Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - AD converter (ADC) External SOIC 16

DS ADC

VREFP VREFN

CAP DVDD

GND

AINP

AINN

SCLK

SPEED

DRDY/DOUT

PDWN

AVDD

Internal

Oscillator

G=64

CAP

ADS1131

www.ti.com

SBAS449C –JULY 2009–REVISED OCTOBER 2013

18-Bit Analog-to-Digital Converter

for Bridge Sensors

Check for Samples: ADS1131

FEATURES

DESCRIPTION

The ADS1131 is a precision, 18-bit analog-to-digital

• Complete Front-End for Bridge Sensors

converter (ADC). With an onboard, low-noise

• Available in an SO Package

amplifier, onboard oscillator, precision 18-bit delta-

• Internal Amplifier, Gain of 64

sigma (ΔΣ) ADC, and bridge power switch, the

ADS1131 provides a complete front-end solution for

• Internal Oscillator

bridge sensor applications including weigh scales,

• Low-Side Power Switch for Bridge Sensor

strain gauges, and load cells.

• 18-Bit Noise-Free Resolution

The low-noise amplifier has a gain of 64, supporting a

• Selectable 10SPS or 80SPS Data Rates

full-scale differential input of ±39mV. The ΔΣ ADC

• Simultaneous 50Hz and 60Hz Rejection at

has 18-bit effective resolution and is comprised of a

10SPS

third-order modulator and fourth-order digital filter.

Two data rates are supported: 10SPS (with both

• External Voltage Reference up to 5V for

50Hz and 60Hz rejection) and 80SPS. The ADS1131

Ratiometric Measurements

can be put into a low-power standby mode or shut off

• Simple, Pin-Driven Control

completely in power-down mode.

• Two-Wire Serial Digital Interface

The ADS1131 is controlled by dedicated pins; there

• Supply Range: 3V to 5.3V

are no digital registers to program. Data are output

over an easily-isolated serial interface that connects

• –40°C to +85°C Temperature Range

directly to the MSP430 and other microcontrollers.

APPLICATIONS

The ADS1131 is available in an SO-16 package and

is specified from –40°C to +85°C.

• Weigh Scales

• Strain Gauges

• Load Cells

• Industrial Process Control

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.

2All 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.

Summary of content (20 pages)

