i am struggling in problem while interfacing lpc2148 and peripherals require 5v supply. when i control the circuit i used transistor to control but for reading and writing logic at Pins it difficult.
So if any IC to convert logic level between 3.3V to v and viceversa

 

Google "logic level converter".

 

Look for parts that have a Vcc range of 1.65V to 5.5V, TTL thresholds (0.8V, 2.0V), and 5V tolerant inputs.

 

Most often, it should be no problem connecting any output (only) from a 3.3 volt device to a 5 volt device input. For output (only) from the 5 volt device to the 3.3 volt device. You can use 5 volt tolerant logic or a dual supply bus tranciever.
http://www.ti.com/lit/ml/scba010/scba010.pdf
http://www.nxp.com/documents/application_note/AN240.pdf