LTC1046 Linear Technology, LTC1046 Datasheet - Page 8

• Manufacturer Part Number: LTC1046
• Description: Inductorless 5V to + 5V Converter
• Manufacturer: Linear Technology

LTC1046
Battery Splitter
A common need in many systems is to obtain positive and
negative supplies from a single battery or single power
supply system. Where current requirements are small, the
circuit shown in Figure 10 is a simple solution. It provides
symmetrical positive or negative output voltages, both
8
TYPICAL
V
9V
B
3V V
10 F
C1
B
+
12V
A
PPLICATI
1
2
3
4
Figure 10. Battery Splitter
BOOST
CAP
GND
CAP
LTC1046
10 F
+
–
10 F
C1
V
+
OSC
OUT
+
V
LV
+
8
7
6
5
O
1
2
3
4
U
BOOST
CAP
GND
CAP
1
2
3
4
REQUIRED FOR V
LTC1046
BOOST
CAP
GND
CAP
S
+
–
+
LTC1046
Figure 11. Paralleling for 100mA Load Current
1046 F10
+
–
C2
10 F
V
OSC
OUT
+V
4.5V
–V
–4.5V
Figure 12. Stacking for Higher Voltage
V
LV
OUTPUT COMM0N
V
+
OSC
V
OUT
B
B
V
+
LV
/2
/2
8
7
6
5
+
B
8
7
6
5
< 6V
+
–(V
10 F
10 F
C1
+
)
+
10 F
C1
equal to one half the input voltage. The output voltages are
both referenced to Pin 3 (output common). If the input
voltage between Pin 8 and Pin 5 is less than 6V, Pin 6
should also be connected to Pin 3, as shown by the
dashed line.
Paralleling for Lower Output Resistance
Additional flexibility of the LTC1046 is shown in Figures 11
and 12. Figure 11 shows two LTC1046s connected in
parallel to provide a lower effective output resistance. If,
however, the output resistance is dominated by 1/fC1,
increasing the capacitor size (C1) or increasing the fre-
quency will be of more benefit than the paralleling
circuit shown.
Figure 12 makes use of “stacking” two LTC1046s to
provide even higher voltages. In Figure 12, a negative
voltage doubler or tripler can be achieved depending upon
how Pin 8 of the second LTC1046 is connected, as shown
schematically by the switch.
OPTIONAL SYNCHRONIZATION
1
2
3
4
CIRCUIT TO MINIMIZE RIPPLE
FOR V
BOOST
CAP
GND
CAP
1
2
3
4
LTC1046
OUT
BOOST
CAP
GND
CAP
+
–
1/4 CD4077
LTC1046
= –3V
+
–
V
OSC
OUT
V
LV
V
+
+
OSC
OUT
V
LV
8
7
6
5
+
8
7
6
5
FOR V
+
1046 F12
10 F
+
V
1046 F11
OUT
C2
20 F
OUT
V
V
OUT
+
= –2V
= –(V
+
+
)