The LTNP chip is a Linear Technology LTC3440. If you go to their site
www.linear.com and search for 3440, you will find all kind of information about it. And you can order it, or request a sample. If you request a sample, tell them that you are currently developping an external hard drive box - it should sound a bit professional because the samples are normally completely free, or they want a handling fee.
Horst