AD7868_15 Datasheet, PDF (1/16 Pages) Analog Devices – LC MOS Complete, 12-Bit Analog I/O System

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LC²MOS
Complete, 12-Bit Analog I/O System
AD7868
FEATURES
Complete 12-Bit I/O System, Comprising:
12-Bit ADC with Track/Hold Amplifier
83 kHz Throughout Rate
72 dB SNR
12-Bit DAC with Output Amplifier
3 ␮s Settling Time
72 dB SNR
On-Chip Voltage Reference
Operates from ؎5 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 AD7868 is a complete 12-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
settling time of 3 µs to 12 bits. Temperature compensated 3 V
buried 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. Asyn-
chronous ADC conversion control and DAC updating is made
possible with the CONVST and LDAC logic inputs.
The AD7868 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" wide, plastic or hermetic
dual-in-line package (DIP) and in a 28-pin, plastic SOIC
package.
FUNCTIONAL BLOCK DIAGRAM
V_DD
R
R
RI DAC
LDAC
TFS
TCLK
DT
CONTROL
RFS
RCLK
DR
CLK
CONVST
CLOCK
AD7868
DGND
12-BIT
DAC
DAC SERIAL
INTERFACE
ADC SERIAL
INTERFACE
12-BIT
ADC
DAC 3V
REFERENCE
ADC 3V
REFERENCE
R
R
TRACK/HOLD
V_SS
AGND
V_OUT
RO DAC
RO ADC
V_IN
PRODUCT HIGHLIGHTS
1. Complete 12-Bit I/O System.
The AD7868 contains a 12-bit ADC with a track-and-hold
amplifier and a 12-bit DAC with output amplifier. Also
included 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 AD7868 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 AD7868 is available in a 24-pin DIP and a 28-pin SOIC
package.
REV. B
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.
© Analog Devices, Inc., 1996
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
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