Datasheet AD9238 (Analog Devices)

12-Bit, 20 MSPS/40 MSPS/65 MSPS Dual A/D Converter AD9238 FEATURES FUNCTIONAL BLOCK DIAGRAM Integrated dual 12-bit ADC AVDD AGND Single 3 V supply operation (2.7 V to 3.6 V) OTR_A SNR = 70 dB (to Nyquist, AD9238-65) VIN+_A 12 12 D11_A TO D0_A SHA ADC OUTPUT SFDR = 80.5 dBc (to Nyquist, AD9238-65) VIN–_A MUX/ OEB_A BUFFERS Low power: 300 mW/channel at 65 MSPS Differential input with 500 MHz, 3 dB bandwidth REFT_A MUX_SELECT Exceptional crosstalk immunity > 85 dB REFB_A CLK_A CLOCK Flexible analog input: 1 V p-p to 2 V p-p range CLK_B DUTY CYCLE VREF STABILIZER DCS Offset binary or twos complement data format SENSE Clock duty cycle stabilizer SHARED_REF AGND 0.5V PWDN_A Output datamux option MODE PWDN_B CONTROL DFS REFT_B APPLICATIONS REFB_B Ultrasound equipment VIN+_B OTR_B SHA 12 ADC OUTPUT 12 Direct conversion or IF sampling receivers D11_B TO D0_B VIN–_B MUX/ BUFFERS WB-CDMA, CDMA2000, WiMAX OEB_B Battery-powered instruments AD9238 Hand-held scopemeters DRVDD DRGND
02640-001
Low cost, digital oscilloscopes
Figure 1.
GENERAL DESCRIPTION
Fabricated on an advanced CMOS process, the AD9238 is available 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 (−40°C to +85°C). 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 codes over the full operating temperature range at up to 2. Speed grade options of 20 MSPS, 40 MSPS, and 65 MSPS 65 MSPS data rates. The wide bandwidth, differential SHA allow flexibility between power, cost, and performance to allows for a variety of user-selectable input ranges and offsets, suit an application. including single-ended applications. It is suitable for various 3. Low power consumption: AD9238-65: 65 MSPS = 600 mW, applications, including multiplexed systems that switch full- AD9238-40: 40 MSPS = 330 mW, and AD9238-20: 20 MSPS = scale voltage levels in successive channels and for sampling 180 mW. inputs at frequencies well beyond the Nyquist rate. 4. Typical channel isolation of 85 dB @ fIN = 10 MHz. Dual single-ended clock inputs are used to control all internal 5. The clock duty cycle stabilizer (AD9238-20/AD9238-40/ conversion cycles. A duty cycle stabilizer is available and can AD9238-65) maintains performance over a wide range of compensate for wide variations in the clock duty cycle, allowing clock duty cycles. 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.
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS DC SPECIFICATIONS AC SPECIFICATIONS DIGITAL SPECIFICATIONS SWITCHING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS EXPLANATION OF TEST LEVELS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TERMINOLOGY TYPICAL PERFORMANCE CHARACTERISTICS EQUIVALENT CIRCUITS THEORY OF OPERATION ANALOG INPUT Differential Input Configurations Single-Ended Input Configuration CLOCK INPUT AND CONSIDERATIONS POWER DISSIPATION AND STANDBY MODE DIGITAL OUTPUTS TIMING DATA FORMAT VOLTAGE REFERENCE Internal Reference Connection External Reference Operation AD9238 LQFP EVALUATION BOARD CLOCK CIRCUITRY ANALOG INPUTS REFERENCE CIRCUITRY DIGITAL CONTROL LOGIC OUTPUTS LQFP EVALUATION BOARD BILL OF MATERIALS (BOM) LQFP EVALUATION BOARD SCHEMATICS LQFP PCB LAYERS DUAL ADC LFCSP PCB POWER CONNECTOR ANALOG INPUTS OPTIONAL OPERATIONAL AMPLIFIER CLOCK VOLTAGE REFERENCE DATA OUTPUTS LFCSP EVALUATION BOARD BILL OF MATERIALS (BOM) LFCSP PCB SCHEMATICS LFCSP PCB LAYERS THERMAL CONSIDERATIONS OUTLINE DIMENSIONS ORDERING GUIDE