AD5245 查看數據表（PDF） - Analog Devices
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AD5245 Datasheet PDF : 20 Pages
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CONSTANT BIAS TO RETAIN RESISTANCE SETTING
For users who desire nonvolatility but cannot justify the
additional cost for the EEMEM, the AD5245 can be considered
a low cost alternative by maintaining a constant bias to retain
the wiper setting. The AD5245 is designed specifically with low
power in mind, which allows low power consumption even in
battery-operated systems. Figure 42 demonstrates the power
consumption from a 3.4 V, 450 mA-hr Li-Ion cell phone battery
that is connected to the AD5245. The measurement over time
shows that the device draws approximately 1.3 µA and
consumes negligible power. Over a course of 30 days, the
battery is depleted by less than 2%, the majority of which is due
to the intrinsic leakage current of the battery itself.
110%
108%
TA = 25°C
106%
104%
102%
100%
98%
96%
94%
92%
90%
0
5
10
15
20
25
30
DAYS
Figure 42. Battery Operating Life Depletion
This demonstrates that constantly biasing the potentiometer
can be a practical approach. Most portable devices do not
require the removal of batteries for charging.
AD5245
Although the resistance setting of the AD5245 is lost when the
battery needs replacement, such events occur rather infrequently
so that this inconvenience is justified by the lower cost and
smaller size offered by the AD5245. If total power is lost, then
the user should be provided with a means to adjust the setting
accordingly.
EVALUATION BOARD
An evaluation board, along with all necessary software, is
available to program the AD5245 from any PC running
Windows® 98/2000/XP. The graphical user interface, as shown
in Figure 43, is straightforward and easy to use. More detailed
information is available in the user manual, which is provided
with the board.
Figure 43. AD5245 Evaluation Board Software
The AD5245 starts at midscale upon power-up. To increment or
decrement the resistance, the user can simply move the scroll-
bars on the left. To write a specific value, the user should use the
bit pattern in the upper screen and click the Run button. The
format of writing data to the device is shown in Table 8. To read
the data from the device, the user can simply click the Read
button. The format of the read bits is shown in Table 9.
Rev. B | Page 15 of 20
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