ADS1218_14 Datasheet, PDF (1/45 Pages) Texas Instruments – 8-Channel, 24-Bit ANALOG-TO-DIGITAL CONVERTER with FLASH Memory

BurrĆBrown Products
from Texas Instruments
ADS1218
SBAS187C – SEPTEMBER 2001 – REVISED SEPTEMBER 2005
8-Channel, 24-Bit
ANALOG-TO-DIGITAL CONVERTER with FLASH Memory
FEATURES
• 24 BITS NO MISSING CODES
• 0.0015% INL
• 22 BITS EFFECTIVE RESOLUTION (PGA = 1),
19 BITS (PGA = 128)
• 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
• 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
• 2.7V TO 5.25V
• < 1mW POWER CONSUMPTION
APPLICATIONS
• INDUSTRIAL PROCESS CONTROL
• LIQUID/GAS CHROMATOGRAPHY
• BLOOD ANALYSIS
• SMART TRANSMITTERS
• PORTABLE INSTRUMENTATION
• WEIGHT SCALES
• PRESSURE TRANSDUCERS
DESCRIPTION
The ADS1218 is a precision, wide dynamic range,
delta-sigma, Analog-to-Digital (A/D) converter with
24-bit resolution and Flash memory operating 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.
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. Burnout 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).
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.
The serial interface is SPI-compatible. Eight bits of
digital I/O are also provided that can be used for input
or output. The ADS1218 is designed for
high-resolution measurement applications in smart
transmitters, industrial process control, weight scales,
chromatography, and portable instrumentation.
AGND AV_DD
R_DAC
V_REFOUT
V_RCAP
V_REF+
V_REF−
X_IN
X_OUT
IDAC2
IDAC1
8−Bit
IDAC
8−Bit
IDAC
1.25V or
2.5V
Reference
Clock Generator
Offset
DAC
A_IN0
A_IN1
A_IN2
A_IN3
A_IN4
A_IN5
A_IN6
A_IN7
A_INCOM
MUX
BUF
+
PGA
Digital I/O
Interface
DV_DD DGND BUFEN
D0 ... D7
2nd−Order
Modulator
Program−
mable
Digital
F ilter
Registers
Controller
RAM
4K Bytes
FLASH
WREN
Serial Interface
PDWN DSYNC RESET DRDY
POL
SCLK
D_IN
D_OUT
CS
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.
SPI is a trademark of Motorola.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2001–2005, Texas Instruments Incorporated