AD5228 Analog Devices, Inc., AD5228 Datasheet - Page 17

• Manufacturer Part Number: AD5228
• Description: 32-position Manual Up/down Control Potentiometer
• Manufacturer: Analog Devices, Inc.

CONSTANT BIAS WITH SUPPLY TO
RETAIN RESISTANCE SETTING
Users who consider EEMEM potentiometers but cannot justify
the additional cost and programming for their designs can
consider constantly biasing the AD5228 with the supply to
retain the resistance setting as shown in Figure 46. The AD5228
is designed specifically with low power to allow power conser-
vation even in battery-operated systems. As shown in Figure 47,
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 of the
portable devices do not require detachable batteries for charging.
Although the resistance setting of the AD5228 is lost when the
battery needs to be replaced, this event occurs so infrequently
that the inconvenience is minimal for most applications.
SW1
+
–
Figure 46. Constant Bias AD5228 for Resistance Retention
U1
V
DD
AD5228
GND
GND
V
DD
U2
COMPONENT X
GND
V
DD
U3
COMPONENT Y
GND
V
DD
Rev. 0 | Page 17 of 20
3.50
3.49
3.48
3.47
3.46
3.45
3.44
3.43
3.42
3.41
3.40
0
Figure 47. Battery Consumption Measurement
2
4
DAYS
6
8
T
A
10
= 25°C
AD5228
12