ADS1218
ADS1218
SBAS187 – SEPTEMBER 2001
8-Channel, 24-Bit
ANALOG-TO-DIGITAL CONVERTER
with FLASH Memory
DESCRIPTION
FEATURES
● 24 BITS NO MISSING CODES
● 0.0015% INL
The ADS1218 is a precision, wide dynamic range, delta-sigma, Analog-to-
Digital(A/D)converterwith24-bitresolutionandFLASHmemoryoperating
from 2.7V to 5.25V supplies. The delta-sigma, A/D converter provides up to
24 bits of no missing code performance and effective resolution of 22 bits.
● 22 BITS EFFECTIVE RESOLUTION
(PGA = 1), 19 BITS (PGA = 128)
The eight input channels are multiplexed. Internal buffering can be selected
to provide a very high input impedance for direct connection to transducers
or low-level voltage signals. Burn out current sources are provided that allow
for the detection of an open or shorted sensor. An 8-bit Digital-to-Analog (D/
A) converter provides an offset correction with a range of 50% of the FSR
(Full-Scale Range).
● 4K BYTES OF FLASH MEMORY
PROGRAMMABLE FROM 2.7V TO 5.25V
● PGA FROM 1 TO 128
● SINGLE CYCLE SETTLING MODE
● PROGRAMMABLE DATA OUTPUT RATES
UP TO 1kHz
The PGA (Programmable Gain Amplifier) provides selectable gains of 1 to
128 with an effective resolution of 19 bits at a gain of 128. The A/D
conversion is accomplished with a second-order delta-sigma modulator and
programmable sinc filter. The reference input is differential and can be used
for ratiometric conversion. The on-board current DACs (Digital-to-Analog
Converters) operate independently with the maximum current set by an
external resistor.
●
PRECISION ON-CHIP 1.25V/2.5V REFERENCE:
ACCURACY: 0.2%
DRIFT: 5ppm/°C
● EXTERNAL DIFFERENTIAL REFERENCE
OF 0.1V TO 2.5V
● ON-CHIP CALIBRATION
● PIN COMPATIBLE WITH ADS1216
● SPI™ COMPATIBLE
The serial interface is SPI compatible. Eight bits of digital I/O are also provided
thatcanbeusedforinputoroutput. TheADS1218isdesignedforhigh-resolution
measurement applications in smart transmitters, industrial process control, weight
scales, chromatography, and portable instrumentation.
● 2.7V TO 5.25V
● < 1mW POWER CONSUMPTION
AGND AVDD
RDAC
VREFOUT
VRCAP
VREF+
VREF–
XIN
XOUT
8-Bit
IDAC
IDAC2
IDAC1
APPLICATIONS
Clock Generator
1.25V or
2.5V
Reference
8-Bit
IDAC
● INDUSTRIAL PROCESS CONTROL
● LIQUID/GAS CHROMATOGRAPHY
● BLOOD ANALYSIS
AVDD
2µA
Offset
DAC
● SMART TRANSMITTERS
● PORTABLE INSTRUMENTATION
● WEIGHT SCALES
AIN
AIN
0
1
A = 1:128
PGA
Registers
RAM
IN+
AIN2
Program-
mable
Digital
Filter
2nd-Order
Modulator
AIN
AIN
AIN
AIN
AIN
3
4
5
6
7
MUX
+
Controller
BUF
IN–
● PRESSURE TRANSDUCERS
4K Bytes
FLASH
WREN
POL
SPI is a registered trademark of Motorola.
AINCOM
SCLK
DIN
Serial Interface
RESET DRDY
2µA
Digital I/O
Interface
DOUT
AGND
CS
DVDD
DGND BUFEN
D0 ... D7
PDWN DSYNC
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright © 2001, Texas Instruments Incorporated
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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