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+/- supply frm single chip

i m doin 1 project where i need 2 supply power 2 ADC AD677 ... i need
+/- 5/12 volts..i want this all frm single chip instead of using
7805,7812,7905 & 7912.

can u help me
 
E

Eeyore

i m doin 1 project where i need 2 supply power 2 ADC AD677 ... i need
+/- 5/12 volts..i want this all frm single chip instead of using
7805,7812,7905 & 7912.

What's the big deal about using '1 chip' only ?

Graham
 
E

Eeyore

John said:
He asked for help, not asinine bullshit.

There are some single chip twin rail ICs but they're quite expensive and not
widely available. I'm trying to find out the underlying reason for the question
so as to be able to give a decent answer.

Graham
 
P

PeteS

Eeyore said:
There are some single chip twin rail ICs but they're quite expensive and not
widely available. I'm trying to find out the underlying reason for the question
so as to be able to give a decent answer.

Graham

What's Vin?

Cheers

PeteS
 
J

John Fields

There are some single chip twin rail ICs but they're quite expensive and not
widely available. I'm trying to find out the underlying reason for the question
so as to be able to give a decent answer.

---
The big deal is, that's what he wants, and a decent answer, you rude
piece of shit, might have been: "I don't think what you want is
available, but there are some single chip twin rail ICs which are
quite expensive and not widely available. Is there any reason why
you can't use conventional supplies?
 
E

Eeyore

John said:
---
The big deal is, that's what he wants, and a decent answer, you rude
piece of shit, might have been: "I don't think what you want is
available, but there are some single chip twin rail ICs which are
quite expensive and not widely available. Is there any reason why
you can't use conventional supplies?

Still doesn't answer why he's so keen t use a single chip though. Really also need
to know what the proposed power source is. As in is it necessasry to creat a 'false
ground'.

To be honest *any* further information at all would be useful.

Got out the wrong side of bad today did you btw ?

Graham

p.s. what's your feeling about the terror con being foisted on the public ?
 
C

Chris

i m doin 1 project where i need 2 supply power 2 ADC AD677 ... i need
+/- 5/12 volts..i want this all frm single chip instead of using
7805,7812,7905 & 7912.

can u help me

In order to get a more helpful answer, you have to tell what you've got
as an input voltage, and how much power you need for the other stuff.

I'm also wondering where your requirement for -5VDC is coming from --
the AD677 only requires a +5 for logic and a +/-12V for the analog
side.

Apart from all that, no single IC exists that can do what you want.
Linear regulators are cheap and efficient -- splurge a little. But if
you want maximum simplicity or absolute minimum space, try purchasing a
small AC-to-DC converter which will give you the three voltages.

And please hold off on the text lingo unless you're kidnapped and are
being confined in a car trunk. It gives the impression you can't even
be bothered to express yourself clearly. That's not a good impression
to give if you're asking for someone to craft a ldetailed, cogent
answer.

Good luck
Chris
 
Vin is 20 V...and i hv been told 2 use a single chip...i can use the
above mentioned chips..but i hv 2 use a single chip which is a cheap 1
too...
 
J

John Fields

Vin is 20 V...and i hv been told 2 use a single chip...i can use the
above mentioned chips..but i hv 2 use a single chip which is a cheap 1
too...
 
E

Eeyore

Vin is 20 V..

AC or DC ? With or without centre tap ?
.and i hv been told 2 use a single chip...i can use the
above mentioned chips..but i hv 2 use a single chip which is a cheap 1
too...

There is no cheap single chip solution to your problem I'm afraid.

Please answer the above about the AC or DC input too.

Graahm
 
C

Chris

Vin is 20 V...and i hv been told 2 use a single chip...i can use the
above mentioned chips..but i hv 2 use a single chip which is a cheap 1
too...

The only way you're going to get from a +20V to +5V and +/-12V outputs
with one component is with a DC-to-DC converter.

Look at this from Jameco:

http://tinyurl.com/km54w

Their P/N 217648CM is a MeanWell (and I'm sure you do) DC-to-DC
converter with triple output. This is a rather expensive one part
solution to your problem.

If you want cheap, you'll have to consider going with more than one
component. For a low current requirement, I'd think the lowest cost
solution *is* a 7812 and 7805, with a small switcher to convert the
+20V to -12V.

If you want more help, you'll also have to mention your total power
requirements for each power source (i.e. how much current do you need?)

Good luck
Chris
 
T

Tim Auton

Vin is 20 V...and i hv been told 2 use a single chip...i can use the
above mentioned chips..but i hv 2 use a single chip which is a cheap 1
too...

y u hv 2 us jst 1 chp chp? :(
btw ur 4 7xxx chps wnt wrk - u nd n nvrtr 2 2 gt -V frm +V.

u cn lk @ Mxm. thy hv mltpl otpt dc-dc chps. Mxm cn smtms b 2 hrd 2 by
frm if u r nt v v bg cmpny.

http://www.maxim-ic.com/products/power/dc_dc_switchers/


Tim, getting down with the kids.
 
T

Tim Auton

Chris said:
Tim Auton wrote: [snip!]
y u hv 2 us jst 1 chp chp? :(
btw ur 4 7xxx chps wnt wrk - u nd n nvrtr 2 2 gt -V frm +V.

u cn lk @ Mxm. thy hv mltpl otpt dc-dc chps. Mxm cn smtms b 2 hrd 2 by
frm if u r nt v v bg cmpny.

http://www.maxim-ic.com/products/power/dc_dc_switchers/


Tim, getting down with the kids.

Mad props, Tim. U got skillz. ;-)

Simply pull the waitband of your trousers half-way down your arse-cheeks
and typing that way will come naturally to you too. I think the nerves
corresponding to the vowels must be located at the top of the gluteus
maximums and sensitive to cold.


Tim
 
E

Eeyore

Jamie said:
you need a DC-DC converter chip with +&- out..
look at mouser, Digikey etc...
they have Dual output types

He wants dual-dual though !

Graham
 
J

Jamie

i m doin 1 project where i need 2 supply power 2 ADC AD677 ... i need
+/- 5/12 volts..i want this all frm single chip instead of using
7805,7812,7905 & 7912.

can u help me
you need a DC-DC converter chip with +&- out..
look at mouser, Digikey etc...
they have Dual output types
 
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