Datasheet

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

Pipeline

A/D

Reference

Ladder

Timing

Circuitry

Error

Correction

Logic

3-State

Outputs

T/H

8-Bit

Digital

Data

CLK

ADS931

OEPwrdn

REFBCMREFT

FEATURES

● +2.7V TO +5.5V SUPPLY OPERATION

● LOW POWER: 69mW at +3V

● ADJUSTABLE FULL SCALE RANGE WITH

EXTERNAL REFERENCE

● NO MISSING CODES

● POWER DOWN

● SSOP-28 PACKAGE

DESCRIPTION

The ADS931 is a high-speed pipelined Analog-to-Digital

(A/D) converter that is specified to operate from standard

+5V or +3V power supplies. This converter includes a high

bandwidth track/hold and an 8-bit quantizer. The perfor-

mance is specified with a single-ended input range of 1V to

2V when operating off of a +3V supply. This device also

allows for standard input ranges such as 2V to 4V or 2V to

3V, when operating on +5V supplies. The full scale input

range is set by an external reference.

The ADS931 employs digital error correction techniques to

provide excellent differential linearity for demanding imag-

ing applications. Its low distortion and high SNR give the

extra margin needed for telecommunications, video and test

instrumentation applications. The ADS931 is available in an

SSOP-28 package.

