LC
2
MOS Octal 8-Bit DAC
Data Sheet
AD7228
Rev. C Document Feedback
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FEATURES
Eight 8-bit DACs with output amplifiers
Operates with single or dual supplies
Microprocessor-compatible (95 ns
WR
pulse)
No user trims required
Skinny 24-lead PDIP, CERDIP, and SOIC packages, and a
28-lead PLCC surface-mount package
FUNCTIONAL BLOCK DIAGRAM
V
SS
GND
LATCH 5 DAC 5
LATCH 6 DAC 6
LATCH 7 DAC 7
LATCH 8
CONTROL
LOGIC
DAC 8
V
OUT8
8
WR
A1
A0
A2
AD7228
10 12
2
3
4
5
6
7
8
9
21
22
23
24
11 1
V
OUT7
7
V
OUT6
6
V
OUT5
5
V
OUT4
4
V
OUT3
3
V
OUT2
2
V
OUT1
1
LATCH 1 DAC 1
LATCH 2 DAC 2
LATCH 3 DAC 3
LATCH 4 DAC 4
DATA BUS
REF
DD
MSB
DATA
(8-BIT)
LSB
13
20
13034-001
Figure 1.
GENERAL DESCRIPTION
The AD7228 contains eight 8-bit voltage mode digital-to- analog
converters (DACs), with output buffer amplifiers and interface
logic on a single monolithic chip. No external trims are required
to achieve the full specified performance for the device.
Separate on-chip latches are provided for each of the eight DACs.
Data is transferred into the data latches through a common
8-bit, TTL/CMOS-compatible input port (5 V). The A0, A1,
and A2 address inputs determine which latch is loaded when
WR
goes low. The control logic is speed compatible with most
8-bit microprocessors.
Specified performance is guaranteed for input reference voltages
from 2 V to 10 V when using dual supplies. The device is also
specified for single-supply operation using a reference of 10 V.
Each output buffer amplifier is capable of developing 10 V across a
2 kΩ load.
The AD7228 is fabricated on an all ion implanted, high speed,
linear-compatible CMOS (LC
2
MOS) process, specifically
developed to integrate high speed digital logic circuits and
precision analog circuits on the same chip.
PRODUCT HIGHLIGHTS
1. The single chip design of eight 8-bit DACs and amplifiers
allows a dramatic reduction in board space requirements
and offers increased reliability in systems using multiple
converters. The PDIP, CERDIP, and SOIC pinout is aimed at
optimizing board layout with all analog inputs and outputs at
one side of the package and all digital inputs at the other.
2. The voltage mode configuration of the DACs allows single
supply operation of the AD7228. The device can also be
operated with dual supplies giving enhanced performance
for some parameters.
3. The AD7228 has a common 8-bit data bus with individual
DAC latches, providing a versatile control architecture for
simple interface to microprocessors. All latch enable signals
are level triggered and speed compatible with most high
performance 8-bit microprocessors.
