Datasheet AD7863 (Analog Devices)

Simultaneous Sampling Dual 175 kSPS 14-Bit ADC AD7863 FEATURES FUNCTIONAL BLOCK DIAGRAM Two fast 14-bit ADCs V V REF DD Four input channels 2kΩ 2.5V Simultaneous sampling and conversion REFERENCE 5.2 μs conversion time AD7863 Single supply operation Selection of input ranges SIGNAL TRACK/ VA1 ±10 V for AD7863-10 SCALING HOLD MUX 14-BIT ADC ±2.5 V for AD7863-3 V SIGNAL B1 SCALING DB0 0 V to 2.5 V for AD7863-2 OUTPUT SIGNAL TRACK/ LATCH High speed parallel interface DB13 VA2 SCALING HOLD 14-BIT Low power, 70 mW typical MUX ADC SIGNAL V CS Power saving mode, 105 μW maximum B2 SCALING RD Overvoltage protection on analog inputs CONVERSION 14-bit lead compatible upgrade to AD7862 CONTROL LOGIC CLOCK
01 0
GENERAL DESCRIPTION
1-
A0 BUSY CONVST AGND AGND DGND
41 06 The AD7863 is a high speed, low power, dual 14-bit analog-to- Figure 1. digital converter that operates from a single 5 V supply. The part contains two 5.2 μs successive approximation ADCs, two process that combines precision bipolar circuits with low power track/hold amplifiers, an internal 2.5 V reference and a high speed CMOS logic. It is available in 28-lead SOIC_W and SSOP. parallel interface. Four analog inputs are grouped into two channels
PRODUCT HIGHLIGHTS
(A and B) selected by the A0 input. Each channel has two inputs 1. The AD7863 features two complete ADC functions (VA1 and VA2 or VB1 and VB2) that can be sampled and converted simultaneously, thus preserving the relative phase information of allowing simultaneous sampling and conversion of two channels. Each ADC has a two-channel input mux. The the signals on both analog inputs. The part accepts an analog input conversion result for both channels is available 5.2 μs after range of ±10 V (AD7863-10), ±2.5 V (AD7863-3), and 0 V to initiating conversion. 2.5 V (AD7863-2). Overvoltage protection on the analog inputs for the part allows the input voltage to go to ±17 V, ±7 V, or +7 V 2. The AD7863 operates from a single 5 V supply and respectively, without causing damage. consumes 70 mW typical. The automatic power-down mode, where the part goes into power-down once A single conversion start signal (CONVST) simultaneously places conversion is complete and wakes up before the next both track/holds into hold and initiates conversion on both conversion cycle, makes the AD7863 ideal for battery- channels. The BUSY signal indicates the end of conversion and at powered or portable applications. this time the conversion results for both channels are available to be 3. The part offers a high speed parallel interface for easy read. The first read after a conversion accesses the result from V connection to microprocessors, microcontrollers, and A1 or V digital signal processors. B1, and the second read accesses the result from VA2 or VB2, depending on whether the multiplexer select (A0) is low or high, 4. The part is offered in three versions with different analog respectively. Data is read from the part via a 14-bit parallel data bus input ranges. The AD7863-10 offers the standard industrial with standard CS and RD signals. In addition to the traditional dc input range of ±10 V; the AD7863-3 offers the common accuracy specifications such as linearity, gain, and offset errors, the signal processing input range of ±2.5 V, while the AD7863-2 part is also specified for dynamic performance parameters can be used in unipolar 0 V to 2.5 V applications. including harmonic distortion and signal-to-noise ratio. 5. The part features very tight aperture delay matching between the two input sample and hold amplifiers. The AD7863 is fabricated in the Analog Devices, Inc. linear compatible CMOS (LC2MOS) process, a mixed technology
Rev. B 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 ©2006 Analog Devices, Inc. All rights reserved.
Document Outline FEATURES GENERAL DESCRIPTION PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TERMINOLOGY CONVERTER DETAILS TRACK-AND-HOLD SECTION REFERENCE SECTION CIRCUIT DESCRIPTION ANALOG INPUT SECTION OFFSET AND FULL-SCALE ADJUSTMENT Positive Full-Scale Adjust (−10 Version) Negative Full-Scale Adjust (−10 Version) TIMING AND CONTROL Read Options OPERATING MODES MODE 1 OPERATION Normal Power, High Sampling Performance MODE 2 OPERATION Power-Down, Auto-Sleep After Conversion AD7863 DYNAMIC SPECIFICATIONS SIGNAL-TO-NOISE RATIO (SNR) EFFECTIVE NUMBER OF BITS TOTAL HARMONIC DISTORTION (THD) INTERMODULATION DISTORTION PEAK HARMONIC OR SPURIOUS NOISE DC LINEARITY PLOT POWER CONSIDERATIONS MICROPROCESSOR INTERFACING AD7863 TO ADSP-2100 INTERFACE AD7863 TO ADSP-2101/ADSP-2102 INTERFACE AD7863 TO TMS32010 INTERFACE AD7863 TO TMS320C25 INTERFACE AD7863 TO MC68000 INTERFACE AD7863 TO 80C196 INTERFACE VECTOR MOTOR CONTROL MULTIPLE AD7863S APPLICATIONS HINTS PC BOARD LAYOUT CONSIDERATIONS GROUND PLANES POWER PLANES SUPPLY DECOUPLING OUTLINE DIMENSIONS ORDERING GUIDE