a
FEATURES
Complete 8-Bit DAC
Voltage Output—0 V to 2.56 V
Internal Precision Band-Gap Reference
Single-Supply Operation: 5 V ( 10%)
Full Microprocessor Interface
Fast: 1 s Voltage Settling to 1/2 LSB
Low Power: 75 mW
No User Trims Required
Guaranteed Monotonic Over Temperature
All Errors Specified T
MIN
to T
MAX
Small 16-Lead DIP or 20-Lead PLCC Package
Low Cost
DACPORT Low Cost, Complete
P-Compatible 8-Bit DAC
AD557*
FUNCTIONAL BLOCK DIAGRAM
CONTROL
INPUTS
GND
CS CE
l
2
L
CONTROL
LOGIC
DIGITAL INPUT DATA (BUS)
BIT1
(MSB)
BIT8
(LSB)
+V
CC
l
2
L LATCHES
LSB
MSB
8-BIT VOLTAGE-SWITCHING
D-TO-A CONVERTER
OUTPUT
AMP
V
OUT
V
OUT
SENSE A
BAND-GAP
REFERENCE
V
OUT
SENSE B
GND
CONTROL
AMP
AD557
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
The AD557 DACPORT is a complete voltage-output 8-bit
digital-to-analog converter, including output amplifier, full
microprocessor interface and precision voltage reference on a
single monolithic chip. No external components or trims are
required to interface, with full accuracy, an 8-bit data bus to an
analog system.
The low cost and versatility of the AD557 DACPORT are the
result of continued development in monolithic bipolar technologies.
The complete microprocessor interface and control logic is
implemented with integrated injection logic (I
2
L), an extremely
dense and low-power logic structure that is process-compatible
with linear bipolar fabrication. The internal precision voltage
reference is the patented low-voltage band-gap circuit which
permits full-accuracy performance on a single 5 V power supply.
Thin-film silicon-chromium resistors provide the stability required
for guaranteed monotonic operation over the entire operating
temperature range, while laser-wafer trimming of these thin-film
resistors permits absolute calibration at the factory to within
±
2.5 LSB; thus, no user-trims for gain or offset are required. A
new circuit design provides voltage settling to
±
1/2 LSB for a
full-scale step in 800 ns.
The AD557 is available in two package configurations. The
AD557JN is packaged in a 16-lead plastic, 0.3"-wide DIP. For
surface mount applications, the AD557JP is packaged in a
20-lead JEDEC-standard PLCC. Both versions are specified
over the operating temperature range of 0°C to 70°C.
DACPORT is a registered trademark of Analog Devices, Inc.
*Covered
by U.S. Patent Nos. 3,887,863; 3,685,045; 4,323,795; other
patents pending.
®
1. The 8-bit I
2
L input register and fully microprocessor-
compatible control logic allow the AD557 to be directly
connected to 8- or 16-bit data buses and operated with stan-
dard control signals. The latch may be disabled for direct
DAC interfacing.
2. The laser-trimmed on-chip SiCr thin-film resistors are
calibrated for absolute accuracy and linearity at the factory.
Therefore, no user trims are necessary for full rated accuracy
over the operating temperature range.
3. The inclusion of a precision low-voltage band-gap reference
eliminates the need to specify and apply a separate reference
source.
4. The AD557 is designed and specified to operate from a
single 4.5 V to 5.5 V power supply.
5. Low digital input currents, 100
µA
max, minimize bus loading.
Input thresholds are TTL/low voltage CMOS compatible.
6. The single-chip, low power I
2
L design of the AD557 is inher-
ently more reliable than hybrid multichip or conventional
single-chip bipolar designs.
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., 2001
AD [ ANALOG DEVICES ]
