Datasheet

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

FEATURES

● +2.7V TO +3.7V SUPPLY OPERATION

● INTERNAL REFERENCE

● LOW POWER: 52mW at +3V

● SINGLE-ENDED INPUT RANGE: 1V to 2V

● WIDEBAND TRACK/HOLD: 350MHz

● SSOP-28 PACKAGE

DESCRIPTION

The ADS900 is a high-speed pipelined Analog-to-Digital

Converter (ADC). This complete converter includes a high

bandwidth track-and-hold, a 10-bit quantizer, and an inter-

nal reference.

The ADS900 employs digital error correction techniques to

provide excellent differential linearity for demanding im-

aging applications. Its low distortion and high SNR give the

extra margin needed for telecommunications, video and

test instrumentation applications.

This high-performance ADC is specified for performance

at a 20MHz sampling rate. The ADS900 is available in an

SSOP-28 package.

10-Bit, 20MHz, +3V Supply

ANALOG-TO-DIGITAL CONVERTER

APPLICATIONS

● PORTABLE INSTRUMENTATION

● IF AND BASEBAND COMMUNICATIONS

● CABLE MODEMS

● SET-TOP BOXES

● PORTABLE TEST EQUIPMENT

● COMPUTER SCANNERS

Pipeline

A/D

Internal

Reference

Timing

Circuitry

Error

Correction

3-State

Outputs

T/H

10-Bit

Digital

Data

CLK

ADS900

OEPwrdn1V

REF

LnByCMLpBy

(Opt.)

ADS900

SBAS058A – MAY 2001

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.

Summary of content (16 pages)

