(https://displaymonk.com/)
Power Sequence Of Laptop Motherboard
April 27, 2022 by displaymonk (https://displaymonk.com/author/prasadbakare/)
Understanding the power sequence of laptop motherboards is very
important. Firstly the power sequence is the exchange of voltages and
signals between the motherboard chips.
Secondly, This happens before anything appears on the screen.
The power sequence is the phase in which the motherboard prepares
itself to function. This phase consists of sending orders to different
voltage generators from some ICs. Secondly, receiving confirmation
makes sure the principal Integrated circuits of the motherboard are
functional.
The power sequence should take place in a specific order. Secondly, if
one signal or confirmation is not sent or received then this phase stops
there and finally, nothing will work.
The power sequence is used to troubleshoot laptop motherboard
problems (https://displaymonk.com/laptop-chip-level-repair-careerguide/) by testing voltages because the absence of some voltages
indicates problems with some ICs. Also in some schematics, the power
sequence is described which makes troubleshooting easier.
Steps To Check Voltage And Signal Sequence
For Laptop Motherboard Power On Stage
The steps are known as ladders for voltages and signals. These steps are
given below.
ALWAYS VOLTAGE Checking
This voltage generates before the power on the button is pressed. 3Volt
is given to SIO and EC BIOS.
After Pressing The POWER BUTTON
Once the power button presses SIO to inform PCH and turn buck
converters one after another.
POWER ON VOLTAGES check
The voltage after power should be produced as given below :
3.3 Volt
5 Volt
1.8 Volt
1.5 Volt
1.05 Volt
CPU CORE
0.9 GFX Core
POWER GOOD Signal Check
PCH receives SYS PWR OK signal confirmation signal saying all power is
ok.
RESET Signal Check
PCH generates a PLTRST signal to clear motherboard junk values and
reset the motherboard.
CLOCK SIgnal Check
CLOCK starts generating different frequencies according to the
requirement of chips.
Starts Reading BIOS
In this step, the CPU starts reading BIOS
(https://en.wikipedia.org/wiki/BIOS).
POST Checking By Motherboard
In this step motherboard test all chips and devices in this process which
is also called ‘Power on self test.’
Motherboard power states for understanding
laptop motherboard power on sequence stages
These are the states of the laptop depending on the power consumption
of the motherboard, you already know the two states which are :
1. You turn on the Laptop.
2. The laptop gets turned off by you.
The motherboard states are referred to in character ‘S…’ Where the x is
a number between 0 and 5.
S0 State Of Laptop Motherboard
Working, the system is fully usable, all the components have their
voltage.
S1, S2, S3 State Of Laptop Motherboard
Sleep, The laptop appears to be off, the laptop consumes less power
than in S0 state, the RAM has its voltage, and is kept refreshed.
To wake the laptop from this Sleep state you need only to press a key on
the keyboard or move the mouse.
S4 State Of Laptop Motherboard
Hibernate, the system appears to be off, and the power consumption is
reduced to the lowest level. An image of the RAM is kept on the disc
(https://en.wikipedia.org/wiki/Hard_disk_drive) because RAM loses its
voltages, to wake the laptop you need to press the power button.
S5 State Of Laptop Motherboard
In this step, the laptop motherboard gets shut down.
Types Of Motherboard Voltages For Power On
Sequence Stages
There are four stages in the laptop motherboard
(https://displaymonk.com/ics-in-laptop-motherboard/) which are given
below:
Always Supply Voltage Type (ALWS or AUX or AL)
These voltages are always present even when the laptop is off, on one
condition: the battery should be placed or the charger plugged in.
Thises voltages are:
5 Volt DC (https://en.wikipedia.org/wiki/Direct_current)
3.3 Volt DC
The 5 Volt and 3.3 Volt come from Voltage generator ICs in the
motherboard (https://displaymonk.com/chipsets-and-ic-in-india/).
Suspension Voltage Type (SUS ON)
These voltages are present in suspended or sleep mode (S1, S2, S3):
5 Volt DC
3.3 Volt DC
RAM voltage (For DDR1 – 2.5 Volt, For DDR2 – 1.8 Volt, For DDR3 – 1.5
Volt, For DDR4 – 1.2 Volt)
Note that the 5 Volt and 3.3 Volt are not the same % Volt and 3.3 Volt is
Always voltage, there is another voltage generator that generates those
5 volts and 3.3 Volt.
