Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - AD converter (ADC) External VSSOP 8

DESCRIPTION

The ADS8324 is a 14-bit, sampling Analog-to-Digital (A/D)

converter with tested specifications using a 1.8V supply

voltage. It requires very little power, even when operating at

the full 50kHz data rate. At lower data rates, the high speed

of the device enables it to spend most of its time in the

power-down mode—the average power dissipation is less

than 1mW at 10kHz data rate.

The ADS8324 also features a synchronous serial (SPI/SSI

compatible) interface, and a differential input. The refer-

ence voltage can be set to any level within the range of

500mV to V

/2.

Ultra-low power and small size make the ADS8324 ideal

for portable and battery-operated systems. It is also a

perfect fit for remote data acquisition modules, simulta-

neous multi-channel systems, and isolated data acquisi-

tion. The ADS8324 is available in an MSOP-8 package.

14-Bit, High Speed, 1.8V MicroPower Sampling

ANALOG-TO-DIGITAL CONVERTER

FEATURES

● BIPOLAR INPUT RANGE

● 1.8V OPERATION

● 50kHz SAMPLING RATE

● MICRO POWER:

5.0mW at 2.7V

2.5mW at 1.8V

● POWER DOWN: 3

μA max

● MSOP-8 PACKAGE

● PIN-COMPATIBLE TO 12-BIT ADS7817

● SERIAL (SPI/SSI) INTERFACE

APPLICATIONS

● BATTERY OPERATED SYSTEMS

● REMOTE DATA ACQUISITION

● ISOLATED DATA ACQUISITION

● SIMULTANEOUS SAMPLING,

MULTI-CHANNEL SYSTEMS

● INDUSTRIAL CONTROLS

● ROBOTICS

● VIBRATION ANALYSIS

SAR

Serial

Interface

Comparator

ADS8324

S/H Amp

DCLOCK

OUT

CS/SHDN

+In

REF

–In

CDAC

SBAS172A – AUGUST 2001 – REVISED MARCH 2004

ADS8324

www.ti.com

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

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.

All trademarks are the property of their respective owners.

Summary of content (19 pages)

