Preliminary
EnerChip CC CBC3105
Mode 2 Operation
Figure 7 shows the circuitry for user-selectable switchover threshold to a value between 2.5 and 5.0 volts. Use
Figure 8 to determine the value of R1. To determine the amount of hysteresis from the EnerChip switchover
threshold, use Figure 9.
Figure 7: CBC3105 Typical Circuit for Mode 2 Operation
EnerChip charging and backup power switchover threshold for 2.5 to 5.5 volt operation is selected by changing
the value of R2 (see Figure 7). To determine the backup switchover point, set the value of R1 to 200kΩ and
choose the value of R2 according to Figure 8. For example, to set a 3.0V trip point: If R1=200 kΩ then R2 = R1
x 0.72 = 144kΩ. Figure 7 shows a Mode 2 circuit with standard value resistors of 200kΩ and 143kΩ.
To determine the backup switchover hysteresis for Mode 2 operation, use Figure 9.
Battery Switchover Threshold Voltage vs. R2/R1
Ratio
6
Switchover Threshold Voltage (Volts)
5
4
3
2
1
0
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
0.09
0.08
0.07
Hysteresis (Volts)
0.06
0.05
0.04
0.03
0.02
0.01
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
R2/R1 Ratio
1
1.1
Hysteresis
Figure 8: Mode 2 Resistor Selection Graph
Figure 9: Mode 2 Hysteresis as a Function of R2/R1
DS-72-21 Rev E
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