Hello everyone..

I am stuck with the power supply sequencing part in my design.
How to design a circuit for power sequencing a microprocessor using discrete components...??? and also how to achieve the timings between different power supply rails application...??
Can anyone help me out ....

 

You are either above my level of knowledge, or I am just plain confused by what you are asking.

What type of sequencing do you need for the uC?

And if you are using DC, why do you need timing differences between the rails? They should always be "there".

 

this paper may help

Sequencing Power Supplies in​

Multiple Voltage Rail Environments
http://focus.ti.com/lit/ml/slup228/slup228.pdf

 

A chip may require different voltages for the I/O padring and the processor core. It is not uncommon to have a requirement that the I/O padring be powered up and stable for some period of time before the core is powered up. Doing this with discrete components is foolish, in my opinion, given that many voltage regulators come with an enable input.

I have an XMOS eval board that uses a FAN2558S33X to generate 3.3V from 5V. The 3.3V Power Good output, with a 10 K pullup to +5V goes directly to the enable input of an SC4626A that generates 1.0V from 5V.

Simple -- Elegant

 

Ah. I was think more along the lines of phase matching. Thats why I was questioning the DC.

I see now.