Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsData collecting ICsData acquisition IC - AD converter (ADC) External , Internal SOIC 28

FEATURES

● NO MISSING CODES

● LOW POWER: 250mW

● INTERNAL REFERENCE

● WIDEBAND TRACK-AND-HOLD: 65MHz

● SINGLE +5V SUPPLY

DESCRIPTION

The ADS802 is a low-power, monolithic 12-bit, 10MHz Ana-

log-to-Digital (A/D) converter utilizing a small geometry CMOS

process. This complete converter includes a 12-bit quantizer,

wideband track-and-hold, reference, and three-state outputs.

It operates from a single +5V power supply and can be

configured to accept either differential or single-ended input

signals.

The ADS802 employs digital error correction in order to

provide excellent Nyquist differential linearity performance

for demanding imaging applications. Its low distortion, high

SNR, and high oversampling capability give it the extra

margin needed for telecommunications, test instrumentation,

and video applications.

This high-performance A/D converter is specified for AC and

DC performance at a 10MHz sampling rate. The ADS802 is

available in an SO-28 package.

12-Bit, 10MHz Sampling

ANALOG-TO-DIGITAL CONVERTER

APPLICATIONS

● IF AND BASEBAND DIGITIZATION

● DATA ACQUISITION CARDS

● TEST INSTRUMENTATION

● CCD IMAGING

Copiers

Scanners

Cameras

● VIDEO DIGITIZING

● GAMMA CAMERAS

ADS802

SBAS039B – MAY 1995 – REVISED FEBRUARY 2005

www.ti.com

Pipeline

A/D

Converter

Timing

Circuitry

Error

Correction

Logic

3-State

Outputs

T/H

12-Bit

Digital

Data

CLK

+1.25V

+3.25V

MSBI OE

REFT

REFB

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.

