CPU single-phase power supply circuit detailed and check maintenance process

This article has three parts: CPU Main power supply circuit composition, CPU single-phase power supply circuit Working principle (take HIP6021 power IC as an example), the CPU single-phase power supply Circuit maintenance flow detailed explanation. Thank the Shenzhen Red Police computer maintenance Training School to provide technical information to support this article.

General composition of power supply circuit

CPU main power supply is an important condition of CPU work, mostly by power supply IC, field effect tube, inductance coil, capacitance and so on, sometimes will add voltage regulator diode, transistor composed of CPU main circuit.

Computer motherboard motherboard power, Power IC (also known as PWM control) began to work, the issue of pulse signal, so that two FET rotating conduction, when the load at both ends of the voltage vcore (such as the CPU required voltage) to reduce, through the MOSFET field effect Tube switch function, The external power supply charges the L2 inductance and achieves the desired rated voltage.

When the load at both ends of the voltage rise, through the MOSFET field effect tube switch role, external power supply disconnect, inductance L2 released just filled in the energy, then the L2 inductance will become a power supply continue to the load. With the consumption of energy stored on the L2 inductor, the voltage at both ends of the load is gradually lowered, and the external power supply is recharged by switching the MOSFET field effect tube. In the process of continuously charging and discharging, the line becomes a kind of stable voltage, so that the voltage on both ends of the load will never be increased or lowered. The power supply diagram is as follows:

Note: This circuit for Pentiumⅲ before the motherboard often used, the general output CPU core power supply 2.0V, external nuclear power supply 2.5V, the core power 1.5V, Memory 3.3V (also has North Bridge, South Bridge in this way power supply).

Circuit Working principle

CPU Single-Phase power supply circuit Working principle: atx5v after Lin add to Q1 D pole, 12V capacitor filter directly add to HIP3021 VCC, at this time HIP3021 began to work, Through the internal oscillation circuit, the rectangular wave signal is produced by Ugate and Lgate respectively to control the G-pole of Q1 and Q2. When the Q1 received the control signal, and to the inductance Lout1 charge, when the Lout1 charge to reach the rated voltage of 2V (different grades of the CPU is not the same) when the Q1 cut-off, Q2 conduction, The inductance Lout1 discharge output is supplied to the CPU core voltage.

When the LOUT1 inductance discharge is lower than 2V, the Q2 cutoff, the Q1 conduction passes to the inductance again to charge; through Q1 and Q2 rotate the conduction control Lout1 output a constant voltage to supply the CPU. When we plug in the CPU, VID0-VID4 recognized the CPU internal level settings, through the HIP6021 internal A/D-mode conversion, and then through the comparator to control the Q1 and Q2 of the duty ratio, so as to adjust the output to fit the normal CPU voltage.

Powergood is the power signal, when the CPU power is normal, this signal emits the CPU to start work.

FB for feedback signal, feedback circuit monitor output voltage and current exceed rated value, IC through feedback circuit feedback back to adjust the internal control circuit, control Q1 and Q2 duty ratio, always keep output constant voltage and current supply CPU.

Maintenance process

The first manifestation of the failure is that the CPU core voltage (VCore) is not normal. And there are two things:

The first is: CPU core voltage High or Low:

Voltage bias High Check whether the Q1 breakdown or check feedback circuit.

Low voltage check Q2 breakdown or capacitance leakage and short-circuit.

The second type is: no power

First measure Q1 D 5V is normal: if it is not normal to repair the ATX 5V to Q1 D-pole between the circuit (usually rarely bad) if normal to continue the second repair steps:

Check Q1 G-Pole control waveform: If the normal need to replace Q1 and Q2, if not normal to continue the third repair steps:

Check the power supply IC 12V power supply: If not normal on the replacement of 12V power supply insurance resistors or check atx12v to the line between the IC, if normal to continue the fourth repair steps:

Check the VID0-VID4 circuit, if not normal, you need to replace the 5V pull off or related to the monitoring chip, I/O, buffer. If normal, proceed to the fifth maintenance step:

Check the IC around the circuit: if normal to replace the Power IC, if not normal to replace the Ocset-related capacitors.

Experience: General core 1.5V and external nuclear 2.5V abnormal mostly for the output of this voltage field effect tube or regulator tube damage.