or 60Hz ±2%, or it can be driven by an
external oscillator for a user-defined rejection frequency
in the range 1Hz to 800Hz. The internal oscillator requires
no external frequency setting components.
The converter accepts any external reference voltage from
0.1V to V_CC. With its extended input conversion range of
–12.5% V_REF to 112.5% V_REF, the LTC2420 smoothly
resolves the offset and overrange problems of preceding
sensors or signal conditioning circuits.
The LTC2420 communicates through a flexible 3-wire
digital interface which 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
2.7V TO 5.5V
1µF
1
V_CC
8
F_O
REFERENCE
VOLTAGE
0.1V TO V_CC
ANALOG
INPUT RANGE
–0.12V_REF TO 1.12V_REF
LTC2420
2 _VREF
SCK ⁷
3 _VIN
4 _GND
SDO ⁶
CS ⁵
V_CC
= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION
3-WIRE
SPI INTERFACE
2420 TA01
Total Unadjusted Error vs Output Code
10
8
V_CC = 5V
V_REF = 5V
6 ^{TA = 25°C}
F_O = LOW
4
2
0
–2
–4
–6
–8
–10
0
524,288
OUTPUT CODE (DECIMAL)
1,048,575
2420 TA02
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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