12-Bit, 20 MSPS/40 MSPS/65 MSPS Dual A/D Converter AD9238 FUNCTIONAL BLOCK DIAGRAM FEATURES AVDD AGND Integrated dual 12-bit ADC Single 3 V supply operation (2.7 V to 3.6 V) OTR A VIN+ A 12 12 SNR = 70 dB (to Nyquist, AD9238-65) D11 A TO D0 A SHA ADC OUTPUT VIN A MUX/ SFDR = 80.5 dBc (to Nyquist, AD9238-65) OEB A BUFFERS Low power: 300 mW/channel at 65 MSPS REFT A Differential input with 500 MHz, 3 dB bandwidth MUX SELECT CLK A REFB A Exceptional crosstalk immunity > 85 dB CLOCK CLK B DUTY CYCLE Flexible analog input: 1 V p-p to 2 V p-p range VREF STABILIZER DCS Offset binary or twos complement data format SENSE SHARED REF Clock duty cycle stabilizer AGND 0.5V PWDN A MODE Output datamux option PWDN B CONTROL DFS REFT B APPLICATIONS REFB B OTR B Ultrasound equipment VIN+ B 12 12 SHA ADC OUTPUT D11 B TO D0 B Direct conversion or IF sampling receivers VIN B MUX/ BUFFERS OEB B WB-CDMA, CDMA2000, WiMAX AD9238 Battery-powered instruments Hand-held scopemeters DRVDD DRGND Low cost, digital oscilloscopes Figure 1. Fabricated on an advanced CMOS process, the AD9238 is available GENERAL DESCRIPTION in a Pb-free, space saving, 64-lead LQFP or LFCSP and is The AD9238 is a dual, 3 V, 12-bit, 20 MSPS/40 MSPS/65 MSPS specified over the industrial temperature range (40C to +85C). analog-to-digital converter (ADC). It features dual high performance sample-and-hold amplifiers (SHAs) and an PRODUCT HIGHLIGHTS integrated voltage reference. The AD9238 uses a multistage 1. Pin-compatible with the AD9248, 14-bit 20MSPS/ differential pipelined architecture with output error correction 40 MSPS/65 MSPS ADC. logic to provide 12-bit accuracy and to guarantee no missing 2. Speed grade options of 20 MSPS, 40 MSPS, and 65 MSPS codes over the full operating temperature range at up to allow flexibility between power, cost, and performance to 65 MSPS data rates. The wide bandwidth, differential SHA suit an application. allows for a variety of user-selectable input ranges and offsets, 3. Low power consumption: AD9238-65: 65 MSPS = 600 mW, including single-ended applications. It is suitable for various AD9238-40: 40 MSPS = 330 mW, and AD9238-20: 20 MSPS = applications, including multiplexed systems that switch full- 180 mW. scale voltage levels in successive channels and for sampling inputs at frequencies well beyond the Nyquist rate. 4. Typical channel isolation of 85 dB f = 10 MHz. IN 5. The clock duty cycle stabilizer (AD9238-20/AD9238-40/ Dual single-ended clock inputs are used to control all internal AD9238-65) maintains performance over a wide range of conversion cycles. A duty cycle stabilizer is available and can clock duty cycles. compensate for wide variations in the clock duty cycle, allowing the converter to maintain excellent performance. The digital 6. Multiplexed data output option enables single-port operation output data is presented in either straight binary or twos from either Data Port A or Data Port B. complement format. Out-of-range signals indicate an overflow condition, which can be used with the most significant bit to determine low or high overflow. Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.326.8703 20032010 Analog Devices, Inc. All rights reserved. 02640-001AD9238 TABLE OF CONTENTS Specifications ..................................................................................... 4 Clock Circuitry ........................................................................... 21 DC Specifications ......................................................................... 4 Analog Inputs ............................................................................. 21 AC Specifications .......................................................................... 5 Reference Circuitry .................................................................... 21 Digital Specifications ................................................................... 6 Digital Control logic .................................................................. 21 Switching Specifications .............................................................. 6 Outputs ........................................................................................ 21 Absolute Maximum Ratings ............................................................ 7 LQFP Evaluation Board Bill of Materials (BOM) .................. 23 Explanation of Test Levels ........................................................... 7 LQFP Evaluation Board Schematics ........................................ 24 ESD Caution .................................................................................. 7 LQFP PCB Layers ....................................................................... 28 Pin Configurations and Function Descriptions............................ 8 Dual ADC LFCSP PCB .................................................................. 34 Terminology .................................................................................... 10 Power Connector ........................................................................ 34 Typical Performance Characteristics ........................................... 11 Analog Inputs ............................................................................. 34 Equivalent Circuits ......................................................................... 15 Optional Operational Amplifier .............................................. 34 Theory of Operation ...................................................................... 16 Clock ............................................................................................ 34 Analog Input ............................................................................... 16 Voltage Reference ....................................................................... 34 Clock Input and Considerations .............................................. 17 Data Outputs ............................................................................... 34 Power Dissipation and Standby Mode ..................................... 18 LFCSP Evaluation Board Bill of Materials (BOM) ................ 35 Digital Outputs ........................................................................... 18 LFCSP PCB Schematics ............................................................. 36 Timing .......................................................................................... 18 LFCSP PCB Layers ..................................................................... 39 Data Format ................................................................................ 19 Thermal Considerations ............................................................ 44 Voltage Reference ....................................................................... 19 Outline Dimensions ....................................................................... 45 AD9238 LQFP Evaluation Board ................................................. 21 Ordering Guide .......................................................................... 46 REVISION HISTORY Changes to Table 2 ............................................................................ 5 11/10Rev. B to Rev. C Added Digital Specifications ........................................................... 6 Changes to Absolute Maximum Ratings Section ......................... 7 Moved Switching Specifications to ................................................ 6 Added Figure 4 Renumbered Sequentially .................................. 8 Changes to Pin Function Descriptions .......................................... 8 Changes to Analog Input Section ................................................. 16 Changes to Terminology Section ................................................. 10 Deleted Note 1 from Dual ADC LFCSP PCB Section ............... 34 Changes to Figure 29 ...................................................................... 15 Changes to Outline Dimensions ................................................... 45 Changes to Clock Input and Considerations Section ................ 17 4/05Rev. A to Rev. B Changes to Figure 33 ...................................................................... 18 Changes to Format and Layout ........................................ Universal Changes to Data Format Section .................................................. 19 Added LFCSP ..................................................................... Universal Added AD9238 LQFP Evaluation Board Section ...................... 21 Changes to Features and Applications ........................................... 1 Added Dual ADC LFCSP PCB Section ....................................... 34 Changes to General Description and Product Highlights .......... 1 Added Thermal Considerations Section ..................................... 44 Changes to Figure 1 .......................................................................... 1 Updated Outline Dimensions ....................................................... 45 Changes to Table 1 ............................................................................ 3 Changes to Ordering Guide .......................................................... 46 Rev. C Page 2 of 48