How can i make voltages?

[tomato]

Hi,all

I wanna make voltages to provide a regulated supply for core circuit

What can i use in A and B block?

help me !!

 

[pouchito]

not clear?
can you explain?
you mean you want to use a single power op amp ?
use LM358

 

[Old Nick]

If you want to make the voltages off chip then obviously, you can just use voltage regs.

To create them on chip, you'll need to design such circuits yourself. A quick search on google should give you plenty of schematics, you'll just need to sim them to find out if the'll do what you need.

You'll need to have a very clear idea of the amount of current these will have to supply, and (obviously) design for that.

 

[hr_rezaee]

Hi
If you want to design it as on chip part, use LDO.
regards

 

[tomato]

I am sorry to confuse. I want to design on chip.
If i design as Fig A and B without external, is it OK?

Q1. If i use the Fig.B, what kind of type pass transistor of LDO is used as vss power?
I have to use nmos for sinking current?

 

[hr_rezaee]

Hi
you must explain more.
regards

 

[yaodao]

maybe you should give some parameters just like input voltage,output voltage and output current,so could anyone help you.

 

[tomato]

pls refer to the attached file..

Input vef. = 3.5V
Output vtg = 1V

loding current of output is about 100mA.

 

[tomato]

One more question about LDO..

Vref terminal of the Fig. A is on '-' , and B is not.
what's different?

thanks..

 

[mists]

1 is right, 2 wrong, it is positive feedback

 

[hr_rezaee]

Hi
yes, Fig A is true.
As I know you must buffer output.
(current can effects on thid circuit)
If you use buffer, it can sink and source current and there will be no problem.
regards

 

[tomato]

thanks...all
I have one more question
For example,
Vout=Vref(1+R1/R2)
Vref=3.5 ,1.5V and Vout to make is 1V as shown in the 2nd circuit.
Vout is always over Vref. how to make?

and,
If i use the 2nd circuit, what kind of type pass transistor of LDO is used as vss power?
I have to use nmos pass tr. for sinking current?

thanks for your help!!

 

[tomato]

Hi
yes, Fig A is true.
As I know you must buffer output.
(current can effects on thid circuit)
If you use buffer, it can sink and source current and there will be no problem.
regards

thanks..jr_rezaee

can u explain about the buffer output? or give me a related paper?

 

[hr_rezaee]

Hi