CPU motherboard power supply common sense science (dry goods)

Recently, I chatted with readers on the WeChat platform and found that some friends’ common sense about CPU power supply is not very clear. Today I will come to popularize the knowledge about CPU power supply! It doesn’t matter if you can’t understand it for the first time, you can collect it slowly! You can also forward it to friends in need, after all, technology is greater because of sharing.


1. Identify the component of the CPU power supply circuit

There are 5 components of CPU power supply circuit mainly

PWM chip MOSFET inductor capacitor


1: PWM chip (pulse width adjustment chip) CPU power supply circuit commander


Adp3228intelcpu Power Supply 4 Phase P35/P45 motherboard commonly used

EPU = ADP3228 ASUS grinding mark is changed to EPUX58


ISL6336AINTELCPU Power Supply 6 Phase MSI/GIGAC P45/X58 high -end motherboard

ISL6334INTELCPU Power Supply 4 Phase MSI/Gigabyte P45 motherboard commonly used

STL6740LAMD CPU Power Supply 4 Phase MSI/ASUS AM3/AM2+New Main Board

ISL6324AMDCPU power supply 4 phase MSI/ASUS/Gigabyte AM2+motherboard commonly used


PWM chip recognition CPU core voltage, stipulate the number of power supply, adjust the voltage and current, and direct MOS work ISL6336/6334 and ST L6740L to support the power supply phase transformation (APS)

2 Driver-IC drive MOSFET work

PWM chip drives MOSFET through driving chips


Drive chip model is specified by PWM chip

Some PWM chip internal integration driving driving chips

3MOSFET high -power crystal tube (switch tube/field effect tube)

MOSFET is actually a switch.

The attempt current passes, and the current is not allowed to pass when it is closed.

The commonly used MOSFET is single, and the form of packaging is available

D type and Power type. 1 Phase power supply circuit is at least available

2, 1 input/1 output (1 out 1 out),


There are 3 (1 in 2 out), 4 (2 in 2).


4 inductor delay voltage/current rises/decreases

The characteristic of the inductance is that when the current is over, the output voltage slowly increases. For example, input 12V, the output is slowly rising from 0V to 12V.

CPU power supply is to use the characteristics of inductance to reduce 12V to 1.xxv

5 Capacitor: filtering and battery

Fujitsu solid capacitance


Japanese chemical solid capacitance

The current output current is charged with a capacitor, and the current of the capacitor is filtered to filter out some AC ingredients. The current curve is smoother.

The capacitance can be charged/discharged, like a large battery, storage power. Charging the capacitor with an inductive current. When the CPU load increases instantly, the capacitance can instantly provide large current (the response time of MOSFET and inductance is slow).


The capacitance of the power supply circuit is electrolytic capacitance. In the past, the liquid aluminum electrolytic capacitance (the electrolyte of conductive electrical electrical is liquid). When the capacitance worked for a long time in high temperature, the electrolyte will expand the heat and burst.

The commonly used solid aluminum electrolytic capacitance (conductive is a solid polymer polymer). The thermal expansion coefficient is small and will not burst.

Second, the working principle of single -phase power supply circuit

The logic frame diagram of the power supply circuit composed of 5 components


The CPU power supply circuit is the voltage required by the transformer (such as 1.2V) that the transformer required for the CPU core (such as 1.2V)

On the left up, K1 is closed and K2 is disconnected. 12V current flows through the inductance through K1. The inductance resistance makes the output voltage rise slowly from 0V, and the current has gradually increased. At the same time, the electrical energy flowing through the inductance part of the inductance can be transformed into a magnetic energy and stored in the inductive magnet. The output voltage reaches the CPU voltage (such as 1.2V) K1 disconnect and K2 is closed.

In the upper right, K2 and inductance and capacitors constitute a circuit. The magnetic energy stored in the inductance is converted to the power of the electric energy to charge the capacitor. The voltage is slowly reduced from 1.2V, the magnetic energy of the inductance is released, and the voltage drops to 0V. The inductance is completed and the power is completed, and then the K1 is closed again. K1 and K2 repeatedly closed/disconnected, and the 12V current continuously becomes 1.2V for CPU.


