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Altera_Forum's avatar
Altera_Forum
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19 years ago

Power supply supervisor

I se the referense design to Nios2 Cyclone2 board have an voltage supervisor on the 5V 3.3V and 1.2V, and as I understand the reset go to the DEV_CLRn. On other design I don't se a voltage supervisor. What is the point of having it there.

Altera advice the following:

- When starting up the power supply the voltage sould rising stright up to the desired voltage without overshoot and undershoot. (Think the last things are right)

- The voltage to the IO(3.3V) og CORE(1.2V) should rise within 100ms

If I follow this, is it then any need for an supervisor? After the power have got to the desire voltage, souldn't it be stable as long as power is coupled to the circuit board? The only reason I se the need for an supervisor is if someone pull out and in the power to te circuit board wery fast.

Alter say nothing about that.

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    19 years ago

    You may need a power supervisor, if you plan to place many chips with delicate power requirements (min-max distances between many power supply voltages and IO pin voltages to the same chip) on your board may need a supervisor chip.

    Else you should follow the next instructions for simple power solutions:

    http://www.altera.com/support/devices/vend...ow-vendors.html (http://www.altera.com/support/devices/vendors/pow-vendors.html)

    Since the current documents do not mention Cyclone II chips yet, you should do some inprovization. Put some extra effort into the placement of power decoupling capacitors, Cyclone II chips seem to be much more sensitive for power stability than Cyclone chips.

    We use a mix of a simple power supervisor chip TLC7701 from TI and switching power regulators from NS.

    IzI