3V AND 5V SECTION (ALWAYS VOLTAGE)

 

3V AND 5V SECTION (ALWAYS VOLTAGE)

This is second section in laptop motherboard called 3v and 5v section.

This section receives adapter voltage and generate 3v to get power to SIO. This section also called ALWAYS VOLTAGE SECTION.

It has two buck convertors 3.3v and 5v and two linear regulators VREG3 AND VREG5.

If this section failed, the laptop cannot TURNON.

        

                NO                                    SIGNAL                                DESCRIPTION

               1                                        VIN                                    INPUT SUPPLY TO CHIP AND                                                                                                                MOSFET

                2                                VREG3(LDO3)                         LINEAR 3 VOLT OUTPUT

               3                                 VREG5(LDO5)                       LINEAR 5 VOLT OUTPUT

               4                                 UG & LG                                UG= UPPER MOSFET TRIGGERING

                                                                                                   LG= LOWER MOSFET TRIGGERING

               5                                3ON(EN), 5ON(EN)          INPUT TO 3V AND 5V ENABLE SIGNAL

               6                                3V ALW                                   3.3V ALWAYS VOLTAGE OUTPUT

                                                 5V ALW                                    5V ALWAYS VOLTAGE OUTPUT

               7                                PGOOD                                    POWER GOOD CONFIRMATION                                                                                                             SIGNAL POWER OK

      MOTHERBOARD POWER STAGES

There are the states of the laptop depending on the power consumption of the motherboard. You already know two states when the laptop is on and when the laptop is off.

The motherboard states are referred in character "Sx". Where the X is the number between 0 and 5.

1) S0= Working system is fully usable, All the components have their voltages.

2) S1, S2, S3 = sleep.  The laptop appears to be off; the laptop consumes less power than S0 state. The RAM has its voltage, and kept refreshed, to wake up the laptop you need only press a key, the keyboard or move the mouse.

3). S4 = HIBERNATE= The system appears to be off, and the power consumption to be reduced to the lower level, an image of RAM is kept on disk because the RAM loses its voltage, to wake the laptop you need to the press power button. 

4) S5 = shutdown.

MOTHERBOARD VOLTAGES:

There are four types of voltages in the motherboard.

ALWAYS SUPPLY (ALW or AUX or AL):

            Thes voltages are always present even the laptop is off, on one condition: the battery should be placed, or the charger plugged in, these voltages are.

                        5V DC

                        3.3V DC

The 5v and 3.3v come from VOLTAGE GENERATOR IC in the motherboard.

SUSPEND VOLTAGE (SUS_ON):

                These voltages are present in SUSPEND or SLEEP MODE (S1, S2, S3):

                                        5V DC

                                        3.3V DC

                                        RAM VOLTAGE (1.2V/1.35V/1.5V/1.8V/2.5V/3.3V)

POWER ON VOLTAGE (RUN) (S0 STATE):

        All the components have now their voltagees.

                            1.05v

                            1.8v

CPU CORE VOLTAGE:

            CPU require core voltage i.e., high current approximately 20 amp TO 30 amp.

            In the new motherboards graphic chip also integrated to CPU. So, the graphics core voltage also required. These voltages are called as GFX core voltages.

These voltages called approximately.

                    CPU CORE = 0.8V TO 1.5V/ 20AMP TO 30 AMP

                    GFX CORE = 0.8V TO 1.8V /10 AMP TO 20 AMP.

                  LAPTOP POWER SEQUENCE

The power sequence is the exchange of voltages and signals between the motherboard chips that takes place before anything appears on the screen.

The power sequence is the phase in which the motherboard prepares itself tofunction. This phase consists of sending orders to different voltage generators from some ICs and receiving confirmations, making sure the principle integrated circuits of the motherboard are functional... etc.

The power sequence should take place in a specific order and if one signal or confirmation is not sent or received this phase stops there and nothing will work.

The power sequence is used to troubleshoot desktop laptop motherboard problems by testing voltages, because the absence of some voltages indicates problems with some ICs, in some schematics the power sequence is described which makes the troubleshooting process easy, and sometimes it is not and in this case i will tell you how to track the important voltages that you need.