CBC910

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DS-72-11 Rev 5

Page 10 of 14

Preliminary

To determine the battery backup switchover hysteresis for Mode 2 operation, use Figure 7.

Figure 6: MODE 2 Resistor Selection Graph

Figure 7: Mode 2 Hysteresis as a Function of R2/R1

Battery Switchover Threshold Voltage vs. R2/R1

Ratio

0

1

2

3

4

5

6

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

1.1

R2/R1 Ratio

Trip point

Hysteresis in Battery Switchover Threshold

Voltage vs. R2/R1 Ratio

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1 1.1

R2/R1 Ratio

Hysteresis

Battery charging and backup power for 2.5 to 5.5 volt operation is selected by changing the value of R2. To

determine the battery backup switchover point, set the value of R1 to 200kΩ and choose the value of R2

according to Figure 6. For example, to set a 3.0V trip point: If R1=200 kΩ then R2 = R1 x 0.72 = 144kΩ.