Serial Input, 14-Bit/16-Bit DAC AD7849 FEATURES FUNCTIONAL BLOCK DIAGRAM V V DD CC 14-bit/16-bit multiplying DAC R V REF+ Guaranteed monotonicity R OFS R Output control on power-up and power-down internal or A1 R external control RST IN G1 Versatile serial interface A3 V OUT 10-BIT/ R DAC clears to 0 V in both unipolar and bipolar output ranges 12-BIT DAC G2 LOGIC 10/ 12 CIRCUITRY APPLICATIONS A2 DAC R LATCH V REF Industrial process controls VOLTAGE 10/ AGND MONITOR 4 12 PC analog I/O boards RST OUT Instrumentation INPUT LATCH AD7849 INPUT SHIFT REGISTER/ CONTROL LOGIC DGND SDIN SCLK SYNC CLR BIN/ DCEN SDOUT LDAC V SS COMP Figure 1. GENERAL DESCRIPTION The AD7849 is a 14-bit/16-bit serial input multiplying digital- The AD7849 has a versatile serial interface structure and can be to-analog converter (DAC). The DAC architecture ensures controlled over three lines to facilitate opto-isolator applications. excellent differential linearity performance, and monotonicity is SDOUT is the output of the on-chip shift register and can be guaranteed to 14 bits for the A grade and to 16 bits for all other used in a daisy-chain fashion to program devices in the multi- grades over the specified temperature ranges. channel system. The daisy-chain enable (DCEN) input controls this function. During power-up and power-down sequences (when the supply voltages are changing), the VOUT pin is clamped to 0 V via a low The BIN/COMP pin sets the DAC coding with BIN/COMP set impedance path. To prevent the output of A3 from being shorted to to 0, the coding is straight binary and with BIN/COMP set to 1, 0 V during this time, Transmission Gate G1 is also opened. These the coding is twos complement. This allows the user to reset the conditions are maintained until the power supplies stabilize, DAC to 0 V in both the unipolar and bipolar output ranges. and a valid word is written to the DAC register. At this time, G2 The part is available in a 20-lead PDIP package and a 20-lead SOIC opens and G1 closes. Both transmission gates are also externally package. controllable via the reset in (RSTIN) control input. For instance, if the RSTIN input is driven from a battery supervisor chip, then at power-off or during a brown out, the RSTIN input is driven low to open G1 and close G2. The DAC must be reloaded, with RSTIN high, to reenable the output. Conversely, the on-chip RSTOUT voltage detector output ( ) is also available to the user to control other parts of the system. 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 19952011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 16-SEGMENT SWITCH MATRIX 01008-001AD7849 TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ..............................................8 Applications....................................................................................... 1 Terminology.................................................................................... 10 Functional Block Diagram .............................................................. 1 Circuit Description......................................................................... 11 General Description ......................................................................... 1 Digital-to-Analog Conversion.................................................. 11 Revision History ............................................................................... 2 Digital Interface.......................................................................... 12 Specifications..................................................................................... 3 Applying the AD7849 ................................................................ 13 Reset Specifications...................................................................... 4 Microprocessor Interfacing....................................................... 15 AC Performance Characteristics ................................................ 5 Applications Information .............................................................. 17 Timing Characteristics ................................................................ 5 Opto-Isolated Interface ............................................................. 17 Absolute Maximum Ratings............................................................ 6 Outline Dimensions....................................................................... 18 ESD Caution.................................................................................. 6 Ordering Guide .......................................................................... 19 Pin Configuration and Function Descriptions............................. 7 REVISION HISTORY 3/11Rev. B to Rev. C Deleted 20-Lead CERDIP (Q-20) Package and T Version .............................................................................Universal Updated Format..................................................................Universal Deleted AD7849-to-ADSP-2101/ADSP-2102 Interface Section and Figure 20 Renumbered Sequentially.................................... 12 Rev. C Page 2 of 20