78xx regulator IC

M

marvilos

New Member

• Aug 15, 2006

• #1

hi all,

please help me.....
what the max input voltage for this ic...
is that ok if i give 48 vdc for input...?

thx's

 

RODALCO

Well-Known Member

• Aug 15, 2006

• #2

No, you will fry it.
It's max. rating is around 35 Volts dc.
Even at that voltage it needs a good sized heatsink.

What load are you expecting to draw from it ??

Have a look on Gooogle for a data sheet with exact maxima.

 

M

marvilos

New Member

• Aug 15, 2006

• #3

thx's for reply me

yes that correct i just get it's datasheet.
actually i need to convert 48 vdc to +/- 12 vdc or +/- 24 vdc with current 2 amp , is there any IC that i can use for it?

thank you

 

H

hjames

New Member

• Aug 15, 2006

• #4

You'll need a switching regulator for that. Search for "buck" regulators at www.national.com, www.linear.com, www.maxim-ic.com .Linear regulators will not work at all for that. (Or just buy a 1/2 or 1/4 brick converter and be done with it).

 

Hero999

Banned

• Aug 15, 2006

• #5

You can buy pre-built DC-DC converters to do this.

**broken link removed**

 

RODALCO

Well-Known Member

• Aug 16, 2006

• #6

As already suggested above a DC - DC converter will be your best bet.

Google for it.

If you want to draw 2 Amps at ± 12 Volts you need to dissipate 36 Volts x 2 Amps = 72 Watts !!
That is an enormous amount of heat and wasted power.

A DC - DC converter can run with efficiencies over 80%.

 

justDIY

Active Member

• Aug 16, 2006

• #7

National has a big line of "simple switchers", but most of them stop at 42 volts, which is odd ... there are some "high voltage" ones rated to 76 volts ... also check out texas instruments and dallas-maxim ... both have fairly simple chips to do the job.