2 LC MOS 16-Bit Voltage Output DAC AD7846 FEATURES FUNCTIONAL BLOCK DIAGRAM V V CC DD 16-bit monotonicity over temperature 21 4 2 LSBs integral linearity error V REF+ 7 Microprocessor compatible with readback capability AD7846 R R 6 R A2 IN Unipolar or bipolar output R 16 Multiplying capability SEGMENT R Low power (100 mW typical) SWITCH 5 V A3 OUT MATRIX 12-BIT DAC R 12 A1 23 CS V 8 REF DAC LATCH 22 4 R/W CONTROL 12 LOGIC 25 LDAC I/O LATCH 24 CLR 9 10 3 20 V DB15 DB0 DGND SS Figure 1. GENERAL DESCRIPTION The AD7846 is a 16-bit DAC constructed with the Analog Devices, to 00000 or 10000 depending on the state of R/W. This 2 Inc., LC MOS process. It has VREF+ and VREF reference inputs means that the DAC output can be reset to 0 V in both the and an on-chip output amplifier. These can be configured to unipolar and bipolar configurations. give a unipolar output range (0 V to +5 V, 0 V to +10 V) or The AD7846 is available in 28-lead plastic, ceramic, and PLCC bipolar output ranges (5 V, 10 V). packages. The DAC uses a segmented architecture. The four MSBs in the PRODUCT HIGHLIGHTS DAC latch select one of the segments in a 16-resistor string. 1. 16-Bit Monotonicity Both taps of the segment are buffered by amplifiers and fed to a The guaranteed 16-bit monotonicity over temperature 12-bit DAC, which provides a further 12 bits of resolution. This makes the AD7846 ideal for closed-loop applications. architecture ensures 16-bit monotonicity. Excellent integral 2. Readback linearity results from tight matching between the input offset The ability to read back the DAC register contents voltages of the two buffer amplifiers. minimizes software routines when the AD7846 is used in In addition to the excellent accuracy specifications, the AD7846 ATE systems. also offers a comprehensive microprocessor interface. There are 3. Power Dissipation CS 16 data I/O pins, plus control lines ( , R/W, LDAC and CLR). Power dissipation of 100 mW makes the AD7846 the R/W and CS allow writing to and reading from the I/O latch. lowest power, high accuracy DAC on the market. This is the readback function, which is useful in ATE applications. LDAC allows simultaneous updating of DACs in a multi-DAC CLR system and the line will reset the contents of the DAC latch Rev. G 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 20002010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 08490-001AD7846 TABLE OF CONTENTS Features .............................................................................................. 1 Output Stage ................................................................................ 12 Functional Block Diagram .............................................................. 1 Unipolar Binary Operation ........................................................... 13 General Description ......................................................................... 1 Bipolar Operation ........................................................................... 14 Product Highlights ........................................................................... 1 Multiplying Operation ............................................................... 14 Revision History ............................................................................... 2 Position Measurement Application .............................................. 15 Specif icat ions ..................................................................................... 3 Microprocessor Interfacing ........................................................... 16 AC Performance Characteristics ................................................ 4 AD7846-to-8086 Interface ........................................................ 16 Timing Characteristics ................................................................ 5 AD7846-to-MC68000 Interface ............................................... 16 Absolute Maximum Ratings ............................................................ 6 Digital Feedthrough ....................................................................... 17 ESD Caution .................................................................................. 6 Application Hints ........................................................................... 18 Pin Configurations and Function Descriptions ........................... 7 Noise ............................................................................................ 18 Typical Performance Characteristics ............................................. 8 Grounding ................................................................................... 18 Terminology .................................................................................... 10 Printed Circuit Board Layout ................................................... 18 Circuit Description ......................................................................... 11 Outline Dimensions ....................................................................... 20 Digital Section ............................................................................. 11 Ordering Guide .......................................................................... 22 Digital-to-Analog Conversion .................................................. 11 REVISION HISTORY 4/10Rev. F to Rev. G Change to Figure 1 ........................................................................... 1 12/09Rev. E to Rev. F Updated Format .................................................................. Universal Changes to Table 4 ............................................................................ 6 Deleted Other Output Voltage Ranges Section ............................ 9 Deleted Figure 20 and Table 5 Renumbered Sequentially ......... 9 Deleted Test Application Section and Figure 21 ........................ 10 Deleted Figure 29 to Figure 31 ...................................................... 14 Changes to Printed Circuit Board Layout Section ..................... 18 Updated Outline Dimensions ....................................................... 20 Changes to Ordering Guide .......................................................... 22 Rev. G Page 2 of 24