2
LC MOS Quad 8-Bit DAC
with Separate Reference Inputs
a
AD7225
FEATURES
FUNCTIO NAL BLO CK D IAGRAM
Four 8-Bit DACs w ith Output Am plifiers
Separate Reference Input for Each DAC
P Com patible w ith Double-Buffered Inputs
Sim ultaneous Update of All Four Outputs
Operates w ith Single or Dual Supplies
Extended Tem perature Range Operation
No User Trim s Required
Skinny 24-Pin DIP, SOIC and 28-Term inal Surface
Mount Packages
GENERAL D ESCRIP TIO N
T he AD7225 contains four 8-bit voltage output digital-to-
analog converters, with output buffer amplifiers and interface
logic on a single monolithic chip. Each D/A converter has a
separate reference input terminal. No external trims are re-
quired to achieve full specified performance for the part.
P RO D UCT H IGH LIGH TS
1. DACs and Amplifiers on CMOS Chip
T he single-chip design of four 8-bit DACs and amplifiers al-
lows a dramatic reduction in board space requirements and
offers increased reliability in systems using multiple convert-
ers. Its pinout is aimed at optimizing board layout with all
analog inputs and outputs at one end of the package and all
digital inputs at the other.
T he double-buffered interface logic consists of two 8-bit regis-
ters per channel–an input register and a DAC register. Control
inputs A0 and A1 determine which input register is loaded when
WR goes low. Only the data held in the DAC registers deter-
mines the analog outputs of the converters. T he double-
buffering allows simultaneous update of all four outputs under
control of LDAC. All logic inputs are T T L and CMOS (5 V)
level compatible and the control logic is speed compatible with
most 8-bit microprocessors.
2. Single or Dual Supply Operation
T he voltage-mode configuration of the AD7225 allows single
supply operation. T he part can also be operated with dual
supplies giving enhanced performance for some parameters.
Specified performance is guaranteed for input reference voltages
from +2 V to +12.5 V when using dual supplies. T he part 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.
3. Versatile Interface Logic
T he AD7225 has a common 8-bit data bus with individual
DAC latches, providing a versatile control architecture for
simple interface to microprocessors. T he double-buffered in-
terface allows simultaneous update of the four outputs.
T he AD7225 is fabricated on an all ion-implanted high-speed
Linear Compatible CMOS (LC2MOS) process which has been
specifically developed to integrate high speed digital logic cir-
cuits and precision analog circuitry on the same chip.
4. Separate Reference Input for Each DAC
T he AD7225 offers great flexibility in dealing with input sig-
nals with a separate reference input provided for each DAC
and each reference having variable input voltage capability.
REV. B
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reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
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