Power On Voltage Type (RUN) (S0 State)
All the components have now their voltages. There is a supply of 1.05
Volt and 1.8 Volt is also done.
CPU Core Voltage Type
CPU requires core voltage, for example, a high current of approximately
20 Amp to 30 Amp. The newer motherboard graphics chip is also
integrated into the CPU. So the graphics Core voltage is also required.
These voltages are GFX core voltages. These voltages are approximate:
CPU Core = 0.8 Volt to 1.5 Volt / 20 Ampere
(https://en.wikipedia.org/wiki/Ampere) to 30 Ampere.
GFX Core = 0.8 Volt to 1.5 Volt / 10 Ampere to 20 Ampere.
Laptop Motherboard Power Plane
There are two power input sources in a laptop motherboard one is
adapter input and another is battery input.
The adapter input and battery charging section are called VIN ( Voltage
Injection) sections. This section decides which power needs to be sent
inside. This section has another task called battery charging. there are a
number of buck convertors
(https://en.wikipedia.org/wiki/Buck_converter) used according to fulfill
the requirement (https://displaymonk.com/3-must-know-the-basics-oflaptop-chip-level-repair/).
Laptop Mother Powe Plane To Understanding
Laptop Motherboard Power On Sequence
Stages
Voltages
Voltage Type
3.3 Volt
Comes As Always Voltage
5 Volt
This Also Always Voltage
3.3 Volt
Suspended Voltage
5 Volt
This Also Suspended Voltage
1.5 Volt
System Run Voltage
1.8 Volt
This Also System Run Voltage
1.05 Volt
System Run Voltage
0.75 Volt
This is Also a System Run Voltage
GFX Core
Graphics Core Voltage
CPU Core
CPU Core Voltage
Knowing the motherboard model number is important to find the
laptop motherboard power sequence. Especially when we try to find
out the Laptop Motherboard Power Sequences.
It helps to find pictures, schematics, board views
(https://displaymonk.com/boardview-softwares-free-for-windowsoperating-systems/), and known issues. There is always a number
written on the board itself. In some cases, there’s also a sticker that tells
a variant.
Common Laptop Motherboard Manufacturers
For Laptop Motherboard Power On Signals
Below are some of the common laptop motherboard manufacturers
Quanta
Quanta motherboard (https://displaymonk.com/quanta-motherboardidentification-number/) found is HP, Dell, Acer, Toshiba, and a few
Lenovo laptops. The model number on the board is “DA0xxxxMByyy”
(first 0 is optional), “xxxxx” is the actual model, and “yyy” contains the
revision. For example DAY11AMB6E0 for Quanta Y11A rev E.
Compal
Compal motherboard found in HP, Dell, Acer, Toshiba, Lenovo.
Secondly, the model number is “LA-xxxxP” (P is optional), the older, the
lower the number is like LA-4082P from 2007 or LA-E541P.
LCFC
Found in Lenovo, it’s actually Compal. The model number is “NM-xxxx”.
Wistron
Found in Acer, Dell, HP, Lenovo. The model number is an “xxxx-x” (x
being a digit), often associated with a name. For example “Ricjie MB
11241-1”.
Inventec
They make Toshiba, HP, and Some Acer motherboards. Secondly, their
model is number is often “xxyyzz” with “x” being a letter, “y” a digit,
and “z” as the optional letter.
There is also a “6050xxxxxxxx-MB-xx” number that can be easier to spot.
For example “SA10E” and “6050A2052401-MB-A04” for Inventec.
Foxconn
Foxconn motherboards are found in Sony, Some HP laptops. HP has a
weird model number like “CHICAGO_HR_HPCMV_MB_V1” or
“PM_I_HPC_S_MV_MB_V3”.
Sony comes with an “MBX-xxxx” number that’s easy to identify, and
other numbers, like “MBX-202” and “M790”.
Pegatron
Pegatron motherboards are found in a few Acer and Toshiba
motherboards. Acer, in general, has an “xxyyzz” with “x” being a letter,
“y” a digit, and “z” an optional letter. Toshiba has a weird model
number like “PLF/PLR/CSF/CSRUMA”.
Whereas the following manufacturers make their own boards (except
maybe a few models here and there):
Apple
Apple board model number is “820-xxxxx”, like “820-3462”. It’s written
black on a black surface so it’s hard to spot.