PAGE 1
ADS900 ADS 900 E SBAS058A – MAY 2001 10-Bit, 20MHz, +3V Supply ANALOG-TO-DIGITAL CONVERTER TM FEATURES DESCRIPTION ● ● ● ● ● ● The ADS900 is a high-speed pipelined Analog-to-Digital Converter (ADC). This complete converter includes a high bandwidth track-and-hold, a 10-bit quantizer, and an internal reference. The ADS900 employs digital error correction techniques to provide excellent differential linearity for demanding imaging applications.
PAGE 2
ABSOLUTE MAXIMUM RATINGS ELECTROSTATIC DISCHARGE SENSITIVITY +VS ....................................................................................................... +6V Analog Input ............................................................................... +VS +0.3V Logic Input ................................................................................. +VS +0.3V Case Temperature ......................................................................... +100°C Junction Temperature ...........
PAGE 3
ELECTRICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +3V, Single-Ended Input, Sampling Rate = 20MHz, unless otherwise specified. ADS900E PARAMETER DYNAMIC CHARACTERISTICS Differential Linearity Error f = 500kHz (Largest Code Error) f = 10MHz (Largest Code Error) No Missing Codes Integral Nonlinearity Error, f = 500kHz Spurious Free Dynamic Range(1) f = 500kHz (–1dBFS(2) input) f = 10MHz (–1dBFS(2) input) Two-Tone Intermodulation Distortion(3) f = 4.5MHz and 5.
PAGE 4
PIN CONFIGURATION PIN DESCRIPTIONS Top View SSOP +VS 1 28 +VS LVDD 2 27 IN LSB Bit 10 3 26 CM Bit 9 4 25 LnBy Bit 8 5 24 IN Bit 7 6 23 1VREF Bit 6 7 22 NC Bit 5 8 21 LpBy Bit 4 9 20 GND Bit 3 10 19 GND Bit 2 11 18 +VS MSB Bit 1 12 17 Pwrdn GND 13 16 OE GND 14 15 CLK ADS900 PIN DESIGNATOR 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 +VS LVDD Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 GND GND CLK OE Pwrd
PAGE 5
TYPICAL CHARACTERISTICS At TA = +25°C, VS = LVDD = +3V, Single-Ended Input, Sampling Rate = 20MHz, unless otherwise specified. SPECTRAL PERFORMANCE SPECTRAL PERFORMANCE 0 0 fIN = 500kHz fIN = 3MHz –20 Amplitude (dB) Amplitude (dB) –20 –40 –60 –80 –40 –60 –80 –100 –100 0 2 4 6 8 10 0 2 4 Frequency (MHz) SPECTRAL PERFORMANCE 10 0 fIN = 9MHz –20 f1 = 3.5MHz at –7dBFS f2 = 3.
PAGE 6
TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = LVDD = +3V, Single-Ended Input, Sampling Rate = 20MHz, unless otherwise specified. SWEPT POWER SFDR INTEGRAL LINEARITY ERROR 60 10.0 fIN = 500kHz 50 SFDR (dBFS, dBc) ILE (LSB) 5.0 0 40 dBFS 30 20 –5.0 dBc 10 0 –10.
PAGE 7
TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = LVDD = +3V, Single-Ended Input, Sampling Rate = 20MHz, unless otherwise specified. SIGNAL-TO-NOISE RATIO (SNR) vs TEMPERATURE POWER DISSIPATION vs TEMPERATURE 55 65 fIN = 10MHz fIN = 500kHz 45 40 –50 60 Power (mW) SNR (dB) 50 55 50 –25 0 25 50 75 100 –50 –25 0 Temperature (°C) GAIN ERROR vs TEMPERATURE 50 75 100 OFFSET ERROR vs TEMPERATURE 6.5 –25 6.0 –30 Offset Error (mV) Gain (%FSR) 25 Temperature (°C) 5.5 5.
PAGE 8
THEORY OF OPERATION Op Amp Bias The ADS900 is a high speed sampling ADC that utilizes a pipeline architecture. The fully differential topology and digital error correction guarantee 10-bit resolution. The track-and-hold circuit is shown in Figure 1. The switches are controlled by an internal clock which has a non-overlapping two phase signal, φ1 and φ2. At the sampling time the input signal is sampled on the bottom plates of the input capacitors.
PAGE 9
The pipelined quantizer architecture has 9 stages with each stage containing a two-bit quantizer and a two bit Digitalto-Analog Converter (DAC), as shown in Figure 2. Each two-bit quantizer stage converts on the edge of the subclock, which is the same frequency of the externally applied clock. The output of each quantizer is fed into its own delay line to time-align it with the data created from the following quantizer stages.
PAGE 10
As a passive component, a transformer can be used to stepup the signal amplitude without adding noise or distortion. At the same time it electrically isolates the front-end from the converter. In order to achieve optimum performance and to bias the converter inputs up to the correct common-mode voltage the mid-reference pin “CM” can be tied directly to the center tap of the transformer. input signal swings 1Vp-p centered around a typical common-mode voltage of +1.5V.
PAGE 11
proper op amp should include its output swing, input common-mode range, and bias current. It should be noted that any DC voltage difference between the inputs, IN and IN, will show up as an offset at the output. At the same time an offset adjustment can be accomplished. mended to meet the rated performance specifications. However, the ADS900 performance is tolerant to duty cycle variations of as much as ±10% without degradation.
PAGE 12
POWER-DOWN MODE The ADS900’s low power consumption can be reduced even further by initiating a power down mode. For this, the Power Down Pin (Pin 17) must be tied to a logic “High” reducing the current drawn from the supply by about 70%. In normal operation the power-down mode is disabled by an internal pull-down resistor (50kΩ). During power-down the digital outputs are set in 3-state. With the clock applied, the converter does not accurately process the sampled signal.
PAGE 13
PACKAGE OPTION ADDENDUM www.ti.
PAGE 14
PACKAGE MATERIALS INFORMATION www.ti.com 9-May-2008 TAPE AND REEL INFORMATION *All dimensions are nominal Device ADS900E/1K Package Package Pins Type Drawing SSOP DB 28 SPQ Reel Reel Diameter Width (mm) W1 (mm) 1000 330.0 16.4 Pack Materials-Page 1 A0 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 8.2 10.5 2.5 12.0 16.
PAGE 15
PACKAGE MATERIALS INFORMATION www.ti.com 9-May-2008 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS900E/1K SSOP DB 28 1000 346.0 346.0 33.
PAGE 16
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.