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 2k 2.5V Simultaneous sampling and conversion REFERENCE 5.2 s conversion time AD7863 Single supply operation Selection of input ranges SIGNAL TRACK/ V A1 SCALING HOLD 10 V for AD7863-10 14-BIT MUX ADC SIGNAL 2.5 V for AD7863-3 V B1 DB0 SCALING OUTPUT 0 V to 2.5 V for AD7863-2 LATCH TRACK/ SIGNAL DB13 High speed parallel interface V A2 HOLD SCALING 14-BIT MUX ADC Low power, 70 mW typical SIGNAL V CS B2 SCALING Power saving mode, 105 W maximum RD Overvoltage protection on analog inputs CONVERSION CLOCK 14-bit lead compatible upgrade to AD7862 CONTROL LOGIC GENERAL DESCRIPTION A0 BUSY AGND AGND DGND CONVST Figure 1. The AD7863 is a high speed, low power, dual 14-bit analog-to- digital converter that operates from a single 5 V supply. process that combines precision bipolar circuits with low power The part contains two 5.2 s successive approximation ADCs, two CMOS logic. It is available in 28-lead SOIC W and SSOP. track/hold amplifiers, an internal 2.5 V reference and a high speed 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 allowing simultaneous sampling and conversion of two simultaneously, thus preserving the relative phase information of 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 s 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 2. The AD7863 operates from a single 5 V supply and for the part allows the input voltage to go to 17 V, 7 V, or +7 V consumes 70 mW typical. The automatic power-down respectively, without causing damage. mode, where the part goes into power-down once conversion is complete and wakes up before the next A single conversion start signal (CONVST) simultaneously places conversion cycle, makes the AD7863 ideal for battery- both track/holds into hold and initiates conversion on both powered or portable applications. channels. The BUSY signal indicates the end of conversion and at 3. The part offers a high speed parallel interface for easy this time the conversion results for both channels are available to be connection to microprocessors, microcontrollers, and read. The first read after a conversion accesses the result from V A1 digital signal processors. or V , and the second read accesses the result from V or V , B1 A2 B2 4. The part is offered in three versions with different analog depending on whether the multiplexer select (A0) is low or high, input ranges. The AD7863-10 offers the standard industrial respectively. Data is read from the part via a 14-bit parallel data bus input range of 10 V the AD7863-3 offers the common with standard CS and RD signals. In addition to the traditional dc signal processing input range of 2.5 V, while the AD7863-2 accuracy specifications such as linearity, gain, and offset errors, the can be used in unipolar 0 V to 2.5 V applications. part is also specified for dynamic performance parameters 5. The part features very tight aperture delay matching including harmonic distortion and signal-to-noise ratio. between the two input sample and hold amplifiers. The AD7863 is fabricated in the Analog Devices, Inc. linear 2 compatible CMOS (LC MOS) 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 Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 06411-001AD7863 TABLE OF CONTENTS Features .............................................................................................. 1 Effective Number of Bits ........................................................... 14 General Description ......................................................................... 1 Total Harmonic Distortion (THD).......................................... 15 Functional Block Diagram .............................................................. 1 Intermodulation Distortion ...................................................... 15 Product Highlights ........................................................................... 1 Peak Harmonic or Spurious Noise........................................... 15 Revision History ............................................................................... 2 DC Linearity Plot ....................................................................... 15 Specifications..................................................................................... 3 Power Considerations................................................................ 16 Timing Characteristics ................................................................ 5 Microprocessor Interfacing........................................................... 17 Absolute Maximum Ratings............................................................ 6 AD7863 to ADSP-2100 Interface ............................................. 17 ESD Caution.................................................................................. 6 AD7863 to ADSP-2101/ADSP-2102 Interface ....................... 17 Pin Configuration and Function Descriptions............................. 7 AD7863 to TMS32010 Interface .............................................. 17 Terminology ...................................................................................... 8 AD7863 to TMS320C25 Interface............................................ 17 Converter Details.............................................................................. 9 AD7863 to MC68000 Interface ................................................ 18 Track-and-Hold Section .............................................................. 9 AD7863 to 80C196 Interface .................................................... 18 Reference Section ......................................................................... 9 Vector Motor Control ................................................................ 18 Circuit Description......................................................................... 10 Multiple AD7863s ...................................................................... 19 Analog Input Section ................................................................. 10 Applications Hints.......................................................................... 20 Offset and Full-Scale Adjustment ............................................ 10 PC Board Layout Considerations............................................. 20 Timing and Control ................................................................... 11 Ground Planes ............................................................................ 20 Operating Modes ............................................................................ 13 Power Planes ............................................................................... 20 Mode 1 Operation ...................................................................... 13 Supply Decoupling ..................................................................... 20 Mode 2 Operation ...................................................................... 13 Outline Dimensions....................................................................... 21 AD7863 Dynamic Specifications ............................................. 14 Ordering Guide .......................................................................... 22 Signal-to-Noise Ratio (SNR)..................................................... 14 REVISION HISTORY 11/06Rev. A to Rev. B Updated Format..................................................................Universal Deleted Applications ........................................................................ 1 Changes to Specifications................................................................ 3 Changes to Absolute Maximum Ratings ....................................... 6 Updated Outline Dimensions ....................................................... 21 Changes to Ordering Guide .......................................................... 22 5/99Rev. 0 to Rev. A Rev. B Page 2 of 24