plz any pdf file explain the laptop power sequence

[bembeno]

plz any pdf file explain the laptop power sequence

[mon2]

Re: plz any pdf file explain the laptop power sequence

Please post the specifics for your laptop. Which make / model / logic board (if known) ?

[bembeno]

Re: plz any pdf file explain the laptop power sequence

i mean in public if possible

[mon2]

Re: plz any pdf file explain the laptop power sequence

I am not sure that I understand your question but let me try.

Each laptop is based on a main (external) power adapter as the primary voltage source. This power supply is often 19V or higher. This could be a simple coax (round barrel) jack that simply outputs the 19V or higher. Or this could be a more modern USB Type C power delivery (PD) adapter.

If PD style, the voltage rail supplied by default is usually 5 volts. The laptop has a USB controller inside the logic board and is consider the SINK. While the outside PD adapter is the SOURCE.

The SOURCE and SINK communicate over the CC1 and CC2 lines using a special handshake. They exchange power (voltage and current) packets called contracts.

Once the logic board receives a list of the power contracts, the logic board will then select the best choice to power itself. On the Apple modern units with Type C, this typically means 20V @ 3A or higher current.

Internally on the logic board, this high voltage is stepped down to lower voltages through BUCK convertors which are switching power supplies for the best efficiencies (so they do not heat up during use). Each such switching power supply has a power controller + coil + capacitors to build this voltage rail.

Often these voltage rails have current sense support to monitor how much of a voltage drop occurs on each rail. If the voltage drop is too much, the power rail will shut down.

A faulty cap can cause this event (hence the name of this user forum!).

Once the multiple voltages are deemed stable, a reset circuit is released and the CPU then proceeds to boot and normally.

It will be best if you post details of what it is that you are attempting to service. Perhaps details of the schematic are available to assist you.

A good start is to study the voltages on EACH COIL with a multimeter. If you find some strange value then most likely there is damage in that area due to a damaged mosfet; damaged power controller or shorted cap(s).

[bembeno]

Re: plz any pdf file explain the laptop power sequence


Thank u so much

[Arshad alam4659]

Re: plz any pdf file explain the laptop power sequence

Hii everyone ...

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