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ADS8324 SBAS172A – AUGUST 2001 – REVISED MARCH 2004 14-Bit, High Speed, 1.8V MicroPower Sampling ANALOG-TO-DIGITAL CONVERTER FEATURES DESCRIPTION ● ● ● ● The ADS8324 is a 14-bit, sampling Analog-to-Digital (A/D) converter with tested specifications using a 1.8V supply voltage. It requires very little power, even when operating at the full 50kHz data rate.
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ABSOLUTE MAXIMUM RATINGS(1) PIN CONFIGURATION VCC ....................................................................................................... +6V Analog Input ............................................................. –0.3V to (VCC + 0.3V) Logic Input .............................................................................. –0.3V to 6V Case Temperature ......................................................................... +100°C Junction Temperature .................................
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ELECTRICAL CHARACTERISTICS: +VCC = +1.8V At –40°C to +85°C, VREF = 0.9V, –In = 0.9V, fSAMPLE = 50kHz, and fCLK = 24 • fSAMPLE, unless otherwise specified. ADS8324E PARAMETER CONDITIONS MIN TYP RESOLUTION ANALOG INPUT Full-Scale Input Span Absolute Input Range +In – (–In) +In –In –VREF –0.1 0.8 REFERENCE INPUT Voltage Range Resistance Power Dissipation Power Down ✻ ✻ ✻ at DCC +1.8V < VCC < +3.6V ±3 ±8 ±2 ✻ ✻ ✻ ✻ ✻ ✻ ±8 50 1.8 ✻ 1.3 –0.3 1.4 80 3 ✻ ✻ ✻ ✻ ✻ ✻ ✻ 1.8 1400 250 2.5 0.
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TYPICAL CHARACTERISTICS At TA = +25°C, VCC = 1.8V, VREF = 0.9V, fSAMPLE = 50kHz, fCLK = 24 • fSAMPLE, unless otherwise specified. FREQUENCY SPECTRUM (4096 point FFT, fIN = 0.989kHz, –0.2dB) –20 –20 –40 –40 –60 –80 –60 –80 –100 –100 –120 –120 –140 –140 0 0 5 10 15 20 25 0 5 10 FREQUENCY SPECTRUM (4096 point FFT, fIN = 20.001kHz, –0.
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TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VCC = 1.8V, VREF = 0.9V, fSAMPLE = 50kHz, fCLK = 24 • fSAMPLE, unless otherwise specified. DIFFERENTIAL LINEARITY ERROR vs CODE INTEGRAL LINEARITY ERROR vs CODE 2 2 ILE (LSBs) DLE (LSBs) 1 1 0 0 –1 –1 2000H 3000H 0000H 1000H –2 2000H 1FFFH 3000H Output Code QUIESCENT CURRENT vs VCC 1FFFH REFERENCE CURRENT vs TEMPERATURE 2 1.5 1 0.5 0 1.5 2 2.5 3 3.5 9 8 7 6 5 4 3 2 1 0 –50 4 –30 –10 VCC (V) 1.8 9 1.
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TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VCC = 1.8V, VREF = 0.9V, fSAMPLE = 50kHz, fCLK = 24 • fSAMPLE, unless otherwise specified. CHANGE IN GAIN vs TEMPERATURE 1 0.8 0.8 Change from +25°C (LSB) Change from +25°C (LSB) CHANGE IN BIPOLAR OFFSET vs TEMPERATURE 1 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.
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THEORY OF OPERATION 2 • VREF peak-to-peak Single-Ended Input VREF peak-to-peak Common Voltage ADS8324 VREF peak-to-peak Differential Input FIGURE 1. Methods of Driving the ADS8324—Single-Ended or Differential. 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 –1 VCC = 1.8V Single-Ended Input 0.5 0.6 0.7 0.8 0.9 1 VREF (V) The analog input is bipolar and fully differential.
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different settling times. This may result in offset error, gain error, and linearity error that changes with both temperature and input voltage. If the impedance cannot be matched, the errors can be lessened by giving the ADS8324 additional acquisition time. The input current on the analog inputs depends on a number of factors: sample rate, input voltage, and source impedance. Essentially, the current into the ADS8324 charges the internal capacitor array during the sample period.
PAGE 9
DIGITAL INTERFACE SYMBOL SIGNAL LEVELS The CMOS digital output (DOUT) will swing from 0V to VCC. If VCC is 3V, and this output is connected to a 5V CMOS logic input, then that IC may require more supply current than normal and may have a slightly longer propagation delay. DESCRIPTION MIN tSMPL Analog Input Sample Time 4.5 TYP MAX UNITS 5.
PAGE 10
POWER DISSIPATION The architecture of the converter, the semiconductor fabrication process, and a careful design allow the ADS8324 to convert at up to a 50kHz rate while requiring very little power. Still, for the absolute lowest power dissipation, there are several things to keep in mind. The power dissipation of the ADS8324 scales directly with the conversion rate.
PAGE 11
10000 TA = 25°C VCC = 1.8V VREF = 0.9V fCLK = 24 • fSAMPLE 1000 800 Supply Current (μA) Figure 7 shows the current consumption of the ADS8324 versus sample rate. For this graph, the converter is clocked at 1.2MHz regardless of the sample rate—CS is HIGH for the remaining sample period. Figure 8 also shows current consumption versus sample rate. However, in this case, the DCLOCK period is 1/24th of the sample period—CS is HIGH for one DCLOCK cycle out of every 16.
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amp can drive the bypass capacitor without oscillation (the series resistor can help in this case). Keep in mind that while the ADS8324 draws very little current from the reference on average, there are still instantaneous current demands placed on the external input and reference circuitry. Texas Instruments OPA627 op amp provides optimum performance for buffering both the signal and reference inputs.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com (3) 11-Apr-2013 MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Top-Side Marking for that device.
PAGE 15
PACKAGE MATERIALS INFORMATION www.ti.com 16-Aug-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant ADS8324E/250 VSSOP DGK 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 ADS8324E/2K5 VSSOP DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 ADS8324EB/250 VSSOP DGK 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 16-Aug-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS8324E/250 VSSOP DGK 8 250 210.0 185.0 35.0 ADS8324E/2K5 VSSOP DGK 8 2500 367.0 367.0 35.0 ADS8324EB/250 VSSOP DGK 8 250 210.0 185.0 35.0 ADS8324EB/2K5 VSSOP DGK 8 2500 367.0 367.0 35.
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