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PDF AD573 Data sheet ( Hoja de datos )
| Número de pieza | AD573 | |
| Descripción | 10-Bit A/D Converter | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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a
10-Bit A/D Converter
AD573*
FEATURES
Complete 10-Bit A/D Converter with Reference, Clock
and Comparator
Full 8- or 16-Bit Microprocessor Bus Interface
Fast Successive Approximation Conversion—20 s typ
No Missing Codes Over Temperature
Operates on +5 V and –12 V to –15 V Supplies
Low Cost Monolithic Construction
PRODUCT DESCRIPTION
The AD573 is a complete 10-bit successive approximation
analog-to-digital converter consisting of a DAC, voltage refer-
ence, clock, comparator, successive approximation register
(SAR) and three state output buffers—all fabricated on a single
chip. No external components are required to perform a full
accuracy 10-bit conversion in 20 µs.
The AD573 incorporates advanced integrated circuit design and
processing technologies. The successive approximation function
is implemented with I2L (integrated injection logic). Laser trim-
ming of the high stability SiCr thin-film resistor ladder network
insures high accuracy, which is maintained with a temperature
compensated subsurface Zener reference.
Operating on supplies of +5 V and –12 V to –15 V, the AD573
will accept analog inputs of 0 V to +10 V or –5 V to +5 V. The
trailing edge of a positive pulse on the CONVERT line initiates
the 20 µs conversion cycle. DATA READY indicates completion
of the conversion. HIGH BYTE ENABLE (HBE) and LOW
BYTE ENABLE (LBE) control the 8-bit and 2-bit three state
output buffers.
The AD573 is available in two versions for the 0°C to +70°C
temperature range, the AD573J and AD573K. The AD573S
guarantees ± 1 LSB relative accuracy and no missing codes from
–55°C to +125°C.
Three package configurations are offered. All versions are offered
in a 20-pin hermetically sealed ceramic DIP. The AD573J and
AD573K are also available in a 20-pin plastic DIP or 20-pin
leaded chip carrier.
*Protected by U.S. Patent Nos. 3,940,760; 4,213,806; 4,136,349; 4,400,689;
and 4,400,690.
FUNCTIONAL BLOCK DIAGRAM
V+ V–
DIGITAL
COMMON CONVERT
ANALOG
IN
ANALOG
COMMON
5k
COMP-
ARATOR
BIPOLAR
OFFSET
CONTROL
10-BIT
CURRENT
OUTPUT
DAC
10-BIT
SAR
INT
CLOCK
DATA
READY
BURIED ZENER REF
AD573
MSB
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
HIGH
BYTE
DB1
DB0
LSB
LOW
BYTE
HBE
LBE
PRODUCT HIGHLIGHTS
l. The AD573 is a complete 10-bit A/D converter. No external
components are required to perform a conversion.
2. The AD573 interfaces to many popular microprocessors
without external buffers or peripheral interface adapters. The
10 bits of output data can be read as a 10-bit word or as 8-
and 2-bit words.
3. The device offers true 10-bit accuracy and exhibits no miss-
ing codes over its entire operating temperature range.
4. The AD573 adapts to either unipolar (0 V to +10 V) or
bipolar (–5 V to +5 V) analog inputs by simply grounding or
opening a single pin.
5. Performance is guaranteed with +5 V and –12 V or –15 V
supplies.
6. The AD573 is available in a version compliant with MIL-STD-
883. Refer to the Analog Devices Military Products Data-
book or current /883B data sheet for detailed specifications.
REV. A
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
Fax: 617/326-8703
1 page  
BIPOLAR CONNECTION
To obtain the bipolar –5 V to +5 V range with an offset binary
output code, the bipolar offset control pin is left open.
A –5.000 volt signal will give a 10-bit code of 00000000 00; an
input of 0.000 volts results in an output code of 10000000 00
and +4.99 volts at the input yields the 11111111 11 code. The
nominal transfer curve is shown in Figure 6.
AD573
SAMPLE-HOLD AMPLIFIER CONNECTION TO THE
AD573
Many situations in high speed acquisition systems or digitizing
rapidly changing signals require a sample-hold amplifier (SHA)
in front of the A/D converter. The SHA can acquire and hold a
signal faster than the converter can perform a conversion. A
SHA can also be used to accurately define the exact point in
time at which the signal is sampled. For the AD573, a SHA can
also serve as a high input impedance buffer.
Figure 8 shows the AD573 connected to the AD582 monolithic
SHA for high speed signal acquisition. In this configuration, the
AD582 will acquire a 10 volt signal in less than 10 µs with a
droop rate less than 100 µV/ms.
Figure 6. AD573 Transfer Curve— Bipolar Operation
Note that in the bipolar mode, the code transitions are offset
1/2 LSB such that an input voltage of 0 volts ± 5 mV yields the
code representing zero (10000000 00). Each output code is then
centered on its nominal input voltage.
Full-Scale Calibration
Full-Scale Calibration is accomplished in the same manner as in
unipolar operation except the full scale input voltage is +4.985
volts.
Negative Full-Scale Calibration
The circuit in Figure 4a can also be used in bipolar operation to
offset the input voltage (nominally –5 V) which results in the
00000000 00 code. R2 should be omitted to obtain a symmetri-
cal range.
The bipolar offset control input is not directly TTL compatible
but a TTL interface for logic control can be constructed as
shown in Figure 7.
Figure 8. Sample-Hold Interface to the AD573
DR goes high after the conversion is initiated to indicate that
reset of the SAR is complete. In Figure 8 it is also used to put
the AD582 into the hold mode while the AD573 begins its con-
version cycle. (The AD582 settles to final value well in advance
of the first comparator decision inside the AD573).
DR goes low when the conversion is complete placing the
AD582 back in the sample mode. Configured as shown in Fig-
ure 8, the next conversion can be initiated after a 10 µs delay to
allow for signal acquisition by the AD582.
Observe carefully the ground, supply, and bypass capacitor con-
nections between the two devices. This will minimize ground
noise and interference during the conversion cycle.
Figure 7. Bipolar Offset Controlled by Logic Gate
Gate Output = 1 Unipolar 0–10 V Input Range
Gate Output = 0 Bipolar ±5 V Input Range
REV. A
GROUNDING CONSIDERATIONS
The AD573 provides separate Analog and Digital Common
connections. The circuit will operate properly with as much as
± 200 mV of common-mode voltage between the two commons.
This permits more flexible control of system common bussing
and digital and analog returns.
In normal operation, the Analog Common terminal may gener-
ate transient currents of up to 2 mA during a conversion. In ad-
dition a static current of about 2 mA will flow into Analog
Common in the unipolar mode after a conversion is complete.
The Analog Common current will be modulated by the varia-
tions in input signal.
The absolute maximum voltage rating between the two com-
mons is ± 1 volt. It is recommended that a parallel pair of
back-to-back protection diodes be connected between the com-
mons if they are not connected locally.
–5–
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet AD573.PDF ] | |
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