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ADS7822

FEATURES

DESCRIPTION

APPLICATIONS

SAR

Control

Serial

Interface

OUT

Comparator

S/HAmp

CS/SHDN

DCLOCK

+In

REF

-In

CDAC

ADS7822

SBAS062C – JANUARY 1996 – REVISED AUGUST 2007

12-Bit, 200kHz, microPower Sampling

ANALOG-TO-DIGITAL CONVERTER

• 200kHz Sampling Rate

• microPower:

The ADS7822 is a 12-bit sampling analog-to-digital

(A/D) converter with ensured specifications over a

1.6mW at 200kHz

2.7V to 5.25V supply range. It requires very little

0.54mW at 75kHz

power even when operating at the full 200kHz rate. At

0.06mW at 7.5kHz

lower conversion rates, the high speed of the device

• Power Down: 3 μ A max

enables it to spend most of its time in the

• Mini-DIP-8, SO-8, and MSOP-8 Packages

power-down mode — the power dissipation is less

than 60 μ W at 7.5kHz.

• Pseudo-Differential Input

• Serial Interface

The ADS7822 also features operation from 2.0V to

5V, a synchronous serial interface, and a

pseudo-differential input. The reference voltage can

be set to any level within the range of 50mV to V

• Battery-Operated Systems

Ultra low power and small size make the ADS7822

• Remote Data Acquisition

ideal for battery-operated systems. It is also a perfect

• Isolated Data Acquisition

fit for remote data-acquisition modules, simultaneous

• Simultaneous Sampling, Multichannel Systems

multichannel systems, and isolated data acquisition.

The ADS7822 is available in a plastic mini-DIP-8, an

SO-8, or an MSOP-8 package.

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.

2 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.

Summary of content (28 pages)

