LM2662M National Semiconductor, LM2662M Datasheet - Page 9

• Manufacturer Part Number: LM2662M
• Description: IC, DC/DC VOLTAGE CONVERTER, 8-SOIC
• Manufacturer: National Semiconductor

Specifications of LM2662M

• Primary Input Voltage: 5V
• No. Of Outputs: 1
• Output Current: 200mA
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +85°C
• Power Dissipation Pd: 735mW
• Supply Voltage Range: 1.5V To 5.5V
• 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 pro-
duce a greater negative voltage (as shown in Figure 5). If n is
the integer representing the number of devices cascaded, the
unloaded output voltage V
resistance is equal to the weighted sum of each individual
device:
A three-stage cascade circuit shown in Figure 6 generates
−3V
in
, from V
in
.
1
, while only one output capacitor C
out
is (−nV
FIGURE 4. Lowering Output Resistance by Paralleling Devices
FIGURE 5. Increasing Output Voltage by Cascading Devices
in
). The effective output
out
is
9
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 gen-
erating +15V or −15V from a +5V input.
Note that, the number of n is practically limited since the in-
creasing of n significantly reduces the efficiency and increas-
es the output resistance and output voltage ripple.
in
.
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