CAT660 Datasheet, PDF (12/15 Pages) Catalyst Semiconductor – 100mA CMOS Charge Pump Inverter/Doubler

CAT660
Cascade Operation for Higher Negative Voltages
The CAT660 can be cascaded as shown in Figure 22 to generate more negative voltage levels. The output resistance is
approximately the sum of the individual CAT660 output resistance.
V_OUT = −N x V_IN, where N represents the number of cascaded devices.
+
C1
+V_IN
8
8
2
CAT660
3
“1”
2
+
C1
3
CAT660
“N”
4
5
4
C2
+
5
V_OUT = −NV_IN
C2
+
Figure 22. Cascading to Increase Output Voltage
Parallel Operation
Paralleling CAT660 devices will lower output resistance. As shown in Figure 23, each device requires its own pump
capacitor, C2, but the output reservoir capacitor is shared with all devices. The value of C2 should be increased by a factor of
N, where N is the number of devices.
The output impedance of the combined CAT660’s is:
R_OUT
(Of
“N”
CAT660Ȁs)
+
R_OUT (Of the CAT660)
N (Number of devices)
+
C1
+V_IN
8
8
2
CAT660
3
“1”
2
+
C1
3
CAT660
“N”
4
5
4
5
C2
+
Figure 23. Paralleling Devices Reduce Output Resistance
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