ncp1400 question

[blackjames]

hi, i need a voltage regulator with 10V output. in the past i have offset the ground pin on a 78L05 but i needed two nine volt batteries in series to get enough voltage. can i use a NCP1400 and offset the ground pin so i get 10 volts out?

[mariush]

why don't you just go with a dc-dc converter?

34063 chips are cheap as chips (yeah, bit of wordplay, lame).

[blackjames]

i only need to draw 50mA or less and the dc to dc conversion circuit needs to be compact

[ve7xen]

LM317? 7810? Most adjustable LDOs on the market... I'm not sure what trouble you're having here, this is a problem for which solutions abound and I'd think you'd be having more trouble choosing one than finding one.

[blackjames]

i want to get rid of two heavy expensive nine volt batteries and replace it with one or two AA's

[ve7xen]

Then you will need some form of DC/DC converter. Standard regulators can only drop voltage, they can't boost it as you need to get 10V out of 1.5-3V input.

Most solutions will not be much smaller than a pair of 9V batteries though. I'd second the 34063 or suggest going to eBay for a One Hung Low converter board, e.g. something like this http://www.ebay.com/itm/DC-DC-Lithium-Battery-Boost-Module-2-6V-to-3-3-9V-2A-Power-Supply-Converter-/290832547697?pt=LH_DefaultDomain_0&hash=item43b6f87f71

Doing it on 1AA is a bit trickier and you'll probably have to design something custom and/or pay more. 2xAA should be pretty easy with off the shelf stuff like that though.

[mariush]

http://uk.farnell.com/microchip/mcp1804t-a002i-ot/ic-ldo-10v-150ma-5sot23/dp/1825009
http://uk.farnell.com/national-semiconductor/lm2940imp-10-nopb/ic-ldo-reg/dp/1685531
http://uk.farnell.com/national-semiconductor/lm2940s-10-nopb/ic-ldo-reg/dp/1685528
http://uk.farnell.com/national-semiconductor/lm2937imp-10-nopb/ic-v-reg-linear-10v-smd/dp/1469068

if you want fixed versions.. i gather you're from australia so just use element14 i guess.

but you can use any adjustable regulator that can handle more than 10v input to produce 10v, you only need two extra resistors besides the IC.

Oh.. and it would be kinda dumb to use two 9v batteries to do 10v 50mA - not only the 9v batteries have very little capacity, but the linear regulator will just waste the difference of volts between 18v and 10v as heat.. so if you pull 50mA, you basically waste 8v x 0.05 =  0.4 watts, and you waste half of the life of the batteries, maybe even more.
If you have room for two 9v batteries you should have room for a switching regulator, if not on the board, on a small pcb by the battery holder. 2-3 AA batteries should last much longer than 2 9v batteries.

Tps6744 (or something similar) would also be a good choice, boost to 12v from whatever you have (at least 2.7v), then use a cheapo ldo to go down to 10v: http://uk.farnell.com/texas-instruments/tps6734idr/ic-boost-converter-8-soic/dp/1575732
 
(you posted while i was writing this... yeah, search for boost regulators, adjustable versions will do. If you want very clear output voltage, just configure the boost regulator to do 10.4v and then use a low drop regulator to go down to 10v)

What kind of controller/component needs 10v though?

[blackjames]

Im building a handheld device that outputs 0 to 10volts or 0 to 20 mA. It will be used to test variable ac drives and other industrial equipment. I have already made 2 with a simples design but its not great having 2 nine volt batteries in each

[mariush]

Dave's usb power supply outputs 0-15v  , 0-1A , see how he did it here:

http://eevblog.com/files/uSupplyUSBrevB.pdf

Remove the usb functionality, the isolation transformer and the battery charger if you plan to use 2-3 aa batteries instead of a li-ion pack and if you want to go cheap, replace the 3080 with something else.
Problem solved.

[blackjames]

Good idea. Ive started to alter his design to my preferences