Datasheet

AD5227
Rev. B | Page 14 of 16
3.50
3.40
3.41
3.42
3.43
3.44
3.45
3.46
3.47
3.48
3.49
02468101
04419-0-041
DAYS
BATTERY VOLTAGE (V)
CONSTANT BIAS WITH SUPPLY TO
RETAIN RESISTANCE SETTING
2
T
A
= 25°C
Users who consider EEMEM potentiometers but cannot justify
the additional cost and programming for their designs can con-
sider constantly biasing the AD5227 with the supply to retain
the resistance setting as shown in Figure 38. The AD5227 is
designed specifically with low power to allow power conservation
even in battery-operated systems. As shown in Figure 39, a
similar low power digital potentiometer is biased with a 3.4 V
450 mA/hour Li-Ion cell phone battery. The measurement shows
that the device drains negligible power. Constantly biasing the
potentiometer is a practical approach because most portable
devices do not require detachable batteries for charging.
Although the resistance setting of the AD5227 is lost when the
battery needs to be replaced, this event occurs so infrequently
that the inconvenience is minimal for most applications.
Figure 39. Battery Consumption Measurement
04419-0-040
V
DD
AD5227
U1
GND
V
DD
U2
GND
COMPONENT X
V
DD
U3
GND
COMPONENT Y
GND
V
DD
BATTERY OR
SYSTEM POWER
SW1
+
–
Figure 38. Constant Bias AD5227 for Resistance Retention