Datasheet

Data Sheet AD5243/AD5248
Rev. B | Page 15 of 20
CONSTANT BIAS TO RETAIN RESISTANCE SETTING
For users who desire nonvolatility but cannot justify the addi-
tional cost of an EEMEM, the AD5243/AD5248 can be considered
low cost alternatives by maintaining a constant bias to retain the
wiper setting. The AD5243/AD5248 are designed specifically for
low power applications, allowing low power consumption even
in battery-operated systems. The graph in Figure 44 demonstrates
the power consumption from a 3.4 V, 450 mAhr Li-Ion cell phone
battery connected to the AD5243/AD5248. 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.
DAYS
BATTERY LIFE DEPLETED (%)
0
90
92
94
96
5 10 15
98
100
102
104
106
108
110
20 25 30
04109-0-019
T
A
= 25°C
Figure 44. 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 the purpose of charging.
Although the resistance setting of the AD5243/AD5248 is lost
when the battery needs replacement, such events occur rather
infrequently such that this inconvenience is justified by the
lower cost and smaller size offered by the AD5243/AD5248. If
total power is lost, the user should be provided with a means to
adjust the setting accordingly.