12 V regulator

[Ron Schroeder]

Hi,

I would try a LT1086.  It is a low dropout version of the LM317.  If set to
12V out, the output will regulate with an input down to about 12.4V and
then will be slightly less than 1/2V below the input all the way down to
about 2 volts.

Ron



At 01:33 PM 12/3/01 -0500, you wrote:
>Bob
>
>Let me re-state my requirement to clear up the request.
>
>The regulator needs to supply an Input voltage of 12 Volts (+/- 15%) to the
>time delay relay.
>And must be good for a normal 12 volt auto configuration, and also a 16 volt
>racing battery application.
>
>So lets just say the regulator should be able to do the following:
>
>Input 12 - 18 V
>Ouput 12 Volts (1ma to 500ma)
>
>If the input swings below 12 (ex 10.5) then it is ok for the output to also
>swing to
>10.5.  This is in case the 12V car battery goes a little low due to some
>problem.
>
>Steve
>
>-----Original Message-----
>From: rr [mailto:RRauscher at nni.com]
>Sent: Monday, December 03, 2001 12:22 PM
>To: diy_efi at diy-efi.org
>Subject: Re: 12 V regulator
>
>
>
>With the input voltage requirements spanning above and below
>the output voltage requirements, the only regulator that will
>operate correctly is a switching buck-boost combination.
>
>BobR.
>
>
>Steve.Flanagan at VerizonWireless.com wrote:
>
>> I have a requirement for 12 V regulation (+/- 15% or a range of 10.2 to
>13.8
>> volts).
>>
>> My application is driving several 12V time delay relays (TDRs) and I am
>> building it to work in a drag car that can be powered with 12v +
>Alternator
>> or a 16V system.  Keep in mind that with the 16V system, the battery
>charger
>> can put over 18V's.
>>
>> The TDRs pull as low as 1 ma each when in the off state, and as high as
>200
>> ma each when the relay is triggered.   So lets just say my requirements
>for
>> a regulator are:
>>
>> Input Voltage:  10v to 20v
>> Output Voltage: 12v (+/- 15%)
>> Output Current: 1mA to 500mA
>>
>> I tried to use a 12V regulator purchased from Digikey just as a test and
>it
>> seems to crap out at the lower current levels (I don't have the part
>number
>> handy, its at home, and this was a project I was working on over a year
>ago,
>> something just stirred up my memory that I never was able to resolve this.
>> Originally I was not aware of the lower current levels, so the regulator I
>> purchased worked in the 100ma range, but not at lower (1ma) range.
>>
>> Could someone recommend a very reliable 12V regulator that I can use to
>meet
>> my needs.
>>
>> As a work around I built my own regulator with a 12 V zener, resistor and
>> 2n2222 transistor that seems to work, however, I am concerned about the
>> reliability and heat issues with the 2n2222.
>>
>> Thanks,
>>
>> Steve F
>>
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Ron Schroeder
WD8CDH
E. E. S.
wd8cdh at bnl.gov
rjs at bnl.gov
631 344-4561 Day
631 286-5677 Nite
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