MAX660M National Semiconductor, MAX660M Datasheet - Page 8

• Manufacturer Part Number: MAX660M
• Description: DC/DC Charge Pump Converter IC
• Manufacturer: National Semiconductor

Specifications of MAX660M

• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Supply Voltage Max: 550V
• Leaded Process Compatible: No
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

www.national.com
Other Applications
A three-stage cascade circuit shown in Figure 7 generates −3V
Cascading is also possible when devices are operating in doubling mode. In Figure 8 , two devices are cascaded to generate 3V
An example of using the circuit in Figure 7 or Figure 8 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 increases the out-
put resistance and output voltage ripple.
REGULATING V
It is possible to regulate the output of the MAX660 by use of a low dropout regulator (such as LP2951). The whole converter is
depicted in Figure 9 . This converter can give a regulated output from −1.5V to −5.5V by choosing the proper resistor ratio:
where V
ref
= 1.235V.
out
FIGURE 6. Increasing Output Voltage by Cascading Devices
(Continued)
FIGURE 7. Generating −3V
FIGURE 8. Generating +3V
8
in
, from V
in
in
in
from +V
from +V
.
in
in
DS100898-8
DS100898-10
DS100898-9
in
.