a
FEATURES
Fast 12-Bit ADC with 3.8 s Conversion Time
8-Pin Mini-DlP and SOIC
Single 5 V Supply Operation
High Speed, Easy-to-Use, Serial Interface
On-Chip Track/Hold Amplifier
Selection of Input Ranges
10 V for AD7895-10
2.5 V for AD7895-3
0 V to +2.5 V for AD7895-2
High Input Impedance
Low Power: 20 mW max
14-Bit Pin Compatible Upgrade (AD7894)
5 V, 12-Bit, Serial 3.8 s
ADC in 8-Pin Package
AD7895
FUNCTIONAL BLOCK DIAGRAM
REF IN
V
DD
AD7895
TRACK/HOLD
V
IN
SIGNAL
SCALING*
12-BIT
ADC
CONVST
OUTPUT
REGISTER
GND
BUSY
SCLK
SDATA
GENERAL DESCRIPTION
*AD7895-10, AD7895-3
The AD7895 is a fast 12-bit ADC that operates from a single
+5 V supply and is housed in a small 8-pin mini-DIP and 8-pin
SOIC. The part contains a 3.8
µs
successive approximation A/D
converter, an on-chip track/hold amplifier, an on-chip clock and
a high speed serial interface.
Output data from the AD7895 is provided via a high speed,
serial interface port. This two-wire serial interface has a serial
clock input and a serial data output with the external serial clock
accessing the serial data from the part.
In addition to the traditional dc accuracy specifications such as
linearity and full-scale and offset errors, the AD7895 is specified
for dynamic performance parameters, including harmonic
distortion and signal-to-noise ratio.
The part accepts an analog input range of
±
10 V (AD7895-10),
±
2.5 V (AD7895-3), 0 V to 2.5 V (AD7895-2) and operates
from a single +5 V supply, consuming only 20 mW max.
The AD7895 features a high sampling rate mode and, for low
power applications, a proprietary automatic power-down mode
where the part automatically goes into power down once
conversion is complete and “wakes up” before the next conver-
sion cycle.
The part is available in a small, 8-pin, 0.3" wide, plastic dual-in-
line package (mini-DIP) and in an 8-pin, small outline IC (SOIC).
PRODUCT HIGHLIGHTS
1. Fast, 12-Bit ADC in 8-Pin Package
The AD7895 contains a 3.8
µs
ADC, a track/hold amplifier,
control logic and a high speed serial interface, all in an 8-pin
package. This offers considerable space saving over alterna-
tive solutions.
2. Low Power, Single Supply Operation
The AD7895 operates from a single +5 V supply and
consumes only 20 mW. The automatic power-down mode,
where the part goes into power-down once conversion is
complete and “wakes up” before the next conversion cycle,
makes the AD7895 ideal for battery-powered or portable
applications.
3. High Speed Serial Interface
The part provides high speed serial data and serial clock lines
allowing for an easy, two-wire serial interface arrangement.
REV. 0
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: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1996
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