Asus
Asus board model number follows the same format as the laptop model
number. Secondly, It can be the same or similar, and sometimes
different.
MSI
MSI model number is “MS-xxyxz”, with x being digits, y a digit or letter,
and z an optional digit for revision. Some boards have two different
model numbers like “MS-16J5” and “MS-1795” (with a 1 appended for
the revision.
Samsung
Samsung model number is the name associated with a “BA41-xxxxxx”
number, like “Bremen-D” and “BA41-01197A”.
Clevo
Clevo manufactures laptops for a lot of “small local” brands. There are
two model numbers on the board, “6-71-W25S0-D02” and “W251ESMBD0”.
HanStar (https://en.wikipedia.org/wiki/HannStar_Display_Corporation)
doesn’t Design motherboards so we did not put them on the list. But
rather HanStar manufactures the PCB. “J MV-4” and “94-V0” do not
board model numbers, they are generic markings about PCB
characteristics.
List Of Laptop Motherboard Power On Signals
The following are laptop motherboard power on signals:
SIGNAL NAME
DESCRIPTION
VCC
3 Volt power to SIO and BIOS
ECRST
RESET to SIO
LID SWITCH
The lid sensor should work
THERMTRIP
The thermal trip should normal
Clock SIO
32.7khz clock from either PCH
EC BIOS
EC BIOS should perfect
RTCRST
RTC RESET and crystal 32khz should to PCH
VCCDSW3_3
Power to PCH
DPWROK
Power OK Indication for the VccDSW3_3 voltage rail
PWRBTN (NBSON)
Power switch 3 – 0 – 3 variation
RSMRST
SIO generates 3 Volt at this pin
PM_PWRBTN (DNBSW
Post power button to PCH 3 Volt variation.
ON)
SLP_4
PCH generates 3 Volts send to SIO giving confirmation to turn on t
SLP_3
he power
SYSON, SUSP, VR ON
All buck converters turn on one by one
Signal Name And Description For Laptop Power
On Signals
When power is connected either from the adapter
(https://displaymonk.com/laptop-adapter-charger-guide/) or battery
(https://displaymonk.com/laptop-battery-charging-circuit-repair/) to
the motherboard it passes from various stages.
Below mention a chart given signal name and their description.
SIGNAL NAM
DESCRIPTION
E
VIN voltage
Check the input voltage to this current sensing resistor
VIN
VIN is 3 Volt and 5 Volt section input voltage to 3 Volt and 5 Volt chip
VREG3
3 Volt linear output from 3 Volt and 5 Volt section which is going to SIO
VCC
SIO gets 3 Volt at its power input pin
ECRST
EC reset signal 3 Volt reset to SIO
THERMTRIP
THERMTRIP thermal signal
LID SW
LID SW is a magnetic lid sensor
BIOS
EC BIOS starts communicating with SIO
NBSWRON /
The power switch when we press 3 Volt goes zero and then again comes
PWRBTN
to 3 Volt. Moreover, you can see their 3 Volt variation.
ECON
SIO generates an ECON signal and turns on always section 3.3 Volt and 5
Volt buck converter output.
3.3 Volt ALW,
3.3 Volt and 5 Volt Buck converter output voltage.
5 Volt ALW
PCH_PWR E
SIO generates this signal and provides power to PCH
N
VCCDSW3.3
PCH power management section gets 3 Volt power
SIGNAL NAM
DESCRIPTION
E
DPWROK
This signal is confirmation to PCH power 3 Volt
RTCRST
RTC reset signal 3 Volt
SUSCLK
32.7KHZ clock frequency to SIO
RSMRST
SIO sends a 3 Volt signal to PCH to reset and resume called RSMRST
DNBWORON
SIO sends post power button signal to PCH 3 Volt to zero and back
PMBTN
SLP_S4 (SUS
3 Volt power plane wake up signal to PCH to reset and resume called RS
B)
MRST
SPL_S3 (SUS
3 Volt power plan wake up signal from PCH to SIO
C)
SYSON,
SIO turn on all buck converter one by one
SUSP,
VR ON
Power On Sequence Diagram For Laptop Power
On Signals
Below are the diagrams for laptop power on signals.
Laptop Power On Signals For General
Motherboards
Below is the power on signals for general Motherboards.
