LM2663M National Semiconductor, LM2663M Datasheet - Page 9

• Manufacturer Part Number: LM2663M
• Description: DC/DC Charge Pump Converter IC
• Manufacturer: National Semiconductor

Specifications of LM2663M

• Output Current: 200mA
• No. Of Pins: 8
• Power Dissipation Pd: 735mW
• Mounting Type: Surface Mount
• Peak Reflow Compatible (260 C): No
• Supply Voltage Max: 5.5V
• Leaded Process Compatible: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Other Applications
PARALLELING DEVICES
Any number of LM2662s (or LM2663s) can be paralleled to
reduce the output resistance. Each device must have its own
pumping capacitor C
needed as shown in Figure 4. The composite output resis-
tance is:
CASCADING DEVICES
Cascading the LM2662s (or LM2663s) is an easy way to
produce a greater negative voltage (as shown in Figure 5). If
n is the integer representing the number of devices cas-
caded, the unloaded output voltage V
effective output resistance is equal to the weighted sum of
each individual device:
1
, while only one output capacitor C
FIGURE 4. Lowering Output Resistance by Paralleling Devices
FIGURE 5. Increasing Output Voltage by Cascading Devices
out
is (−nV
in
). The
out
is
9
A three-stage cascade circuit shown in Figure 6 generates
−3V
Cascading is also possible when devices are operating in
doubling mode. In Figure 7, two devices are cascaded to
generate 3V
An example of using the circuit in Figure 6 or Figure 7 is
generating +15V or −15V from a +5V input.
Note that, the number of n is practically limited since the
increasing of n significantly reduces the efficiency and in-
creases the output resistance and output voltage ripple.
in
, from V
in
in
.
.
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