Note: K1 and K2 are MOSFET-switch tube (mentioned earlier)

Power supply circuit principle diagram


PWM issues a signal that allows the MOSFET switch to have a certain time width, so this signal is a pulse signal with a certain width. The width (length of time) of the pulse determines the voltage of the inductance output.

PWM is the pulse width modulation. The output voltage through the pulse width.

The signal issued by PWM is weak, and the MOSFET switch is driven by driving the chip to enhance the signal.

The role of MOSFET is only the switch, allowing or prohibiting 12V (1.2V) current through.

The increased voltage of the inductance is the foundation of antihypertensive. When the energy storage of the inductance makes the K1 disconnect, the 1.2V current continues to power through K2. Through K1 is 12V, also known as high -voltage MOS (also called MOS), and the K2 is 1.2V, also known as low -pressure MOS (also called MOS).


The filter effect of capacitance


The output is not a stable 1.2V DC is the pulse of 0V-1.2V-0V.

After the capacitor storage and filtering, the pulsating amplitude reduces the 1.2V DC close to the constant stability.

Principle of PWM chip

CPU VID: Each CPU has a voltage recognition needle,


5-8. The encoding of the VID needle feet defines the voltage of the CPU.

PWM read the code of VID needle foot, know this CPU


Then press VID to determine the pulse width (duty ratio) of the output

Make the switch time and timing of MOSFET.

Monitor the voltage and current of the inductor output, adjust at any time.

Overvoltage protection prevents excessive voltage.

The number of power supply is determined by PWM. At present, the highest is ISL6336, 6 phase power supply.


The number of PWM phase design is generally available, and the PWM of the 6-phase can be selected with 2-6 phase.

The new PWM supports the number of power supply -power supply according to the CPU load, also called APS


Third, the principle of multi -phase power supply work

4 phase power supply icon

Why supply more power

● CPU development: low voltage, large current, single -phase power supply element cannot be met.


● Reduce the ripple of the output current

● Reduce MOSFET and inductance heat


4 The component used in phase power supply circuit is

Pwm of 4 or 6 phase

4 -way PWM output

4 driver chips (integrated in PWM, MOS)

4 groups of MOSEFT (1 in 1, 1 out/1, 2 out/2 in -2 out)

4 inductors (with parallel inductors)

4 Phase power supply output

The picture above shows the 4 -phase power output wave type brown, blue, powder, and green representatives of the four -phase power output wave type 1, 2, 3, and 4 of the oscilloscope indicating that this phase is working. At rest, no voltage output 4 phases are not working at the same time, but in turns in a certain order. The purpose is to reduce the ripple voltage and MOSFET heat.


1 phase/2 phase/4 phase output current comparison

Comparison of stability of the output current: 4 phase is better than 1 phase/2 phase

Capacitors are like storage pools/per phase power supply is like irrigation pump

4 Phase power supply is compared to 4 water pumps, and irrigated water storage pools in turns


Fourth, non -standard multi -phase power supply secrets revealed

Another multi -phase: SPDT switch, 4 turn 8 phase

SPDT is an electronic single -knife double -throw switch connects the PWM 1 phase output to a input terminal of the SPDT, and the corresponding two outputs connect 2 driver chips to drive 2 MOS. In this way, the 4 -phase PWM chip becomes 8 phases through the 4 SPDT chip.

From the four -way SPDT switch ADG333A function frame chart, you can see that the D1/D2/D3/D4 is input. The two-way switch controls signal, so that the D1-D4 can be converted to the S1A-S4A or S1B-S4B output. See the 4 -phase input from the function frame diagram of AS3336G, and output 8 phases. The 8 -way output here uses 4 to 1 group, which is exchanged in turn.


This is the voltage waveform diagram of the 8 -phase output of the 4 phase 8 phase through the SPDT4 to the 8 -phase 8 phase. From the figure, you can see the 8 phase divided into two groups. These two groups also work in turns.

Photo/Battle your sister (CHH)

Edit: Tom

Author: ArticleManager