SIGNAL N
DESCRIPTION
AME
CURRENT
Check here 18 Volt. Secondly, if not coming then check 1st or 2nd MOSF
SENSING
ET (https://displaymonk.com/laptop-motherboard-components-list/) or
RESISTOR
battery charging chip (https://displaymonk.com/repair-laptop-battery-c
harging-section/)
VIN
DC Voltage input to always voltage chips at its VIN pin
VREG3
3 Volt linear output from the chip
VCC
3 Volt power to SIO and BIOS
ECRST
3 Volt reset signal to SIO
AC OK
3 Volt signal coming from battery charging chip indicating power comin
g from adapter.
SIO start communicating with BIOS
NBSWRON
The power switch goes zero and comes back to 3 Volt
S5_ENABL
After the power button is pressed SIO generates an S5_ENABLE signal to
E
3 Volt and turns on the 3 and 5 Volt section
VCCDSW3
This 3 Volt power turn on PCH
_3
DPWROK
Power ok to PCH 3 Volt
SUSCLK
32.7KHZ clock frequency coming from PCH to SIO
SIGNAL N
DESCRIPTION
AME
RSMRST
Resume Reset Signal
DNBWRON
Post power button signal generate from SIO to PCH
PM_PWRO
N
SLP_3
Wake up signal generated by PCH send to SIO
SLP_4
SUS ON
Buck converter on signal
SYSON
Laptop Power On Signals For Quanta
Motherboards
Below is the power on signals for Quanta Motherboards.
SIGNAL NAME
DESCRIPTION
3.3 VAL
3 volt linear goes to SIO VCC pin
PWRBTN NBSWON
power button
SLP_S5
when power press SIO sends SLP_S5 signal to enable 3 Volt and 5
Volt supply
5 Volt
5 Volt buck converter output
3.3 Volt
3.3 Volt buck converter output
RSMRST
SIO sends 3 signal PCH
PM_PWRBTN
post power button from SIO to PCH goes low and back high
SUSC, SLP_S4, _S3
wake up signal sent by PCH to SIO to turn on the laptop
SUS ON
This signal release 3 Volt and 5 Volt
5 Volt SUS
SYSON
system on signal turn on the buck converter
1.5 Volt (DDR3)
MAIN ON
main on signal turn on 1.05 Volt and 1.8 Volt
1.05 Volt, 1.8 Volt
1.05 Volt and 1.8 Volt
HWPG
when all power ok then the HWPG signal generates 3 Volt and is gi
ven to SIO
SIGNAL NAME
DESCRIPTION
VR_ON
once SIO receives the HWPG signal is generated a signal to the VR
M section
VCC / GFX CORE
CPU core and GFX core voltage generated and given to CPU
IMVP PWRGD
when CPU core voltage stable VRM chip sends this power good sig
nal
ECPWORKS (SYS PWR
When all powers is ok including CPU SIO generates this 3 Volt sign
OK)
al to PCH
DRAM PWRGD
ram power ok signal
PLTRST
CS READ
PCH read BIOS
Laptop Power On Signals For Quanta 4th
Generation Motherboards
Below is the power on signals for Quanta 4th generation Motherboards.
SIGNAL NAM
DESCRIPTION
E
POWER
power input from the adapter and battery charging section. This voltage
is approximately the adapter input voltage.
3.3 VAL
this is 3 Volt linear output from the Always Voltage Section. This power g
oes to the SIO VCC pin.
PWRBTN (NB
this is the power button. It is normally 3 Volt when we press a power but
SWON)
ton it goes to 0 and comes back to 3.
SLP_S5
this signal is sent by SIO to turn on Always voltage after the power butto
n is pressed.
5 Volt
5 Volt and 3 Volt are always voltage.
3.3 Volt TO P
this voltage to going to CPU to turn on its power. It is called VCC DSW.
CH
RSMRST
This is a 3 Volt resume signal generated by SIO to resume further sequen
ce.
PM_PWRBTN
This is a post power button from SIO to CPU.
SUSN, SLP_S
Wake up the signal from the CPU to turn on different Buck converters.
3
SUS ON
Suspend voltage turn on.
5 Volt SUS
This is the 5 Volt and 3 Volt suspend output.
