a
FEATURES
Fast Conversion Time: 5 s
On-Chip Track/Hold
Low Total Unadjusted Error: 1 LSB
Full Power Signal Bandwidth: 50 kHz
Single +5 V Supply
100 ns Data Access Time
Low Power (15 mW typ)
Low Cost
Standard 18-Lead DlPs or 20-Terminal
Surface Mount Packages
LC MOS
5 s 8-Bit ADC with Track/Hold
AD7575
FUNCTIONAL BLOCK DIAGRAM
V
DD
TRACK
AND
HOLD
2
AIN
AGND
V
REF
AD7575
COMP
DAC
CLK
CLOCK
OSCILLATOR
SAR
CS
RD
TP
CONTROL
LOGIC
LATCH AND
THREE STATE
OUTPUT DRIVERS
DB7
DB0
GENERAL DESCRIPTION
BUSY
DGND
The AD7575 is a high speed 8-bit ADC with a built-in track/
hold function. The successive approximation conversion tech-
nique is used to achieve a fast conversion time of 5
µs,
while the
built-in track/hold allows full-scale signals up to 50 kHz (386 mV/µs
slew rate) to be digitized. The AD7575 requires only a single +5 V
supply and a low cost, 1.23 V bandgap reference in order to convert
an input signal range of 0 to 2 V
REF
.
The AD7575 is designed for easy interfacing to all popular 8-bit
microprocessors using standard microprocessor control signals
(CS and
RD)
to control starting of the conversion and reading of
the data. The interface logic allows the AD7575 to be easily
configured as a memory mapped device, and the part can be
interfaced as SLOW-MEMORY or ROM. All data outputs of
the AD7575 are latched and three-state buffered to allow direct
connection to a microprocessor data bus or I/O port.
The AD7575 is fabricated in an advanced, all ion-implanted high
speed Linear Compatible CMOS (LC
2
MOS) process and is
available in a small, 0.3" wide, 18-lead DIP, 18-lead SOIC or in
other 20-terminal surface mount packages.
PRODUCT HIGHLIGHTS
1. Fast Conversion Time/Low Power
The fast, 5
µs,
conversion time of the AD7575 makes it
suitable for digitizing wideband signals at audio and ultra-
sonic frequencies while retaining the advantage of low
CMOS power consumption.
2. On-Chip Track/Hold
The on-chip track/hold function is completely self-contained
and requires no external hold capacitor. Signals with slew
rates up to 386 mV/µs (e.g., 2.46 V peak-to-peak 50 kHz sine
waves) can be digitized with full accuracy.
3. Low Total Unadjusted Error
The zero, full-scale and linearity errors of the AD7575 are so
low that the total unadjusted error at any point on the trans-
fer function is less than 1 LSB, and offset and gain adjust-
ments are not required.
4. Single Supply Operation
Operation from a single +5 V supply with a low cost +1.23 V
bandgap reference allows the AD7575 to be used in 5 V
microprocessor systems without any additional power
supplies.
5. Fast Digital Interface
Fast interface timing allows the AD7575 to interface easily to
the fast versions of most popular microprocessors such as the
Z80H, 8085A-2, 6502B, 68B09 and the DSP processor, the
TMS32010.
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.
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., 1998
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