12-Bit, 20/40/65 MSPS 3 V A/D Converter Data Sheet AD9235 FEATURES FUNCTIONAL BLOCK DIAGRAM AVDD DRVDD Single 3 V supply operation (2.7 V to 3.6 V) SNR = 70 dBc to Nyquist at 65 MSPS VIN+ 8-STAGE SFDR = 85 dBc to Nyquist at 65 MSPS SHA MDAC1 1 1/2-BIT A/D VIN PIPELINE Low power: 300 mW at 65 MSPS 4 16 3 Differential input with 500 MHz bandwidth REFT A/D On-chip reference and SHA REFB DNL = 0.4 LSB CORRECTION LOGIC Flexible analog input: 1 V p-p to 2 V p-p range 12 OUTPUT BUFFERS OTR Offset binary or twos complement data format D11 Clock duty cycle stabilizer AD9235 VREF D0 CLOCK APPLICATIONS DUTY CYCLE MODE SENSE STABILIZER SELECT Ultrasound equipment REF IF sampling in communications receivers 0.5V SELECT IS-95, CDMA-One, IMT-2000 AGND CLK PDWN MODE DGND Battery-powered instruments Hand-held scopemeters Figure 1. Low cost digital oscilloscopes GENERAL DESCRIPTION can be used with the most significant bit to determine low or The AD9235 is a family of monolithic, single 3 V supply, 12-bit, high overflow. 20/40/65 MSPS analog-to-digital converters (ADCs). This family features a high performance sample-and-hold amplifier Fabricated on an advanced CMOS process, the AD9235 is avail- (SHA) and voltage reference. The AD9235 uses a multistage able in a 28-lead TSSOP and a 32-lead LFCSP and is specified differential pipelined architecture with output error correction over the industrial temperature range (40C to +85C). logic to provide 12-bit accuracy at 20/40/65 MSPS data rates and guarantee no missing codes over the full operating PRODUCT HIGHLIGHTS temperature range. 1. The AD9235 operates from a single 3 V power supply and features a separate digital output driver supply to accommo- The wide bandwidth, truly differential SHA allows a variety of date 2.5 V and 3.3 V logic families. user-selectable input ranges and offsets including single-ended 2. Operating at 65 MSPS, the AD9235 consumes a low 300 mW. applications. It is suitable for multiplexed systems that switch 3. The patented SHA input maintains excellent performance for full-scale voltage levels in successive channels and for sampling input frequencies up to 100 MHz and can be configured for single-channel inputs at frequencies well beyond the Nyquist rate. single-ended or differential operation. Combined with power and cost savings over previously available 4. The AD9235 pinout is similar to the AD9214-65, a 10-bit, ADCs, the AD9235 is suitable for applications in communica- 65 MSPS ADC. This allows a simplified upgrade path from tions, imaging, and medical ultrasound. 10 bits to 12 bits for 65 MSPS systems. 5. The clock DCS maintains overall ADC performance over a A single-ended clock input is used to control all internal wide range of clock pulse widths. conversion cycles. A duty cycle stabilizer (DCS) compensates 6. The OTR output bit indicates when the signal is beyond the for wide variations in the clock duty cycle while maintaining selected input range. excellent overall ADC performance. The digital output data is presented in straight binary or twos complement formats. An out-of-range (OTR) signal indicates an overflow condition that Rev. D Information furnished by Analog Devices is believed to be accurate and reliable. However, no re- sponsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. 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All rights reserved. 02461-001AD9235 Data Sheet TABLE OF CONTENTS Specifications ..................................................................................... 3 Applying the AD9235 .................................................................... 15 DC Specifications ......................................................................... 3 Theory of Operation .................................................................. 15 Digital Specifications ................................................................... 4 Analog Input ............................................................................... 15 Switching Specifications .............................................................. 4 Clock Input Considerations ...................................................... 16 AC Specifications .......................................................................... 5 Power Dissipation and Standby Mode .................................... 17 Absolute Maximum Ratings ............................................................ 7 Digital Outputs ........................................................................... 18 Explanation of Test Levels ........................................................... 7 Voltage Reference ....................................................................... 18 ESD Caution .................................................................................. 7 Operational Mode Selection ..................................................... 19 Pin Configurations and Function Descriptions ........................... 8 TSSOP Evaluation Board .......................................................... 19 Definitions of Specifications ........................................................... 9 LFCSP Evaluation Board ........................................................... 20 Equivalent Circuits ......................................................................... 10 Outline Dimensions ....................................................................... 36 Typical Performance Characteristics ........................................... 11 Ordering Guide .......................................................................... 37 REVISION HISTORY Changes to TPCs 1 to 12 .................................................................. 9 10/12Rev. C to Rev. D Changes to Theory of Operation Section..................................... 13 Changes to Figure 4 and Table 6 ................................................................ 8 Changes to Analog Input Section .................................................. 13 Updated Outline Dimensions (Changed CP-32-2 to CP-32-7) ..... 36 Changes to Single-ended Input Configuration Section ............. 14 Changes to Ordering Guide .......................................................... 37 Replaced Figure 8 ............................................................................ 14 10/04Data Sheet changed from Rev. B to Rev. C Changes to Clock Input Considerations Section ........................ 14 Changes to Format ............................................................. Universal Changes to Table I ........................................................................... 15 Changes to Specifications ................................................................. 3 Changes to Power Dissipation and Standby Mode Section ....... 15 Changes to the Ordering Guide .................................................... 37 Changes to Digital Outputs Section .............................................. 15 Changes to Timing Section ............................................................ 15 5/03Data Sheet changed from Rev. A to Rev. B Changes to Figure 13 ....................................................................... 16 Added CP-32 Package (LFCSP) ........................................ Universal Changes to Figures 16 to 26 ........................................................... 17 Changes to Several Pin Names.......................................... Universal Added LFCSP Evaluation Board Section ..................................... 17 Changes to Features ........................................................................... 1 Inserted Figures 27 to 35 ................................................................ 25 Changes to Product Description ..................................................... 1 Added Table III ................................................................................ 30 Changes to Product Highlights ........................................................ 1 Updated Outline Dimensions ........................................................ 31 Changes to Specifications ................................................................. 2 Replaced Figure 1 .............................................................................. 3 8/02Data Sheet changed from Rev. 0 to Rev. A Changes to Absolute Maximum Ratings ........................................ 5 Updated RU-28 Package ................................................................ 24 Changes to Ordering Guide ............................................................. 5 Changes to Pin Function Descriptions ........................................... 6 New Definitions of Specifications Section ..................................... 7 Rev. D Page 2 of 40