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a
LC
2
MOS
Complete, 14-Bit Analog I/O System
AD7869
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
World Wide Web Site: http://www.analog.com
FUNCTIONAL BLOCK DIAGRAM
RO DAC
RI DAC
DGND
AD7869
R
R
RO ADC
AGND
CLOCK
R
R
14 - BIT
DAC
DAC
SERIAL
INTERFACE
ADC SERIAL
INTERFACE
14 - BIT
ADC
DAC 3V
REFERENCE
ADC 3V
REFERENCE
TRACK/HOLD
V
SS
V
DD
V
IN
V
OUT
LDAC
TFS
TCLK
DT
CONTROL
RFS
RCLK
DR
CLK
CONVST
FEATURES
Complete 14-Bit l/O System, Comprising
14-Bit ADC with Track/Hold Amplifier
83 kHz Throughput Rate
14-Bit DAC with Output Amplifier
3.5 ms Settling Time
On-Chip Voltage Reference
Operates from 65 V Supplies
Low Power—130 mW typ
Small 0.3" Wide DIP
APPLICATIONS
Digital Signal Processing
Speech Recognition and Synthesis
Spectrum Analysis
High Speed Modems
DSP Servo Control
GENERAL DESCRIPTION
The AD7869 is a complete 14-bit I/O system containing a DAC
and an ADC. The ADC is a successive approximation type with
a track-and-hold amplifier, having a combined throughput rate
of 83 kHz. The DAC has an output buffer amplifier with a set-
tling time of 4 µs to 14 bits. Temperature compensated 3 V bur-
ied Zener references provide precision references for the DAC
and ADC.
Interfacing to both the DAC and ADC is serial, minimizing pin
count and giving a small 24-pin package size. Standard control
signals allow serial interfacing to most DSP machines.
Asynchronous ADC conversion control and DAC updating is
made possible with the
CONVST and LDAC logic inputs.
The AD7869 operates from ±5 V power supplies; the analog in-
put/output range of the ADC/DAC is ±3 V. The part is fully
specified for dynamic parameters such as signal-to-noise ratio
and harmonic distortion as well as traditional dc specifications.
The part is available in a 24-pin, 0.3 inch wide, plastic or her-
metic dual-in-line package (DIP) and in a 28-pin, plastic SOIC
package.
PRODUCT HIGHLIGHTS
1. Complete 14-Bit I/O System.
The AD7869 contains a 14-bit ADC with a track-and-hold
amplifier and a 14-bit DAC with output amplifier. Also in
cluded are separate on-chip voltage references for the DAC
and the ADC.
2. Dynamic Specifications for DSP Users.
In addition to traditional dc specifications, the AD7869 is
specified for ac parameters, including signal-to-noise ratio
and harmonic distortion. These parameters, along with im-
portant timing parameters, are tested on every device.
3. Small Package.
The AD7869 is available in a 24-pin DIP and a 28-pin SOIC
package.
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