Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
This one is not as bad as you think. Since the nmos is acting as a source follower, it naturally has very low impedance and is easier than pmos pass device to compensate. It's also very strong compared to pmos for a given size so the dropouts can be quite small, even at 1A!
In general, the output stage of your error amp must be supplied by the high voltage of the pump, and you should expect to pump (at worst case) a few Vth above Vin when Vin is dropping down to almost Vout. This is pretty simple in that it can be easily generated with almost any type of pump. In practice, the tricky parts will be
1) The pump capacitors are a big space-waster, so don't build this one in an expensive process!
2) Charge pumps are notoriously inefficient, so although it is simple to generate the required voltage, it is not simple to generate it efficiently.
Other than those two, this is a very good way to make a high $$ product. (comparatively speaking, of course).
Here are some papers on pumps - the error amp should be trivial (fold it!@).
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