SIGNAL NAM
DESCRIPTION
E
1.35 Volt (DD
1.35 Volt buck convertor turned on.
R3)
MAINON
Turn on the main power from SIO to the buck converter.
1.05 Volt
1.05 Volt buck converter turn on.
HWPG
All power good signal when all the buck converter is working then HWP
G signal is generated.
VR_ON
CPU core voltage turn ON signal.
VCC_CORE
CPU core voltage.
IMVP_PWRG
CPU core voltage ok.
D
DGPU_PWR_
Graphics core voltage power good. This gives enables the signal to a 1.5
EN
Volt buck converter.
GFXCORE
Graphics core voltage.
DGPU_VC_E
Graphics core voltage power good. This gives Enable signal to a 1.5 Volt
N
buck converter.
1.5 Volt
1.5 Volt buck converter voltage output.
DGPU_PWR
Power ok signal to SIO.
OK
SIGNAL NAM
DESCRIPTION
E
EC_PWROK
All the power plans are ok including the CPU core, SIO generates this sig
nal, even to the CPU.
SYS_PWROK
All system powers are working fine.
PLTRST
Platform reset. CPU generates the platform reset to reset the entire mot
herboard after it receives the system power ok signal.
DRAM RST PI
Reset signal to the RAM.
N NO 30
Laptop Power On Signals For Wistron
Motherboards
Below is the power on signals for Wistron Motherboards.
SIGNAL
DESCRIPTION
NAME
VREG 3 V
3 volt linear output from always section going to SIO power
olt
S5 ENAB
from SIO to always section buck converter enable pin
LE
VCCDSW
this is the power to PCH 3 Volt
RTC CLK
RTC section generates 32.7khz clock frequency after RTCRST signal
RSMRST
resume and reset 3 Volt signal generated by SIO to PCH
PM_PW
post power button signal generate by SIO 3 Volt variation going to PCH
RBTN
SLP_S4
SLP_S4 signal is wake up signal sent by PCH to SIO.
SLP_S3
SLP_S3 signal is wake up signal sent by PCH to SIO.
1.8 Volt
1.8 Volt buck convertor turn on.
RUNPW
after generating 1.8 Volt this buck converter generates power good
RK
1.05 Volt
RUNPWROK power good signal goes to 1.05 Volt buck converter.
VTTPWR
when 1.05 Volt out then it generates power good and it goes enable to 0.
GD
85 VTT enable.
SIGNAL
DESCRIPTION
NAME
0.85 Volt
0.85 Volt buck converter turns on.
IMVP_VR
CPU core enables signal.
_ON
VCORE
CPU core voltage output.
SYS_PW
IMVP PWRGD signal generates after CPU core voltage stable and this sig
ROK
nal goes to PCH. This signal sends all power ok called SYS_PWROK
DRAMP
RAM power ok.
WRGD
CPUPW
CPU power ok.
RGD
PLTRST
platform reset generated by PCH and reset entire motherboard.
Laptop Power On Signals For WISTRON 5th
Generation Motherboards
Below is the power on signals for Wistron 5th generation Motherboards.
SIGNAL NAME
DESCRIPTION
ACIN
adapter voltage input
VREG 3 Volt
3 Volt linear output from always 3 Volt and chip
S5_EN
SIO sends this signal to enable 3 Volt and 5 Volt section
3 Volt and 5 Volt ALW
buck converter output
RSMRST
SIO sends resume signal to CPU
ON OFF SWITCH
power button
PM PWRBTN
post power button from SIO to CPU
SLP_S3
CPU generates this signal to turn on all buck converters.
1.35 Volt
DDR3 supply turns on.
1.05 Volt / 1.5 Volt
1.05 Volt and 1.5 Volt buck converter turns on.
RUNPWROK
power good signal
H_VCCST_PWRGD
all power good signal
CPU CORE
CPU CORE voltage
IMVP_PWRGD
CPU power good signal output from VRM section
DRAMRST
reset signal to DDR
BIOS
CPU reads BIOS
For making a career in laptop chip level repai
(https://displaymonk.com/laptop-chip-level-repair-career-guide/)r you
must have knowledge about basic Chip Level components
(https://displaymonk.com/laptop-motherboard-components-list/) too.
There is also a guide for desktop motherboard power sequence
(https://displaymonk.com/the-power-sequence-in-desktopmotherboard/) which is similar but much smaller compared to laptop
motherboards.
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