Datasheet AD7678 (Analog Devices)

18-Bit, 2.5 LSB INL, 100 kSPS SAR ADC AD7678 FEATURES FUNCTIONAL BLOCK DIAGRAM 18-bit resolution with no missing codes PDBUF REF REFGND DVDD DGND No pipeline delay (SAR architecture) AGND OVDD Differential input range: ±V AVDD AD7678 REF (VREF up to 5 V) SERIAL OGND Throughput: 100 kSPS REFBUFIN PORT INL: ±2.5 LSB max (±9.5 ppm of full scale) 18 IN+ SWITCHED D[17:0] Dynamic range: 103 dB typ (V CAP DAC REF = 5 V) IN– BUSY S/(N+D): 100 dB typ @ 2 kHz (VREF = 5 V) PARALLEL INTERFACE RD Parallel (18-,16-, or 8-bit bus) and serial 5 V/3 V interface CLOCK CS SPI®/QSPI™/MICROWIRE™/DSP compatible PD CONTROL LOGIC AND MODE0 On-board reference buffer CALIBRATION CIRCUITRY RESET MODE1 Single 5 V supply operation Power dissipation: 18 mW @ 100 kSPS 180 μW @ 1 kSPS CNVST
03084–0–001
48-lead LQFP or 48-lead LFCSP package
Figure 1. Functional Block Diagram
Pin-to-pin compatible upgrade of AD7674/AD7676/AD7679 APPLICATIONS Table 1. PulSAR Selection CT scanners 800– High dynamic data acquisition Type/kSPS 100–250 500–570 1000 Geophone and hydrophone sensors
Pseudo- AD7651 AD7650/AD7652 AD7653 Differential AD7660/AD7661 AD7664/AD7666 AD7667 -
replacement (low power, multichannel)
True Bipolar AD7663 AD7665 AD7671
Instrumentation
True AD7675 AD7676 AD7677
Spectrum analysis
Differential
Medical instruments
18-Bit AD7678 AD7679 AD7674 Multichannel/ AD7654
GENERAL DESCRIPTION
Simultaneous AD7655 The AD7678 is an 18-bit, 100 kSPS, charge redistribution SAR, fully differential analog-to-digital converter that operates on a
PRODUCT HIGHLIGHTS
single 5 V power supply. The part contains a high speed 18-bit sampling ADC, an internal conversion clock, an internal 1. High Resolution, Fast Throughput. reference buffer, error correction circuits, and both serial and The AD7678 is a 100 kSPS, charge redistribution, 18-bit parallel system interface ports. SAR ADC (no latency). The part is available in 48-lead LQFP or 48-lead LFCSP 2. Excellent Accuracy. packages with operation specified from –40°C to +85°C. The AD7678 has a maximum integral nonlinearity of 2.5 LSB with no missing 18-bit codes. 3. Serial or Parallel Interface. Versatile parallel (18-, 16-, or 8-bit bus) or 2-wire serial interface arrangement compatible with both 3 V and 5 V logic.
Rev. A 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 www.analog.com Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2003
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Document Outline Specifications Timing Specifications Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Definition of Specifications Integral Nonlinearity Error (INL) Differential Nonlinearity Error (DNL) Gain Error Zero Error Spurious-Free Dynamic Range (SFDR) Effective Number of Bits (ENOB) Total Harmonic Distortion (THD) Dynamic Range Signal-to-Noise Ratio (SNR) Signal-to-(Noise + Distortion) Ratio (S/[N+D]) Aperture Delay Transient Response Typical Performance Characteristics Circuit Information Converter Operation Transfer Functions Typical Connection Diagram Analog Inputs Driver Amplifier Choice Single-to-Differential Driver Voltage Reference Power Supply Power Dissipation versus Throughput Conversion Control Digital Interface Parallel Interface Serial Interface Master Serial Interface Internal Clock Slave Serial Interface External Clock External Discontinuous Clock Data Read after Conversion External Clock Data Read during Conversion Microprocessor Interfacing SPI Interface (ADSP-219x) Application Hints Layout Evaluating the AD7678’s Performance Outline Dimensions Ordering Guide