PAGE 1
ADS7822 AD S78 22 AD S 7822 SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 12-Bit, 200kHz, microPower Sampling ANALOG-TO-DIGITAL CONVERTER FEATURES 1 DESCRIPTION • 200kHz Sampling Rate • microPower: 1.6mW at 200kHz 0.54mW at 75kHz 0.06mW at 7.5kHz • Power Down: 3μA max • Mini-DIP-8, SO-8, and MSOP-8 Packages • Pseudo-Differential Input • Serial Interface 2 The ADS7822 is a 12-bit sampling analog-to-digital (A/D) converter with ensured specifications over a 2.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 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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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 ELECTRICAL CHARACTERISTICS: +VCC = +2.7V At –40°C to +85°C, +VCC = +2.7V, VREF = +2.5V, fSAMPLE = 75kHz, and fCLK = 16 × fSAMPLE, unless otherwise noted. ADS7822 PARAMETER ADS7822B ADS7822C TEST CONDITIONS UNIT MIN TYP MAX MIN TYP MAX MIN TYP MAX ANALOG INPUT Full-scale input span +In – (–In) 0 VREF 0 VREF 0 VREF V +In – GND –0.2 VCC + 0.2 –0.2 VCC + 0.2 –0.2 VCC + 0.2 V –In – GND –0.2 +1.0 –0.2 +1.0 –0.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 ELECTRICAL CHARACTERISTICS: +VCC = +5V At –40°C to +85°C, +VCC = +5V, VREF = +5V, fSAMPLE = 200kHz, and fCLK = 16 × fSAMPLE, unless otherwise noted. ADS7822 PARAMETER ADS7822B TEST CONDITIONS UNIT MIN TYP MAX MIN TYP MAX ANALOG INPUT Full-scale input span +In – (–In) 0 VREF 0 VREF V +In – GND –0.2 VCC + 0.2 –0.2 VCC + 0.2 V –In – GND –0.2 +1.0 –0.2 +1.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 PIN CONFIGURATION D, DGK, OR P PACKAGE SO, MSOP, or DIP (TOP VIEW) VREF 1 +In 2 8 +VCC 7 DCLOCK ADS7822 -In 3 6 DOUT GND 4 5 CS/SHDN PIN ASSIGNMENTS PIN NAME DESCRIPTION NO. VREF 1 Reference input +In 2 Noninverting input –In 3 Inverting input. Connect to ground or to remote ground sense point. GND 4 Ground CS/SHDN 5 Chip select when low; Shutdown mode when high.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 TYPICAL CHARACTERISTICS At TA = +25°C, VCC = +2.7V, VREF = +2.5V, fSAMPLE = 75kHz, fCLK = 16 × fSAMPLE, unless otherwise specified. DIFFERENTIAL LINEARITY ERROR vs CODE 1.00 1.00 0.75 0.75 Differential Linearity Error (LSB) Integral Linearity Error (LSB) INTEGRAL LINEARITY ERROR vs CODE 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00 0 2048 4095 0 2048 4095 Code Figure 1. Figure 2.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VCC = +2.7V, VREF = +2.5V, fSAMPLE = 75kHz, fCLK = 16 × fSAMPLE, unless otherwise specified. CHANGE IN OFFSET vs REFERENCE VOLTAGE CHANGE IN OFFSET vs TEMPERATURE 1.2 0.6 VCC = 5V 0.4 0.8 Delta from 25°C (LSB) Change in Offset (LSB) 1.0 0.6 0.4 0.2 0.0 -0.2 -0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VCC = +2.7V, VREF = +2.5V, fSAMPLE = 75kHz, fCLK = 16 × fSAMPLE, unless otherwise specified.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VCC = +2.7V, VREF = +2.5V, fSAMPLE = 75kHz, fCLK = 16 × fSAMPLE, unless otherwise specified. POWER-SUPPLY REJECTION vs RIPPLE FREQUENCY 0 -10 -20 POWER-SUPPLY REJECTION vs RIPPLE FREQUENCY 0 VCC = 2.7V Ripple = 500mVPP VIN = 1.25VDC VREF = 2.5V -10 -20 -30 PSR (dB) PSR (dB) -30 VCC = 5V Ripple = 500mVPP VIN = 2.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 THEORY OF OPERATION The ADS7822 is a classic successive approximation register (SAR) A/D converter. The architecture is based on capacitive redistribution that inherently includes a sample/hold function. The converter is fabricated on a 0.6μ CMOS process. The architecture and process allow the ADS7822 to acquire and convert an analog signal at up to 200,000 conversions per second while consuming very little power.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 DIGITAL INTERFACE The noise inherent in the converter will also appear to increase with lower LSB size. With a 2.5V reference, the internal noise of the converter typically contributes only 0.32 LSB peak-to-peak of potential error to the output code. When the external reference is 50mV, the potential error contribution from the internal noise will be 50 times larger—16 LSBs.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 Table 1. Timing Specifications (–40°C to +85°C) SYMBOL VCC = 2.7V DESCRIPTION MIN TYP 1.5 VCC = 5V MAX MIN 2.0 1.5 TYP MAX 2.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 A falling CS signal initiates the conversion and data transfer. The first 1.5 to 2.0 clock periods of the conversion cycle are used to sample the input signal. After the second falling DCLOCK edge, DOUT is enabled and outputs a low value for one clock period. For the next 12 DCLOCK periods, DOUT outputs the conversion result, most significant bit first.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 There is an important distinction between the power-down mode that is entered after a conversion is complete and the full power-down mode that is enabled when CS is high. While both shutdown the analog section, the digital section is completely shutdown only when CS is high.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 LAYOUT For optimum performance, care should be taken with the physical layout of the ADS7822 circuitry. This is particularly true if the reference voltage is low and/or the conversion rate is high. At a 75kHz conversion rate, the ADS7822 makes a bit decision every 830ns. If the supply range is limited to 4.75V to 5.25V, then up to a 200kHz conversion rate can be used, which reduces the bit decision time to 312ns.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 +3V +3V +3V R8 26kW D1 R1 150kW R9 1kW OPA237 C2 0.1mF R3 500kW R6 1MW R2 59kW TC1 0.4V R7 5W 0.3V U2 C1 10mF VREF Mux 0.2V DCLOCK C3 0.1mF TC2 ADS7822 DOUT A0 CS/SHDN A1 Thermocouple TC3 R4 1kW C4 10mF ISO Thermal Block R10 1kW U1 R5 500W U3 C5 0.1mF R11 1kW 0.1V R12 1kW P 3-Wire Interface U4 Figure 27. Thermocouple Application Using a Mux to Scale the Input Range of the ADS7822 +2.7V to +3.
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ADS7822 www.ti.com SBAS062C – JANUARY 1996 – REVISED AUGUST 2007 Revision History Changes from Revision B (May 2006) to Revision C ...................................................................................................... Page • • • • • • • • • • Added – GND to absolute input range test conditions .......................................................................................................... Added – GND to absolute input range test conditions .......................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 6-Jul-2013 NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 6-Nov-2013 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 ADS7822E/250 VSSOP DGK 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 ADS7822E/2K5 VSSOP DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 ADS7822EB/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 6-Nov-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS7822E/250 VSSOP DGK 8 250 210.0 185.0 35.0 ADS7822E/2K5 VSSOP DGK 8 2500 367.0 367.0 35.0 ADS7822EB/250 VSSOP DGK 8 250 210.0 185.0 35.0 ADS7822EB/2K5 VSSOP DGK 8 2500 367.0 367.0 35.0 ADS7822EC/250 VSSOP DGK 8 250 210.0 185.0 35.0 ADS7822EC/2K5 VSSOP DGK 8 2500 367.0 367.0 35.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.