REV. A
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a
AD7899
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
5 V Single Supply
14-Bit 400 kSPS ADC
FUNCTIONAL BLOCK DIAGRAM
TRACK/HOLD
AVDD
V
REF
BUSY/EOC
CLKIN
RD
CS
AD7899
V
INB
V
INA
+
–
14-BIT
ADC
OUTPUT
LATCH
DB0
DB13
CONVERSION
CONTROL
LOGIC
INT/EXT
CLOCK
SELECT
INT
CLOCK
SIGNAL
SCALING
2.5V
REFERENCE
6k⍀
V
DRIVE
CONVST OPGNDGND
STBY
FEATURES
Fast (2.2 s) 14-Bit ADC
400 kSPS Throughput Rate
0.3 s Track/Hold Acquisition Time
Single Supply Operation
Selection of Input Ranges: ⴞ10 V, ⴞ5 V and ⴞ2.5 V
0 V to 2.5 V and 0 V to 5 V
High-Speed Parallel Interface which Also Allows
Interfacing to 3 V Processors
Low Power, 80 mW Typ
Power-Saving Mode, 20 W Typ
Overvoltage Protection on Analog Inputs
Power-Down Mode via STBY Pin
GENERAL DESCRIPTION
The AD7899 is a fast, low-power, 14-bit A/D converter that
operates from a single 5 V supply. The part contains a 2.2 µs
successive-approximation ADC, a track/hold amplifier, 2.5 V
reference, on-chip clock oscillator, signal conditioning circuitry,
and a high-speed parallel interface. The part accepts analog input
ranges of ±10 V, ± 5 V, ± 2.5 V, 0 V to 2.5 V, and 0 V to 5 V.
Overvoltage protection on the analog input for the part allows
the input voltage to be exceeded without damaging the parts.
Speed of conversion can be controlled either by an internally
trimmed clock oscillator or by an external clock.
A conversion start signal (CONVST) places the track/hold into
hold mode and initiates conversion. The BUSY/EOC signal
indicates the end of the conversion.
Data is read from the part via a 14-bit parallel data bus using the
standard CS and RD signals. Maximum throughput for the
AD7899 is 400 kSPS.
The AD7899 is available in a 28-lead SOIC and SSOP packages.
PRODUCT HIGHLIGHTS
1. The AD7899 features a fast (2.2 µs) ADC allowing through-
put rates of up to 400 kSPS.
2. The AD7899 operates from a single 5 V supply and con-
sumes only 80 mW typ making it ideal for low power and
portable applications.
3. The part offers a high-speed parallel interface. The interface
can operate in 3 V and 5 V mode allowing for easy connec-
tion to 3 V or 5 V microprocessors, microcontrollers, and
digital signal processors.
4. The part is offered in three versions with different analog
input ranges. The AD7899-1 offers the standard industrial
ranges of ±10 V and ±5 V; the AD7899-2 offers a unipolar
range of 0 V to 2.5 or 0 V to 5 V, and the AD7899-3 has an
input range of ±2.5 V.
