[sdiy] SMD part availability, manufacture

[Seb Francis]

Ingo Debus wrote:
>
> Am 13.11.2008 um 01:31 schrieb Seb Francis:
>
>> For the power supply regulators, I've been looking at low dropout ICs 
>> and these seem pretty cool.  Am I really understanding it right that 
>> they can work with a output-input of down to like 0.2V.  This would 
>> mean only a tiny amount of heat dissipation so no need for any 
>> heatsinking.  Are there any disadvantages to these compared to 
>> standard linear regulators which need typically 2.5V output-input 
>> differential?
>>
>
> Many LDOs need a low-ESR cap at the output.
>

Like a ceramic chip capacitor in uF range I guess.

Just been reading this LT datasheet which goes into some detail about 
suitable caps..
http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1040,C1055,P1778,D3903
(page 15)

They are saying that X5R or better still X7R ceramic caps are fine.

They also say elsewhere that "Small ceramic capacitors can be used 
without the series resistance required by other regulators" which leads 
me to assume that some LDO regulators actually need a higher ESR to be 
stable.  So I guess it pays to read the datasheet!

Seb