S802U

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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ADS802 ADS 802 U SBAS039B – MAY 1995 – REVISED FEBRUARY 2005 12-Bit, 10MHz Sampling ANALOG-TO-DIGITAL CONVERTER FEATURES DESCRIPTION ● ● ● ● ● The ADS802 is a low-power, monolithic 12-bit, 10MHz Analog-to-Digital (A/D) converter utilizing a small geometry CMOS process. This complete converter includes a 12-bit quantizer, wideband track-and-hold, reference, and three-state outputs.
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ELECTROSTATIC DISCHARGE SENSITIVITY ABSOLUTE MAXIMUM RATINGS(1) +VS ........................................................................................................ +6V Analog Input .............................................................. 0V to (+VS + 300mV) 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.
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ELECTRICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +5V, and Sampling Rate = 10MHz, and with a 50% duty cycle clock having a 2ns rise-and-fall time, unless otherwise noted. ADS802U PARAMETER CONDITIONS TEMP DYNAMIC CHARACTERISTICS (Cont.) 2-Tone Intermodulation Distortion (IMD)(3) f = 4.4MHz and 4.
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PIN DESCRIPTIONS PIN CONFIGURATION Top View SO GND 1 28 GND B1 2 27 IN B2 3 26 IN B3 4 25 GND B4 5 24 +VS B5 6 23 REFT B6 7 22 CM ADS802 PIN DESIGNATOR 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 GND B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 GND +VS CLK +VS OE 19 MSBI 20 21 +VS REFB B7 8 21 REFB B8 9 20 +VS B9 10 19 MSBI B10 11 18 OE B11 12 17 +VS B12 13 16 CLK 22 CM GND 14 15 +VS 23 REFT 24 25 26 27 28 +VS GND IN IN GND DESCRIPTION Gro
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TYPICAL CHARACTERISTICS At TA = +25°C, VS = +5V, Sampling Rate = 10MHz, and with a 50% duty cycle clock having a 2ns rise-and-fall time, unless otherwise noted. SPECTRAL PERFORMANCE SPECTRAL PERFORMANCE 0 0 fIN = 1MHz –20 –40 –40 Amplitude (dB) Amplitude (dB) fIN = 500kHz –20 –60 –80 –100 –60 –80 –100 –120 –120 0 1.0 2.0 3.0 4.0 5.0 0 1.0 2.0 Frequency (MHz) 3.0 4.0 5.0 Frequency (MHz) SPECTRAL PERFORMANCE 2-TONE INTERMODULATION 0 0 –20 –20 f1 = 4.
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TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +5V, Sampling Rate = 10MHz, and with a 50% duty cycle clock having a 2ns rise-and-fall time, unless otherwise noted. OUTPUT NOISE HISTOGRAM (NO SIGNAL) SWEPT POWER SFDR 800k 100 80 fIN = 10MHz SFDR (dBFS) Counts 600k 400k 60 40 200k 20 0.0 0 N–2 N–1 N N+1 N+2 –50 –40 –30 Code –20 SWEPT POWER SNR 0 10 INTEGRAL LINEARITY ERROR 80 4.0 fIN = 500kHz fIN = 5MHz 60 2.0 ILE (LSB) SNR (dB) –10 Input Amplitude (dBm) 40 20 0 –2.
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TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +5V, Sampling Rate = 10MHz, and with a 50% duty cycle clock having a 2ns rise-and-fall time, unless otherwise noted. DIFFERENTIAL LINEARITY ERROR vs TEMPERATURE SPURIOUS-FREE DYNAMIC RANGE (SFDR) vs TEMPERATURE 80 1.0 75 SFDR (dBFS) DLE (LSBs) 0.8 0.6 fIN = 5MHz 0.4 fIN = 500kHz 70 65 0.2 fIN = 5MHz fIN = 500kHz 60 0.
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TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +5V, Sampling Rate = 10MHz, and with a 50% duty cycle clock having a 2ns rise-and-fall time, unless otherwise noted. OFFSET ERROR vs TEMPERATURE –1.25 –0.55 –1.5 Offset (%FSR) Gain (%FSR) GAIN ERROR vs TEMPERATURE –0.05 –1.05 –1.55 –2.0 –2.
PAGE 9
THEORY OF OPERATION Op Amp Bias The ADS802 is a high-speed, sampling A/D converter with pipelining. It uses a fully differential architecture and digital error correction to ensure 12-bit resolution. The differential track-and-hold circuit is shown in Figure 1. The switches are controlled by an internal clock that has a non-overlapping 2phase signal, φ1 and φ2. At the sampling time, the input signal is sampled on the bottom plates of the input capacitors.
PAGE 10
align it with the data created from the following quantizer stages. This aligned data is fed into a digital error correction circuit that can adjust the output data based on the information found on the redundant bits. This technique gives the ADS802 excellent differential linearity and ensures no missing codes at the 12-bit level. Since there are two pipeline stages per external clock cycle, there is a 6.5 clock cycle data latency from the start convert signal to the valid output data.
PAGE 11
former-coupled input arrangement provides good high-frequency AC performance. It is important to select a transformer that gives low distortion and does not exhibit core saturation at full-scale voltage levels. Since the transformer does not appreciably load the ladder, there is no need to buffer the CommonMode (CM) output in this instance. In general, it is advisable to keep the current draw from the CM output pin below 0.5µA to avoid nonlinearity in the internal reference ladder.
PAGE 12
+5V 604Ω +5V 301Ω BAS16(1) Optional High Impedance Input Amplifier 301Ω 27 IN OPA842 301Ω 2.49kΩ 0.1µF +5V(2) 22pF 0.1µF –5V 604Ω DC-Coupled Input Signal +5V OPA842 604Ω OPA130 +5V –5V 24.9Ω ADS802 49.9Ω 2.49kΩ +2.25V 22 CM +5V 301Ω BAS16(1) 301Ω Input Level Shift Buffer 26 IN OPA842 0.1µF –5V 22pF 604Ω NOTES: (1) A Philips BAS16 diode or equivalent may be used. (2) Supply bypassing not shown. 301Ω FIGURE 6.
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+5V RP 220Ω A1 1/2 OPA2234 +5V Top Reference +2.5V to +3.25V 2kΩ 10kΩ 6.2kΩ 10kΩ REF1004 +2.5V 10kΩ(1) A2 0.1µF +1.25V 1/2 OPA2234 10kΩ Bottom Reference RP 220Ω 10kΩ(1) NOTE: (1) Use parts alternatively for adjustment capability. FIGURE 8. Optional External Reference to Set the Full-Scale Range Utilizing a Dual, Single-Supply Op Amp. ground planes can give excellent results.
PAGE 14
FIGURE 9. ADS802 Interface Schematic with AC-Coupling and External Buffers. 14 www.ti.com ADS802 SBAS039B R2 50Ω AC Input Signal Mini-circuits T T1-6-KK81 or equivalent 0.1µF R1 50Ω 22pF 0.1µF Ext Clk (1) 22pF 0.
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PACKAGE OPTION ADDENDUM www.ti.
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MECHANICAL DATA MSSO002E – JANUARY 1995 – REVISED DECEMBER 2001 DB (R-PDSO-G**) PLASTIC SMALL-OUTLINE 28 PINS SHOWN 0,38 0,22 0,65 28 0,15 M 15 0,25 0,09 8,20 7,40 5,60 5,00 Gage Plane 1 14 0,25 A 0°–ā8° 0,95 0,55 Seating Plane 2,00 MAX 0,10 0,05 MIN PINS ** 14 16 20 24 28 30 38 A MAX 6,50 6,50 7,50 8,50 10,50 10,50 12,90 A MIN 5,90 5,90 6,90 7,90 9,90 9,90 12,30 DIM 4040065 /E 12/01 NOTES: A. B. C. D. All linear dimensions are in millimeters.
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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.