How is the power sequencing done when there are multiple voltage supplies?

[deepak.sibi]

Hi All,

Can any one give me a brief idea about the process of POWER SEQUENCING done when there are multiple voltage supplies on the board?

TIA.,


Deepak

 

[farhada]

Re: Power Sequencing

Power sequencing can have many different benefits/reasons.

In a multi power device, such as most of the modern ICs, the device can turn off most of it's functions when not used. This means that for example in an advanced MP3 player, all functions except the keyboard controller can be turned off during normal operations, and then when the keyboard is detected, the device will power up various parts of itself and other peripheral on the board.

Doing so in a wrong way can cause damage to the IO and internal logic of many devices, for example, if the IO is turned on before the internal core is active, there is a risk that the core receives current through the IO connections and it can damage it or put it into un-defined mode.

This is a good article that describes it here:

**broken link removed**

Cheers,
/Farhad

 

[HardwareArtisan]

Power Sequencing

Different IC have different sequencing. Please refer to device datasheet.

Usually, higher power should be on prior to lower power, for avoiding internal power bus latch-up effect, which may damage your device gradually.