CAT661_07 Datasheet, PDF (12/17 Pages) Catalyst Semiconductor – High Frequency 100mA CMOS Charge Pump, Inverter/Doubler

CAT661
BATTERY VOLTAGE SPLITTER
Positive and negative voltages that track each other can be obtained from a battery. Figure 11 shows how a 9V battery
can provide symmetrical positive and negative voltages equal to one-half the battery voltage.
BATTERY
9V
VBAT
+
3V < VBAT < 11V
1 _BOOST/FC
V+ ⁸
2
CAP+
7
OSC
3
CAT661
GND
LV ⁶
4 _CAP-
OUT ⁵
+ ^VBAT (4.5V)
2
-
VBAT
2
(-4.5V)
+
Figure 11: Battery Splitter
CASCADE OPERATION FOR HIGHER NEGATIVE VOLTAGES
The CAT661 can be cascaded as shown in figure 12 to generate more negative voltage levels. The output resistance
is approximately the sum of the individual CAT661 output resistance.
V_OUT= -N x V_IN, where N represents the number of cascaded devices.
+
C1
+VIN
8
2 _CAT661
3
"1"
+
C1N
4
5
8
2 _CAT661
3
"N"
4
5
+ ^{C2 VOUT = -NVIN}
+ ^C2
Figure 12: Cascading to Increase Output Voltage
Doc. No. MD-5003, Rev. K
12