5 V, 12-Bit, Serial 220 kSPS a ADC in an 8-Lead Package * AD7898 FEATURES FUNCTIONAL BLOCK DIAGRAM Fast 12-Bit ADC with 220 kSPS Throughput Rate V REF IN DD 8-Lead SOIC 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 V IN SCALING* 12-BIT 10 V for AD7898-10 ADC 2.5 V for AD7898-3 High Input Impedance OUTPUT Low Power: 22.5 mW Max CONVST REGISTER GND VDRIVE SDATA SCLK *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 5V 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 V function allows the serial DRIVE 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 V . DD 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. may result from its use. No license is granted by implication or otherwise Tel: 781/329-4700 www.analog.com under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781/326-8703 2004 Analog Devices, Inc. All rights reserved.(V = 4.75 V to 5.25 V, V = 2.7 V to 5.25 V REF IN = 2.5 V. Specifications apply DD DRIVE 1 to both Mode 0 and Mode 1 operations T = T to T , unless otherwise noted.) AD7898SPECIFICATIONS A MIN MAX l Parameter A Version Unit Test Conditions/Comments DYNAMIC PERFORMANCE 2 Signal to (Noise + Distortion) Ratio T to T 71 dB min f = 30 kHz Sine Wave MIN MAX IN 2 Total Harmonic Distortion (THD) 78 dB max f = 30 kHz Sine Wave IN 2 Peak Harmonic or Spurious Noise 89 dB typ f = 30 kHz Sine Wave IN 2 Intermodulation Distortion (IMD) fa = 29.1 kHz, fb = 29.9 kHz 2nd Order Terms 88 dB typ 3rd Order Terms 88 dB typ Aperture Delay 20 ns typ Aperture Jitter 75 ps typ Full Power BandwidthAD7898-10 3.6 MHz typ 3 dB Full Power BandwidthAD7898-3 4.7 MHz typ 3 dB Full Power BandwidthAD7898-10 2.15 MHz typ 1 dB Full Power BandwidthAD7898-3 2.4 MHz typ 1 dB DC ACCURACY Resolution 12 Bits Minimum Resolution for Which 12 Bits No Missing Codes are Guaranteed 2 Relative Accuracy 1 LSB max 2 Differential Nonlinearity 0.9 LSB max 2 Positive Full-Scale Error 3 LSB max 2 Negative Full-Scale Error 3 LSB max Bipolar Zero Error 4 LSB max ANALOG INPUT AD7898-10 Input Voltage Range 10 Volts Input Resistance 24 k min AD7898-3 Input Voltage Range 2.5 Volts Input Resistance 5 k min REFERENCE INPUT REF IN Input Voltage Range 2.375/2.625 V min/V max 2.5 V 5% Input Current 1 A max 2, 3 Input Capacitance 10 pF max LOGIC INPUTS Input High Voltage, V V 0.7 V min INH DRIVE 4 Input Low Voltage, V V 0.3 V max INL DRIVE Input Current, I 1 A max Typically 10 nA, V = 0 V or V IN IN DRIVE 2, 3 Input Capacitance, C 10 pF max IN LOGIC OUTPUTS Output High Voltage, V V 0.4 V min I = 200 A V = 2.7 V to 5.25 V OH DRIVE SOURCE DRIVE Output Low Voltage, V 0.4 V max I = 200 A OL SINK Floating-State Leakage Current 10 A max 2, 3 Floating-State Output Capacitance 10 pF max Output Coding Twos Complement CONVERSION RATE Mode 0 Operation 220 kSPS max With V = 5 V 5% DRIVE 215 kSPS max With V = 2.7 V to 3.6 V DRIVE Mode 1 Operation 220 kSPS max POWER REQUIREMENTS V 4.75 to 5.25 V min to V max For Specified Performance DD V 2.7 to 5.25 V min to V max For Specified Performance DRIVE I Static 4.25 mA max Digital Inputs V DD DRIVE I Operational 4.5 mA max Digital Inputs V DD DRIVE Power Dissipation 22.5 mW max POWER-DOWN MODE I 25C5 A max Digital Inputs GND, V = 5 V 5% DD DD T to T 20 A max Digital Inputs GND, V = 5 V 5% MIN MAX DD Power Dissipation 25C (Operational) 25 W max V = 5 V DD NOTES 1 Temperature ranges are as follows: A Version: 40C to +85C. 2 See Terminology. 3 Sample tested 25C to ensure compliance. 4 Operational with V = 2.35 V, with Input Low Voltage, V = 0.4 V DRIVE INL Specifications subject to change without notice. 2 REV. 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