8-Bit, 33MHz Sampling

ANALOG-TO-DIGITAL CONVERTER

APPLICATIONS

● BATTERY POWERED EQUIPMENT

● CAMCORDERS

● PORTABLE TEST EQUIPMENT

● DIGITAL CAMERAS

● COMMUNICATIONS

ADS931E

ADS931

SBAS060A – 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
ADS931 ADS 931 E SBAS060A – MAY 2001 8-Bit, 33MHz Sampling ANALOG-TO-DIGITAL CONVERTER TM FEATURES DESCRIPTION ● +2.7V TO +5.5V SUPPLY OPERATION ● LOW POWER: 69mW at +3V ● ADJUSTABLE FULL SCALE RANGE WITH EXTERNAL REFERENCE ● NO MISSING CODES ● POWER DOWN ● SSOP-28 PACKAGE The ADS931 is a high-speed pipelined Analog-to-Digital (A/D) converter that is specified to operate from standard +5V or +3V power supplies. This converter includes a high bandwidth track/hold and an 8-bit quantizer.
PAGE 2
ABSOLUTE MAXIMUM RATINGS ELECTROSTATIC DISCHARGE SENSITIVITY +VS ....................................................................................................... +6V Analog Input ........................................................... (–0.3V) to (+VS +0.3V) Logic Input ............................................................. (–0.3V) to (+VS +0.3V) Case Temperature ......................................................................... +100°C Junction Temperature .........................
PAGE 3
ELECTRICAL CHARACTERISTICS (Cont.) At TA = full specified temperature range unless otherwise noted. +VS = LVDD = +3V, specified single-ended input (1V to 2V) and sampling rate = 30MHz, unless otherwise specified. The input range is 2.25V to 3.25V when specified for +5V operation.
PAGE 4
PIN CONFIGURATION PIN DESCRIPTIONS Top View SSOP +VS 1 28 +VS LVDD 2 27 IN NC 3 26 CM NC 4 25 LnBy Bit 8 (LSB) 5 24 REFB Bit 7 6 23 NC Bit 6 7 22 REFT ADS931 Bit 5 8 21 LpBy Bit 4 9 20 GND Bit 3 10 19 GND Bit 2 11 18 +VS Bit 1 (MSB) 12 17 Pwrdn GND 13 16 OE GND 14 15 CLK 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 NC NC Bit 8 (LSB) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 (MSB) GND GND CLK
PAGE 5
TYPICAL CHARACTERISTICS At TA = +25°C, VS = +3V, specified single-ended input (–1dBFS) and sampling rate = 30MHz, unless otherwise specified. SPECTRAL PERFORMANCE SPECTRAL PERFORMANCE 0 0 fIN = 500kHz fIN = 3.58MHz –20 Amplitude (dB) Amplitude (dB) –20 –40 –60 –40 –60 –80 –80 –100 –100 0 5 10 0 15 5 SPECTRAL PERFORMANCE 0 fIN = 12.5MHz fIN = 12.5MHz VS = +5V REFT = +3.25V REFB = +2.
PAGE 6
TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +3V, specified single-ended input (–1dBFS) and sampling rate = 30MHz, unless otherwise specified. DIFFERENTIAL LINEARITY ERROR DIFFERENTIAL LINEARITY ERROR 2.0 2.0 fIN = 500kHz fIN = 12.5MHz 1.0 DLE (LSB) DLE (LSB) 1.0 0 0 –1.0 –1.0 –2.0 –2.0 0 64 128 192 0 256 64 128 192 256 Output Code Output Code INTEGRAL LINEARITY ERROR SWEPT POWER SFDR 4.0 100 fIN = 500kHz dBFS 80 SFDR (dBFS, dBc) ILE (LSB) 2.0 0 –2.
PAGE 7
TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VS = +3V, specified single-ended input (–1dBFS) and sampling rate = 30MHz, unless otherwise specified. SPURIOUS FREE DYNAMIC RANGE (SFDR) vs TEMPERATURE SIGNAL-TO-NOISE RATIO vs TEMPERATURE 54 50 fIN = 12.5MHz 52 48 fIN = 500kHz 50 SNR (dB) SFDR (dBFS) fIN = 12.5MHz 48 fIN = 500kHz 46 46 44 –50 –25 0 25 50 75 44 –50 100 –25 0 50 75 100 75 100 GAIN ERROR vs TEMPERATURE POWER DISSIPATION vs TEMPERATURE 66 2.6 64 2.
PAGE 8
THEORY OF OPERATION Op Amp Bias The ADS931 is a high-speed sampling A/D converter that utilizes a pipeline architecture. The fully differential topology and digital error correction guarantee 8-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 7 stages with each stage containing a two-bit quantizer and a two bit digitalto-analog converter, as shown in Figure 2. Each two-bit quantizer stage converts on the edge of the sub-clock, 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 subsequent quantizer stages.
PAGE 10
Again, the input coupling capacitor C1 and resistor R1 form a high-pass filter. At the same time, the input impedance is defined by R1. Although many high-speed op amps operate on single supply voltages down to +3V, their ac-performance is often lower when compared to their +5V acperformance. This is especially true at signal frequencies of 5MHz or higher, where noticeable degradation is exhibited that will limit the performance of the system.
PAGE 11
+3V 10µF 0.1µF RT 4kΩ REFT +VS 0.1µF 1kΩ 0.1µF LpBy VIN IN 0.1µF 1kΩ 2kΩ ADS931 +1.5V CM 0.1µF 1kΩ LnBy +VS 3V 5V 5V 5V RT 4kΩ 12kΩ 8kΩ 3kΩ RB 4kΩ 12kΩ 8kΩ 3kΩ 0.1µF REFT REFB 2V 2V 3V 3.5V 1kΩ REFB 1V 1V 2V 1.5V 0.1µF RB 4kΩ FIGURE 6. Low-cost Solution to Supply External Reference Voltages. +VS 10Ω 1/2 A1 +VS Top Reference RF1 10kΩ RG1 REF1004 +1.2V 5kΩ 3kΩ 10Ω 1/2 A1 Bottom Reference RF2 RG2 FIGURE 7. High Accuracy Solution to Supply External Reference Voltages.
PAGE 12
duty cycle, along with fast rise and fall times (2ns or less), are recommended to meet the rated performance specifications. However, the ADS931 performance is tolerant to duty cycle variations of as much as ±10%, which should not affect the performance. For applications operating with input frequencies up to Nyquist (fCLK/2) or undersampling applications, special consideration must be made to provide a clock with very low jitter.
PAGE 13
PACKAGE OPTION ADDENDUM www.ti.
PAGE 14
PACKAGE MATERIALS INFORMATION www.ti.com 11-Mar-2008 TAPE AND REEL INFORMATION *All dimensions are nominal Device ADS931E/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 11-Mar-2008 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) ADS931E/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.