voltage for spartan 3 XC3S500E

[m_kavith]

i need seperate supply for spartan 3 development board.
3.3v for vcco
2.5v for vccaux
1.2v for vccint
for vcco & Vccaux,using LM1117 Regulator. which regulator is used for 1.2v? need immediately plz any one help me.

 

[emresel]

It depends on your design.
What is your input voltage to your board? 12V?
Is there any estimation for current rating on 1v2?

 

[m_kavith]

input voltage is 5v. its a prototype board. only used for student projects.

 

[emresel]

Hi;
Since your input voltage is relatively small, may be you can use more powerfull LDO (like LM117 DPAK package)
But you should consider about the cooling necessities. As your logic core desing gets comlex, it draws more current and regulator may get hot.
Consider 1Amp@1.2V means a power dissipation on regulator aroud 3.8 Watts.
Or better way, use a simple stepdown like LM2575, and forget about cooling and that kind of problems (of course needs a little bit more PCB space bacuse of coils and other components).

Good luck