please help me in chois of LDO!!!!!!!!!!!

[osha]

Please someone helps me with that point
the micro controller works with an avg of 40 mA to 100 mA (max) does the LDO produces diff current
for example when the when the microcontroller needs just 40 it will give it 40 or it produces a constant current (acts a current source) if not is it's max is 100 mA

please give me (example of this LDO)

 

[Mr_Programmer]

The LDO wont work as constant current source normally. That means if your circuit consumes 40mA the LDO will give out only 40mA.
For resources regaring LDO and standard linear voltage regulators, visit www.national.com they have a great pdf with all the basics.
Common LDOs (at least for me) are:
LP2981 from National
or
TS2951 from TaiwanSemi

Regards...

 

[vvvvv]

LDO give same quantity as request , until maximum allowed for him. It's work as constant voltage source, not constant current. You must care about only three things :
LDO output voltage equal VCC of controller
LDO maximum current greater then maximum
required for controller
LDO dissipated power :
when you are using LDO be sure, that
thermal conditions is safety, because dissipated power on LDO is : (Vi-Vout)*Imax .
Usually LDO mounting on PCB square pad with
width/length 1cmx1cm for 1Wt of dissipated power.

 

[bobcat1]

Hi read this App note from TI

On how to select and untherstand LDO

h**p://focus.ti.com/analog/docs/techdocsabstract.tsp?familyId=400&abstractName=slva207

** = tt

All the best

Bobi