14位128kSPS采樣ADC的完整AD679

　　The AD679 is a complete， multipurpose 14-bit monolithic analog-to-digital converter， consisting of a sample-and-hold amplifier （SHA）， a microprocessor-compatible bus interface， a voltage reference， and clock generation circuitry. The AD679 is specified for ac （or dynamic） parameters such as S/N+D ratio， THD， and IMD， which are important in signal processing applications. In addition， the AD679K， B， and T grades are fully specified for dc parameters that are important in measurement applications. The 14 data bits are accessed in two read operations （8 + 6）， with left justification. Data format is straight binary for unipolar mode and twos complement binary for bipolar mode. The input has a full-scale range of 10 V with a full power bandwidth of 1 MHz and a full linear bandwidth of 500 kHz. High input impedance （10 M?） allows direct connection to unbuffered sources without signal degradation. Conversions can be initiated either under microprocessor control or by an external clock asynchronous to the system clock. This product is fabricated on Analog Devices’ BiMOS process， combining low power CMOS logic with high precision， low noise bipolar circuits; laser-trimmed thin-film resistors provide high accuracy. The converter utilizes a recursive subranging algorithm that includes error correction and flash converter circuitry to achieve high speed and resolution. The AD679 operates from +5 V and ±12 V supplies and dissipates 560 mW （typ）。 The part is available in 28-lead plastic DIP， ceramic DIP， and 44 J-leaded ceramic surface-mount packages.