LTC2435 Datasheet, PDF (1/40 Pages) Linear Technology – 20-Bit No Latency ADCs with Differential Input and Differential Reference

LTC2435/LTC2435-1
20-Bit No Latency ∆Σ^TM
ADCs with Differential Input and
Differential Reference
FEATURES
■ _{2× Speed Up Version of the LTC2430: 15Hz Output}
Rate, 60Hz Notch—LTC2435; 13.75Hz Output Rate,
Simultaneous 50Hz/60Hz Notch—LTC2435-1
■ _{Differential Input and Differential Reference with}
GND to V_CC Common Mode Range
■ _{3ppm INL, No Missing Codes}
■ _{10ppm Gain Error}
■ _{0.8ppm Noise}
■ _{Single Conversion Settling Time for Multiplexed}
Applications
■ _{Internal Oscillator—No External Components}
Required
■ _{Single Supply 2.7V to 5.5V Operation}
■ _{Low Supply Current (200µA,4µA in Auto Sleep)}
■ _{20-Bit ADC in Narrow SSOP-16 Package}
(SO-8 Footprint)
U
APPLICATIO S
■ _{Direct Sensor Digitizer}
■ _{Weight Scales}
■ _{Direct Temperature Measurement}
■ _{Gas Analyzers}
■ _{Strain Gage Transducers}
■ _{Instrumentation}
■ _{Data Acquisition}
■ _{Industrial Process Control}
■ _{6-Digit DVMs}
DESCRIPTIO
The LTC^®2435/2435-1 are 2.7V to 5.5V micropower
20-bit differential ∆Σ analog to digital converters with
integrated oscillator, 3ppm INL and 0.8ppm RMS noise.
They use delta-sigma technology and provide single cycle
settling time for multiplexed applications. Through a
single pin, the LTC2435 can be configured for better than
110dB input differential mode rejection at 50Hz or 60Hz
±2%, or it can be driven by an external oscillator for a user
defined rejection frequency. The LTC2435-1 can be con-
figured for better than 87dB input differential mode rejec-
tion over the range of 49Hz to 61.2Hz (50Hz and 60Hz
±2% simultaneously). The internal oscillator 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 the GND to V_CC range of the
LTC2435/LTC2435-1. The DC common mode input rejec-
tion is better than 120dB.
The LTC2435/LTC2435-1 communicate 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.
Protected by U.S. Patents including 6140950, 6169506.
TYPICAL APPLICATIO S
2.7V TO 5.5V
1µF
REFERENCE
VOLTAGE
0.1V TO V_CC
2
V_CC
14
F_O
LTC2435/
LTC2435-1
3 _REF+
4 _REF–
13
SCK
ANALOG INPUT RANGE
–0.5V_REF TO 0.5V_REF
5 _IN+
6 _IN–
1, 7, 8, 9, 10, 15, 16 _GND
12
SDO
11
CS
V_CC
= INTERNAL OSC/50Hz REJECTION (LTC2435)
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION (LTC2435)
= INTERNAL 50Hz/60Hz REJECTION (LTC2435-1)
3-WIRE
SPI INTERFACE
2435 TA01
Integral Nonlinearity vs Input
10
8
6
4
2
T_A = 25°C
0
T_A = 85°C
–2
T_A = –45°C
–4
–6
F_O = GND
V_CC = 5V
–8 ^VREF ^{= 5V}
V_INCM = V_INCM = 2.5V
–10
–2.5 –1.5 –0.5 0.5
1.5
2.5
INPUT VOLTAGE (V)
2435 G04
24351fa
1