2 LC MOS Complete, 12-Bit, 100 kHz, Sampling ADCs AD7870/AD7875/AD7876 FEATURES FUNCTIONAL BLOCK DIAGRAM AGND REF OUT V V IN DD Complete monolithic 12-bit ADCs with 2 s track-and-hold amplifier AD7870/AD7875/ 8 s ADC AD7876 INPUT On-chip reference SCALING Laser-trimmed clock TRACK-AND-HOLD Parallel, byte, and serial digital interface 72 dB SNR at 10 kHz input frequency COMP 3V 12-BIT (AD7870, AD7875) REFERENCE DAC 57 ns data access time Low power: 60 mW typical CLK CLOCK Variety of input ranges SAR + 3 V for AD7870 COUNTER 0 V to +5 V for AD7875 12/8/CLK 10 V for AD7876 CONTROL LOGIC PARALLEL CONVST AND SERIAL INTERFACE CS RD BUSY/INT DB11 DB0 DGND V SS Figure 1. GENERAL DESCRIPTION The AD7870/AD7875/AD7876 are fast, complete, 12-bit The parts are available in a 24-pin, 0.3 inch-wide, plastic or analog-to-digital converters (ADCs). These converters consist hermetic dual-in-line package (DIP). The AD7870 and AD7875 of a track-and-hold amplifier, an 8 s successive approximation are available in a 28-pin plastic leaded chip carrier (PLCC), ADC, a 3 V buried Zener reference, and versatile interface logic. while the AD7876 is available and in a 24-pin small outline (SOIC) package. The ADCs feature a self-contained internal clock which is laser trimmed to guarantee accurate control of conversion time. No PRODUCT HIGHLIGHTS external clock timing components are required the on-chip 1. Complete 12-bit ADC on a chip. clock may be overridden by an external clock if required. The AD7870/AD7875/AD7876 provide all the functions The parts offer a choice of three data output formats: a single, necessary for analog-to-digital conversion and combine a parallel, 12-bit word two 8-bit bytes or serial data. Fast bus 12-bit ADC with internal clock, track-and-hold amplifier access times and standard control inputs ensure easy interfacing and reference on a single chip. to modern microprocessors and digital signal processors. 2. Dynamic specifications for DSP users. All parts operate from 5 V power supplies. The AD7870 and The AD7870 and AD7875 are fully specified and tested for AD7876 accept input signal ranges of 3 V and 10 V, respec- ac parameters, including signal-to-noise ratio, harmonic tively, while the AD7875 accepts a unipolar 0 V to +5 V input distortion and intermodulation distortion. range. The parts can convert full power signals up to 50 kHz. 3. Fast microprocessor interface. The AD7870/AD7875/AD7876 feature dc accuracy specifica- Data access times of 57 ns make the parts compatible with tions, such as linearity, full-scale and offset error. In addition, modern 8-bit and 16-bit microprocessors and digital signal the AD7870 and AD7875 are fully specified for dynamic processors. Key digital timing parameters are tested and performance parameters including distortion and signal-to- guaranteed over the full operating temperature range. noise ratio. Rev. C 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 19972009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 07730-001AD7870/AD7875/AD7876 TABLE OF CONTENTS Features .............................................................................................. 1 Offset And Full-Scale AdjustmentAD7876 ........................ 13 Functional Block Diagram .............................................................. 1 Offset And Full-Scale AdjustmentAD7875 ........................ 13 General Description ......................................................................... 1 Timing and Control ....................................................................... 14 Product Highlights ........................................................................... 1 Data Output Formats ................................................................. 14 Revision History ............................................................................... 2 Mode 1 Interface ......................................................................... 14 Specif icat ions ..................................................................................... 3 Mode 2 Interface ......................................................................... 15 AD7870 Specifications ................................................................. 3 Dynamic Specifications ............................................................. 16 AD7875/AD7876 Specifications ................................................. 4 Microprocessor Interface ............................................................... 19 Timing Characteristics ................................................................ 6 Parallel Read Interfacing ........................................................... 19 Absolute Maximum Ratings ............................................................ 7 Two-Byte Read Interfacing ....................................................... 19 ESD Caution .................................................................................. 7 Serial Interfacing ........................................................................ 20 Pin Configurations and Function Descriptions ........................... 8 Standalone Operation ................................................................ 21 Load Circuits ................................................................................... 10 Applications Information .............................................................. 22 Converter Details ............................................................................ 11 Layout Hints ................................................................................ 22 Internal Reference ...................................................................... 11 Noise ............................................................................................ 22 Track-and-Hold Amplifier ........................................................ 11 Outline Dimensions ....................................................................... 23 Analog Input ............................................................................... 11 Ordering Guide .......................................................................... 25 Offset And Full-Scale AdjustmentAD7870 ........................ 12 REVISION HISTORY 2/09Rev. B to Rev. C Updated Format .................................................................. Universal Reorganized Layout ............................................................ Universal Deleted S Version ................................................................ Universal Changes to Internal Clock Parameter, Table 1 and Added Endnote to Table 1 ............................................................... 4 Changes to Internal Clock Parameter, Table 2 .............................. 5 Changes to Mode 1 Interface Section .......................................... 14 Deleted Data Acquisition Board and Interface Connections Sections and Figure 26 ................................................................... 15 Deleted Figure 27 and Power Supply Connections, Shorting Plug Options and Components List Sections ............................. 16 Deleted Figure 28 and Figure 29 ................................................... 17 Deleted Figure 30 and Figure 31 ................................................... 18 Updated Outline Dimensions ....................................................... 23 Changes to Ordering Guide .......................................................... 25 Rev. C Page 2 of 28