About the internal supply for DC-DC?

[newhand]

Hi guys:
I am just getting involved in a DC-DC project,since the input voltage is high than 15V and our process is about 5v cmos process,so I need to design a inner regulator as a supply for the circuit.
But for the regulator,I don't know how to decide its specification,such as ,bandwidth,the value of output cap,startup time?
Has someone ever met the same difficulty as me?

 

[harrytrinh]

It is not that difficult. Just do a regulator that has output less than 5V to satisfy process. Also the regulator need to have enough current to supply whole thing inside. If you decided output voltage and output current capacity for regulator then designing that regulator will be easy. You can you band gap structure to get better TC. Don't forget start up for the regulator because it is very important.

 

[newhand]

hi harrytrinh:
I know I need a regulator(<5v output) as my internal supply for the inner circuit.But have you ever considered that how much the bandwidth of the regulator,and how big is the cap you will put at the output of the regulator,and you should guarantee that when switching,the undershoot and overshoot will be acceptable.So how do you deal with these issues.?

 

[mists]

sorry, another question, your process is 5v cmos process, then what process that you use to design regulator which should have 15v input, thanks!

 

[newhand]

5v cmos but some high voltage included in this process