Battery backup

[ClueLess]

Hi All

I have a setup with 8051 micro controller and I want to provide a
battery backup so that when power fails the micro continues to work.
Only the micro needs to work and other peripherals need not.

What will be the minimum circuitry and what is the minimum voltage
required to keep this micro up?

--

Thanks for your time and attention

ClueLess

 

[Rich Grise]

On Wed, 21 May 2008 14:54:47 +0800, ClueLess wrote:

Hi All

I have a setup with 8051 micro controller and I want to provide a
battery backup so that when power fails the micro continues to work.
Only the micro needs to work and other peripherals need not.

What will be the minimum circuitry

Two diodes, for isolation.

and what is the minimum voltage
required to keep this micro up?

That depends on which model of micro - check the data sheet for
a "power down" or "sleep" mode or the like; the data sheet knows
all. ;-)

Good Luck!
Rich

 

[ClueLess]

On Wed, 21 May 2008 17:52:38 GMT, Rich Grise <rich@example.net> wrote:

Two diodes, for isolation.

Say, how do you connect them? Is one not enough?

--

Thanks for your time and attention

ClueLess

 

[Rich Grise]

On Wed, 21 May 2008 14:53:56 -0500, Lord Garth wrote:

"Rich Grise" <rich@example.net> wrote in message
On Wed, 21 May 2008 14:54:47 +0800, ClueLess wrote:

"model"
Good Luck!
Rich

The spelling police are going to get you!!!

What? How would _you_ spell "model"?
http://www.google.com/search?q=define%3Amodel

Thanks,
Rich

 

[Rich Grise]

On Thu, 22 May 2008 14:25:47 +0800, ClueLess wrote:

On Wed, 21 May 2008 17:52:38 GMT, Rich Grise <rich@example.net> wrote:

Two diodes, for isolation.

Say, how do you connect them? Is one not enough?

That depends on if you're worried about proper current-sharing; this
isn't my forte, so hopefully someone can give a more comprehensive
answer - OP asked for the "simplest", and that came to my simple mind. ;-)

Thanks,
Rich

 

[John Fields]

On Thu, 22 May 2008 19:12:39 GMT, Rich Grise <rich@example.net> wrote:

On Thu, 22 May 2008 14:25:47 +0800, ClueLess wrote:

On Wed, 21 May 2008 17:52:38 GMT, Rich Grise <rich@example.net> wrote:

Two diodes, for isolation.

Say, how do you connect them? Is one not enough?

That depends on if you're worried about proper current-sharing; this
isn't my forte, so hopefully someone can give a more comprehensive
answer - OP asked for the "simplest", and that came to my simple mind. ;-)

+--[DIODE>]--+--[<DIODE]--+
|+ | |+
[SUPPLY] [MICRO] [BAT]
| | |
+------------+------------+

The voltage from the supply should be high enough to reverse-bias the
battery-side diode.

JF

 

[Eeyore]

ClueLess wrote:

up?

Varies with manufacturer and specific model. Certainly as low as 2.7V
IIRC with some Philips (NXP) parts.

Graham

 

[ClueLess]

On Thu, 22 May 2008 14:30:49 -0500, John Fields
<jfields@austininstruments.com> wrote:

--+
|+ | |+
[SUPPLY] [MICRO] [BAT]
| | |
+------------+------------+

The voltage from the supply should be high enough to reverse-bias the

Much thanks for the response. That goes to the others too.

--

Thanks for your time and attention

ClueLess

 

[Rich Grise]

On Thu, 22 May 2008 15:03:55 -0500, Lord Garth wrote:

"Rich Grise" <rich@example.net> wrote in message
newsan.2008.05.22.19.11.10.923988@example.net...
On Wed, 21 May 2008 14:53:56 -0500, Lord Garth wrote:
"Rich Grise" <rich@example.net> wrote in message
On Wed, 21 May 2008 14:54:47 +0800, ClueLess wrote:

"model"

The spelling police are going to get you!!!

What? How would _you_ spell "model"?
http://www.google.com/search?q=define%3Amodel

Rich, that was another worker in this office screwing with my
computer when I was making a pit stop.

OK, no harm, no foul.

Cheers!
Rich