AVR-Chat

On Fri, 12 Oct 2007 19:39:20 -0300  you ("Alexandre Guimaraes"
<listas@logikos.com.br>) wrote:

Seems risky to me. Its going to depend a lot on the nature of this wildly
fluctuating supply and short term changes in voltage. Is the cost of a $0.50
regulator with 20 volt zener on the input via a resistor really excessive?

> 
>Hi,
> 
>	I have an application where a simple and cheap zener regulator with
>emitter follower would be my best ( cheap) option for powering a Atmega168
>with the AD converter using the internal 1.1 volts reference. As the input
>voltage range is way to big, from about 5 volts up to 40 volts, the
>regulation will not be too good because the zener current will vary too
>much.
> 
>	I did not find any references if I will get into trouble varying the
>supply at the AVR in the range of 3 to 5 volts. Does anyone have references
>or opnions about this ? Would the AD suffer from those variations in supply
>voltage even using the internal bandgap as a reference ? I just need 8 bit's
>out of the AD...
> 
>	I would appreciate any insight. I always try to make the power
>supply as stable as possible and letting it out to the microcontroller with
>such a big variation feels really weird to me... But I looked around all I
>could and did not find anywhere saying that I could not do it with a micro
>that is specified for this full range !
> 
>	Thanks in advance...
> 
>Best regards,
>Alexandre Guimaraes
>
>
>
> 
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>
>
>

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Ralph Hilton
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