AD5334BRU Analog Devices Inc, AD5334BRU Datasheet - Page 18

• Manufacturer Part Number: AD5334BRU
• Description: IC DAC 8BIT QUAD VOUT 24-TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD5334BRU

• Rohs Status: RoHS non-compliant
• Settling Time: 6µs
• Number Of Bits: 8
• Data Interface: Parallel
• Number Of Converters: 4
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 4.5mW
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP

AD5334/AD5335/AD5336/AD5344
Coarse and Fine Adjustment Using the AD5334/AD5335/
AD5336/AD5344
Two of the DACs in the AD5334/AD5335/AD5336/AD5344 can
be paired together to form a coarse and fine adjustment function,
as shown in Figure 39. As with the window comparator previ-
ously described, the description will refer to DACs A, and B and
the reference connections will depend on the actual device used.
DAC A is used to provide the coarse adjustment while DAC B
provides the fine adjustment. Varying the ratio of R1 and R2 will
change the relative effect of the coarse and fine adjustments. With
the resistor values shown the output amplifier has unity gain for
the DAC A output, so the output range is zero to (V
For DAC B the amplifier has a gain of 7.6 × 10
a range equal to 2 LSBs of DAC A.
The circuit is shown with a 2.5 V reference, but reference volt-
ages up to V
rail-to-rail output swing.
EXT
REF
AD780/REF192
WITH V
GND
V
IN
V
DD
OUT
= 5V
Figure 39. Coarse and Fine Adjustment
DD
may be used. The op amps indicated will allow a
0.1 F
0.1 F
V
V
AD5336/AD5344
REF
REF
10 F
A
B
V
DD
GND
V
DD
= 5V
V
V
OUT
OUT
51.2k
A
B
R3
51.2k
390
R1
R2
–3
390
R4
, giving DAC B
REF
5V
– 1 LSB).
V
OUT
–18–
Power Supply Bypassing and Grounding
In any circuit where accuracy is important, careful consideration
of the power supply and ground return layout helps to ensure
the rated performance. The printed circuit board on which the
AD5334/AD5335/AD5336/AD5344 is mounted should be
designed so that the analog and digital sections are separated,
and confined to certain areas of the board. If the device is in a
system where multiple devices require an AGND-to-DGND
connection, the connection should be made at one point only.
The star ground point should be established as closely as pos-
sible to the device. The AD5334/AD5335/AD5336/AD5344
should have ample supply bypassing of 10 µF in parallel with
0.1 µF on the supply located as close to the package as possible,
ideally right up against the device. The 10 µF capacitors are the
tantalum bead type. The 0.1 µF capacitor should have low
Effective Series Resistance (ESR) and Effective Series Inductance
(ESI), like the common ceramic types that provide a low imped-
ance path to ground at high frequencies to handle transient
currents due to internal logic switching.
The power supply lines of the device should use as large a trace
as possible to provide low impedance paths and reduce the
effects of glitches on the power supply line. Fast switching sig-
nals such as clocks should be shielded with digital ground to
avoid radiating noise to other parts of the board, and should
never be run near the reference inputs. Avoid crossover of digital
and analog signals. Traces on opposite sides of the board should
run at right angles to each other. This reduces the effects of
feedthrough through the board. A microstrip technique is by
far the best, but not always possible with a double-sided board.
In this technique, the component side of the board is dedicated
to ground plane while signal traces are placed on the solder side.
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