[SI-LIST] Re: Wide input range LDO

Greetings Adeel,

Take a look at Toko's (http://www.toko.com/) offering which includes many LDO 
SOT23 devices similar to what you are describing.  I haven't done an extensive 
search for your device, but some such as the TK113 accept up to a 16V input 
voltage.  I assume you're looking for a 250 mA rated part and are operating 
far below that current level.  Many of Toko's parts have on/off control and 
very low quiescent current.

I don't think this is the case, but if your application requires a very wide 
range of input voltage, such as trying to live as long as possible as a 
battery dies from +13.5V to +3V, look for a 70% to 90% efficient switching 
regulator.  That way the "drop-out voltage" of the switcher less than the 
output regulation voltage, and the part won't overheat at high voltages.  TI & 
Linear Technology offer this type of converter.

Best Regards,
Bryce 
bryce DOT bolton@patents2products DOT com

>===== Original Message From weirsi@xxxxxxxxxx =====
>Adeel, an LDO is by definition a linear device and the current at the input
>is always equal or greater than the current at the output.  Kris is
>right.  You need to change your specification, or buy lots of Freon.
>
>Steve.
>At 05:18 PM 5/24/2005 +0500, Adeel Malik wrote:
>>Hi Kris,
>>                 Thanks for the feedback. In fact the 250mA current
>>output requirement is  not at 12 Volt input. I needed an extension of
>>MCP1701 or TC55 device that can accept the nominal voltgae of 12 volts
>>(rather than 10 volts as is the case with microchip device) keeping all
>>other specs (package,Pin numbering .... etc ) the same.
>>
>>Adeel.
>>
>>-----Original Message-----
>>From: Kris Verbeeck [mailto:krisverbeeck@xxxxxxxxx]
>>Sent: Tuesday, May 24, 2005 2:49 PM
>>To: adeelmk@xxxxxxxxxxx
>>Subject: Re: [SI-LIST] Wide input range LDO
>>
>>Hi Malik,
>>
>>I hope you don't mind me saying, but I'm afraid you're
>>not going to find what you're looking for. Simple
>>calculation (7V * 0.25 = 1.75) that you plan to burn
>>1.75W in a tiny SOT-23. I don't think it's gonna
>>happen.
>>
>>Anyways, here's a link with good quality LDO's you may
>>want to check out. ->
>>http://www.linear-tech.com/pc/categoryProducts.do
>>
>>Hoping others will prove me wrong,
>>
>>Kris Verbeeck.
>>
>>--- Adeel Malik <adeelmk@xxxxxxxxxxx> wrote:
>> > Hi All,
>> >             In our low Power-Impedance design we
>> > require an LDO that can
>> > accept 12V input voltage for its stable 5 volt
>> > output in 3-Pin SOT-23 or
>> > SOT-89 package. The output current requirement is at
>> > least 250mA with
>> > the quiescent current consumption of about 2uA or
>> > less.
>> > I have searched the web and was able to find TC55
>> > and MCP1701 from
>> > Microchip but the only problem is that their input
>> > voltage is limited to
>> > 10Volts. Can someone help me finding the aforesaid
>> > LDO.
>> >
>> > Regards,
>> > Adeel Malik
>> >
>> >
>> >
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