AD5254EVAL Analog Devices Inc, AD5254EVAL Datasheet - Page 23

• Manufacturer Part Number: AD5254EVAL
• Description: BOARD EVAL FOR AD5254
• Manufacturer: Analog Devices Inc
• Type: Digital Potentiometerr

Specifications of AD5254EVAL

• Contents: Evaluation Board
• For Use With/related Products: AD5254
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

TERMINAL VOLTAGE OPERATION RANGE
The AD5253/AD5254 are designed with internal ESD diodes
for protection; these diodes also set the boundaries for the
terminal operating voltages. Positive signals present on
Terminal A, Terminal B, or Terminal W that exceed V
clamped by the forward-biased diode. Similarly, negative signals
on Terminal A, Terminal B, or Terminal W that are more
negative than V
users should not operate V
the voltage across V
polarity constraint.
2
Figure 38. Four Devices with AD1 and AD0 of 00
2 × 4
DECODER
2 × 4
DECODER
2 × 4
DECODER
2 × 4
DECODER
SS
are also clamped (see Figure 39). In practice,
DD
to V
4
4
4
4
AB
SS
, but V
, V
WA
, and V
N1
N2
AB
P4
R1
R2
X
, V
R3
P3
R4
X
+5V
WA
X
+5V
X
+5V
+5V
WB
, and V
P2
to be higher than
Y
P2
N3
Y
+5
× 4
R3
Y
× 4
× 4
× 4
Y
WB
have no
AD1
AD0
DD
AD1
AD0
AD1
AD0
AD1
AD0
are
Rev. B | Page 23 of 32
POWER-UP AND POWER-DOWN SEQUENCES
Because the ESD protection diodes limit the voltage compliance
at Terminal A, Terminal B, and Terminal W (Figure 39), it is
important to power V
these terminals. Otherwise, the diodes are forward biased such
that V
user’s circuit. Similarly, V
The ideal power-up sequence is in the following order: GND,
V
V
they are powered after V
LAYOUT AND POWER SUPPLY BIASING
It is always a good practice to employ a compact, minimum
lead-length layout design. The leads to the input should be as
direct as possible, with a minimum conductor length. Ground
paths should have low resistance and low inductance.
Similarly, it is also good practice to bypass the power supplies
with quality capacitors. Low equivalent series resistance (ESR)
1 μF to 10 μF tantalum or electrolytic capacitors should be
applied at the supplies to minimize any transient disturbance
and filter low frequency ripple. Figure 40 illustrates the basic
supply-bypassing configuration for the AD5253/AD5254.
The ground pin of the AD5253/AD5254 is used primarily as a
digital ground reference. To minimize the digital ground
bounce, the AD5253/AD5254 ground terminal should be joined
remotely to the common ground (see Figure 40).
DD
A
, V
, V
B
DD
, V
SS
Figure 39. Maximum Terminal Voltages Set by V
/V
, digital inputs, and V
W
V
V
SS
DD
, and the digital inputs is not important, as long as
SS
Figure 40. Power Supply-Bypassing Configuration
are powered unintentionally and may affect the
C3
C4
10μF
10μF
C1
C2
DD
0.1μF
0.1μF
/V
DD
DD
SS
/V
/V
before applying any voltage to
SS
A
SS
/V
.
should be powered down last.
AD5253/AD5254
V
V
B
DD
SS
/V
W
. The order of powering
AD5253/AD5254
GND
V
A
W
B
V
DD
SS
DD
and V
SS