LC
2
MOS
Microprocessor-Compatible 14-Bit DAC
AD7538
Rev. B
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FEATURES
All grades 14-bit monotonic over the full temperature range
Low cost, 14-bit upgrade for 12-bit systems
14-bit parallel load with double buffered inputs
Small 24-pin, 0.30” DIP and SOIC
Low output leakage (<20 nA) over the full temperature range
APPLICATIONS
Microprocessor-based control systems
Digital audio
Precision servo control
Control and measurement in high temperature environments
FUNCTIONAL BLOCK DIAGRAM
2
23
1
3
4
20
21
22
245
619
14-BIT DAC
DAC REGISTER
INPUT
REGISTER
14
AD7538
DB13 TO DB0 DGND
DD
V
SS
WR
CS
LDAC
AGND
I
OUT
REF
R
FB
01139-001
Figure 1.
GENERAL DESCRIPTION
The AD7538 is a 14-bit monolithic CMOS digital-to-analog
converter (DAC) that uses laser trimmed thin-film resistors to
achieve excellent linearity.
The DAC is loaded by a single 14-bit wide word using standard
chip select and memory write logic. Double buffering, which is
optional using
LDAC
, allows simultaneous updates in a system
containing multiple AD7538s.
A novel low leakage configuration enables the AD7538 to
exhibit excellent output leakage current characteristics over
the specified temperature range.
The AD7538 is manufactured using the linear-compatible
CMOS (LC
2
MOS) process. It is speed compatible with most
microprocessors and accepts TTL or CMOS logic level inputs.
PRODUCT HIGHLIGHTS
1. Guaranteed Monotonicity.
The AD7538 is guaranteed monotonic to 14-bits over the
full temperature range for all grades.
2. Low Cost.
The AD7538, with its 14-bit dynamic range, affords a low
cost solution for 12-bit system upgrades.
3. Small Package Size.
The AD7538 is packaged in a small 24-pin, 0.3" DIP and a
24-pin SOIC.
4. Low Output Leakage.
By tying V
SS
(Pin 24) to a negative voltage, it is possible to
achieve a low output leakage current at high temperatures.
5. Wide Power Supply Tolerance.
The device operates on a +12 V to +15 V V
DD
, with a ±5%
tolerance on this nominal figure. All specifications are
guaranteed over this range.