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ADS1131 www.ti.com SBAS449C – JULY 2009 – REVISED OCTOBER 2013 18-Bit Analog-to-Digital Converter for Bridge Sensors Check for Samples: ADS1131 FEATURES DESCRIPTION • • • • • • • • The ADS1131 is a precision, 18-bit analog-to-digital converter (ADC).
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure.
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ADS1131 www.ti.com SBAS449C – JULY 2009 – REVISED OCTOBER 2013 ELECTRICAL CHARACTERISTICS Minimum/maximum limit specifications apply from –40°C to +85°C. Typical specifications at +25°C. All specifications at AVDD = DVDD = VREFP = +5V, and VREFN = GND, unless otherwise noted. ADS1131 PARAMETER CONDITIONS MIN TYP MAX UNIT ANALOG INPUTS Full-scale input voltage (AINP – AINN) ±0.5VREF/64 V VREF = AVDD = 5V ±39.0 mV VREF = AVDD = 3V ±23.4 mV Common-mode input range GND + 1.
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com ELECTRICAL CHARACTERISTICS (continued) Minimum/maximum limit specifications apply from –40°C to +85°C. Typical specifications at +25°C. All specifications at AVDD = DVDD = VREFP = +5V, and VREFN = GND, unless otherwise noted. ADS1131 PARAMETER CONDITIONS MIN TYP MAX UNIT POWER SUPPLY Power-supply voltage (AVDD, DVDD) Analog supply current Digital supply current Power dissipation, total 3 5.
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ADS1131 www.ti.
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com OVERVIEW The ADS1131 is a precision, 18-bit ADC that includes a low-noise PGA, internal oscillator, third-order deltasigma (ΔΣ) modulator, and fourth-order digital filter. The ADS1131 provides a complete front-end solution for bridge sensor applications such as weigh scales, strain gauges, and pressure sensors. Data can be output at 10SPS for excellent 50Hz and 60Hz rejection, or at 80SPS when higher speeds are needed.
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ADS1131 www.ti.com SBAS449C – JULY 2009 – REVISED OCTOBER 2013 VOLTAGE REFERENCE INPUTS (VREFP, VREFN) LOW-SIDE POWER SWITCH (SW) The voltage reference used by the modulator is generated from the voltage difference between VREFP and VREFN: VREF = VREFP – VREFN. The reference inputs use a structure similar to that of the analog inputs. In order to increase the reference input impedance, a switching buffer circuitry is used to reduce the input equivalent capacitance.
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com FREQUENCY RESPONSE 0 Data Rate = 10SPS 4 -50 Gain (dB) The ADS1131 uses a sinc digital filter with the frequency response. The frequency response repeats at multiples of the modulator sampling frequency of 76.8kHz. The overall response is that of a low-pass filter with a –3dB cutoff frequency of 3.32Hz with the SPEED pin tied low (10SPS data rate) and 11.64Hz with the SPEED pin tied high (80SPS data rate).
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ADS1131 www.ti.com SBAS449C – JULY 2009 – REVISED OCTOBER 2013 Table 1. Data Rate Settings SETTLING TIME Fast changes in the input signal require time to settle. For example, an external multiplexer in front of the ADS1131 can generate abrupt changes in input voltage by simply switching the multiplexer input channels. These sorts of changes in the input require four data conversion cycles to settle. When continuously converting, five readings may be necessary in order to settle the data.
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com DATA READY/DATA OUTPUT (DRDY/DOUT) DATA RETRIEVAL This digital output pin serves two purposes. First, it indicates when new data are ready by going low. Afterwards, on the first rising edge of SCLK, the DRDY/DOUT pin changes function and begins outputting the conversion data, most significant bit (MSB) first. Data are shifted out on each subsequent SCLK rising edge.
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ADS1131 www.ti.com SBAS449C – JULY 2009 – REVISED OCTOBER 2013 STANDBY MODE When tSTANDBY has passed with SCLK held high, Standby mode activates. DRDY/DOUT stays high when Standby mode begins. SCLK must remain high to stay in Standby mode. To exit Standby mode (wakeup), set SCLK low. The first data after exiting Standby mode are valid. Standby mode dramatically reduces power consumption by shutting down most of the circuitry.
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com POWER-DOWN MODE Power-Down mode shuts down the entire ADC circuitry and reduces the total power consumption close to zero. To enter Power-Down mode, simply hold the PDWN pin low. Power-Down mode also resets the entire circuitry. Power-Down mode can be initiated at any time during readback; it is not necessary to retrieve all 18 bits of data beforehand. Figure 9 shows the wake-up timing from Power-Down mode.
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ADS1131 www.ti.com SBAS449C – JULY 2009 – REVISED OCTOBER 2013 APPLICATION EXAMPLE Weigh Scale System Figure 10 shows a typical ADS1131 application as part of a weigh scale system. 2.7V to 5.3V 3V (1) 1 mF 13 AVDD 10 5 - VREFP CAP DRDY/DOUT 0.1mF 6 SCLK CAP + ADS1131 7 8 VDD DVDD (2) Load Cell (1) 1mF 1 PDWN SPEED AINP 16 15 14 4 MSP430x4xx or Other Microprocessor AINN 9 VREFN 12 SW GND GND 2, 3, 11 (1) Place a 0.
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ADS1131 SBAS449C – JULY 2009 – REVISED OCTOBER 2013 www.ti.com REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision B (September 2011) to Revision C Page • Changed pin 12 name from PSW to SW in pinout drawing ................................................................................................. 5 • Changed pin 12 name from PSW to SW in Pin Descriptions table ....................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 9-Oct-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device ADS1131IDR Package Package Pins Type Drawing SOIC D 16 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2500 330.0 16.4 Pack Materials-Page 1 6.5 B0 (mm) K0 (mm) P1 (mm) 10.3 2.1 8.0 W Pin1 (mm) Quadrant 16.
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PACKAGE MATERIALS INFORMATION www.ti.com 9-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS1131IDR SOIC D 16 2500 333.2 345.9 28.
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