AD5228

Rev. A | Page 17 of 20

3.50

3.40

3.41

3.42

3.43

3.44

3.45

3.46

3.47

3.48

3.49

02468

10

1

DAYS

CONSTANT BIAS WITH SUPPLY TO

RETAIN RESISTANCE SETTING

2

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.

Figure 47. Battery Consumption Measurement

AD5228

U1

GND

U2

GND

COMPONENT X

U3

GND

COMPONENT Y

GND

SW1

+

–

Figure 46. Constant Bias AD5228 for Resistance Retention