difference b/w a LDO and a DC-DC converter

[pmm]

hello
may be this question is silly but i want to main difference between a
LDO and a DC-DC converter
thanks in advance
PMM

 

[John Popelish]

pmm wrote:

hello
may be this question is silly but i want to main difference between a
LDO and a DC-DC converter
thanks in advance
PMM

An LDO (low drop out regulator) is a form of linear series regulator,
and like all linear series regulators, it wastes any excess voltage
leaving only the desired output voltage. It is called low drop out,
because it is capable of wasting a very small voltage, if that is what
is required, where most linear series regulators require that there be
at least 1.5 volts excess for them to waste in order to provide good
regulation.

A DC to DC converter is a circuit that creates a regulated (and
usually isolated) DC output voltage when it is powered from a DC
source. They convert the DC to AC, and use switching regulator
techniques to waste as little energy as possible as this AC is
converter back to some new DC voltage. Switching regulators are
always more complicated than linear regulators because they must
contain energy storage elements (inductors and capacitors) that are
used to filter the pulsed AC back to DC.

Here are links to tutorials on regulators.
Linear series regulators:
http://www.national.com/appinfo/power/files/f4.pdf
Switching regulators:
http://www.national.com/appinfo/power/files/f5.pdf
--
John Popelish