Datasheet AD7898 (Analog Devices)

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5 V, 12-Bit, Serial 220 kSPS ADC in an 8-Lead Package AD7898* FEATURES FUNCTIONAL BLOCK DIAGRAM Fast 12-Bit ADC with 220 kSPS Throughput Rate REF IN V 8-Lead SOIC DD Single 5 V Supply Operation AD7898 High Speed, Flexible, Serial Interface that Allows Interfacing to 3 V Processors TRACK/HOLD On-Chip Track/Hold Amplifier SIGNAL Selection of Input Ranges VIN SCALING* 12-BIT
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10 V for AD7898-10 ADC
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2.5 V for AD7898-3 High Input Impedance OUTPUT Low Power: 22.5 mW Max CONVST REGISTER GND VDRIVE SCLK SDATA *AD7898-10, AD7898-3 GENERAL DESCRIPTION PRODUCT HIGHLIGHTS
The AD7898 is a fast 12-bit ADC that operates from a single 1. Fast, 12-Bit ADC in 8-Lead Package 5 V supply and is housed in a small 8-lead SOIC package. The The AD7898 contains a 220 kSPS ADC, a track/hold ampli- part contains a successive approximation A/D converter, an on- fier, control logic, and a high speed serial interface, all in an chip track/hold amplifier, an on-chip clock, and a high speed 8-lead package. This offers considerable space saving over serial interface. alternative solutions. The AD7898 offers two modes of operation. In Mode 0, con- 2. Low Power, Single-Supply Operation version is initiated by the CONVST input and the conversion The AD7898 operates from a single 5 V supply and con- process is controlled by an internal clock oscillator. In this mode, sumes only 22.5 mW. The VDRIVE function allows the serial the serial interface consists of three wires and the AD7898 is interface to connect directly to either 3 V or 5 V processor capable of throughput rates up to 220 kSPS. In Mode 1, the systems independent of VDD. conversion process is controlled by an externally applied SCLK 3. Flexible, High Speed Serial Interface with data being accessed from the part during conversion. In The part provides a flexible, high speed serial interface that this mode, the serial interface consists of three wires and the has two distinct modes of operation. Mode 0 provides a three- AD7898 is capable of throughput rates up to 220 kSPS. wire interface with data being accessed from the AD7898 In addition to the traditional dc accuracy specifications, such as when conversion is complete. Mode 1 offers a three-wire linearity and full-scale and offset errors, the AD7898 is specified interface with data being accessed during conversion. for dynamic performance parameters, including harmonic dis- 4. Power-Down Mode tortion and signal-to-noise ratio. The AD7898 offers a proprietary power-down capability The part accepts an analog input range of ± 10 V (AD7898-10) when operated in Mode 1, making the part ideal for portable and ± 2.5 V (AD7898-3), and operates from a single 5 V supply, or hand-held applications. consuming only 22.5 mW max. The part is available in an 8-lead Standard Small Outline Package (SOIC). *Protected by U.S. Patent No. 6,681,332 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 rights of third parties that may result from its use. No license is granted by implication or otherwise
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Document Outline FEATURES GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM PRODUCT HIGHLIGHTS SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ORDERING GUIDE PIN CONFIGURATION PIN FUNCTION DESCRIPTIONS TERMINOLOGY Signal to (Noise + Distortion) Ratio Total Harmonic Distortion Peak Harmonic or Spurious Noise Intermodulation Distortion Relative Accuracy Differential Nonlinearity Positive Full-Scale Error (AD7898-10) Positive Full-Scale Error (AD7898-3) Bipolar Zero Error (AD7898-10, AD7898-3) Negative Full-Scale Error (AD7898-10) Negative Full-Scale Error (AD7898-3) Track/Hold Acquisition Time PSR (Power Supply Rejection) PERFORMANCE CURVES Noise CONVERTER DETAILS CIRCUIT DESCRIPTION Analog Input Section Acquisition Time TYPICAL CONNECTION DIAGRAM VDRIVE Feature Track/Hold Section Reference Input SERIAL INTERFACE OPERATING MODES Mode 0 Operation Mode 1 Operation Mode Selection Power-Down Mode Power-Up Times MICROPROCESSOR/MICROCONTROLLER INTERFACE FOR MODE 0 OPERATION 8x51/L51 to AD7898 Interface 68HC11/L11 to AD7898 Interface ADSP-2103/ADSP-2105 to AD7898 Interface DSP56002/L002 to AD7898 Interface MICROPROCESSOR INTERFACING FOR MODE 1 TMS320C5x/C54x to AD7898 Interface AD7898 to ADSP-21xx Interface AD7898 to DSP56xxx Interface AD7898 to MC68HC16 Interface OUTLINE DIMENSIONS Revision History