a
FEATURES
Two 12-Bit CMOS DAC Channels with
On-Chip Voltage Reference
Output Amplifiers
Three Selectable Output Ranges per Channel
–5 V to +5 V, 0 V to +5 V, 0 V to +10 V
Serial Interface
125 kHz DAC Update Rate
Small Size: 16-Lead DIP or SOIC
Low Power Dissipation
APPLICATIONS
Process Control
Industrial Automation
Digital Signal Processing Systems
Input/Output Ports
LC MOS
Dual 12-Bit Serial DACPORT
®
AD7249
FUNCTIONAL BLOCK DIAGRAM
V
DD
V
SS
2
AD7249
REFOUT
2R
R
OFSA
2R
REFIN
12-BIT
DAC A
A1
2R
V
OUTA
R
OFSB
2R
AGND
12-BIT
DAC B
DGND
INPUT SHIFT REGISTER
A2
V
OUTB
GENERAL DESCRIPTION
The AD7249 DACPORT contains a pair of 12-bit, voltage-
output, digital-to-analog converters with output amplifiers and
Zener voltage reference on a monolithic CMOS chip. No exter-
nal trims are required to achieve full specified performance.
The output amplifiers are capable of developing +10 V across a
2 kΩ load. The output voltage ranges with single supply opera-
tion are 0 V to +5 V or 0 V to +10 V, while an additional bipolar
±
5 V output range is available with dual supplies. The ranges
are selected using the internal gain resistor.
Interfacing to the AD7249 is serial, minimizing pin count and
allowing a small package size. Standard control signals allow
interfacing to most DSP processors and microcontrollers. The
data stream consists of 16 bits, DB15 to DB13 are don’t care
bits, the 13th bit (DB12) is used as the channel select bit and
the remaining 12 bits (DB11 to DB0) contain the data to update
the DAC. The 16-bit data word is clocked into the input register
on each falling SCLK edge.
The data format is natural binary in both unipolar ranges, while
either offset binary or twos complement format may be selected
in the bipolar range. A
CLR
function is provided which sets the
output to 0 V in both unipolar ranges and in the twos comple-
ment bipolar range, while with offset binary data format, the
output is set to –REFIN. This function is useful as a power-on
reset as it allows the outputs to be set to a known voltage level.
SCLK
SDIN
SYNC BIN/COMP CLR
LDAC
The AD7249 features a serial interface which allows easy con-
nection to both microcomputers and 16-bit digital signal proces-
sors with serial ports. The serial data may be applied at rates up
to 2 MHz allowing a DAC update rate of 125 kHz.
The AD7249 is fabricated on linear compatible CMOS
(LC
2
MOS), an advanced, mixed technology process. It is pack-
aged in 16-lead DIP and 16-lead SOIC packages.
PRODUCT HIGHLIGHTS
1. Two complete 12-bit DACPORTs
The AD7249 contains two complete voltage output, 12-bit
DACs in both 16-lead DIP and SOIC packages.
2. Single or dual supply operation
3. Minimum 3-wire interface to most DSP processors
4. DAC update rate—125 kHz
DACPORT is a registered trademark of Analog Devices, Inc.
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 rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
AD [ ANALOG DEVICES ]
