What is ATX and how come nothing is made by any manufacturer yet?
Full English name: AT eXternal
It is a PC motherboard architecture specification announced by Intel in 1995.
ATX is a new personal computer motherboard specification. It was proposed and developed by Intel and echoed by other manufacturers. The motherboards we currently use are a specification known as Baby AT. The ATX layout is the equivalent of turning a Baby AT motherboard 90 degrees, changing a straight Baby AT motherboard into a horizontal one, which is the biggest specification change for motherboards. This allows motherboard and computer manufacturers to continue to utilize their current production facilities, facilitating the design and production of motherboards at a lower cost.
ATX power supply technology in detail
(ZT)
At present, ATX power supplies are widely used in computers, and compared to AT power supplies, they are more in line with the energy-saving standards of "green computers"
At present, it corresponds to motherboards that are ATX motherboards.
1. Characteristics of the ATX power supply
Compared with the AT power supply, the ATX power supply increased "+3.3V, +5VSB, PS-ON" three outputs.
3.3V" output is mainly for CPU, while "+5VSB" and "PS-ON" outputs reflect the characteristics of ATX power supplies. The ATX power supplies are characterized by
The main feature of the ATX power supply is that it does not use the traditional mains switch to control whether the power supply works or not, but
uses the combination of "+5VSB, PS-ON" to realize the power on and off, as long as the control of the As long as you control the change of "PS-ON" signal level, you can control the power on and off. The power supply is turned on when the "PS-ON" is less than 1V and turned off when it is greater than 4.5V
.
2. ATX power supply core circuit
ATX power supply main converter circuit and AT power supply is the same, is also the use of "double half-bridge it excitation" circuit, PWM (Pulse Width Modulation) controller is also the use of the TL494 control chip, but canceled the utility switch.
Because the utility switch is canceled, so as long as the power line is connected to the conversion circuit will have +300V DC
voltage, while the auxiliary power supply to the TL494 also provides the operating voltage for the start of the power supply to prepare.
ATX power supply is characterized by the use of TL494 chip pin 4 of the "dead drive control" function, when the pin voltage is +5V
, TL494 pin 9, 11, no output pulses, so that the two switching tubes are cut off, the power supply is in a standby state, no power
voltage output. When pin 4 is 0V, the TL494 will have trigger pulses to the switching tubes, and the power supply will enter into normal operation
state. One output of the auxiliary power supply is sent to the TL494, and the other output is obtained by the voltage divider circuit to get "＋5VSB" and "PS-
ON" two signal voltages, which are all +5V. "The +5VSB output is connected to the ATX motherboard's "power supply monitor
control component" as its operating voltage, and the +5VSB output is required to provide a 10mA operating current. The "+5VSB" output is required to provide 10mA of operating current. The output of the "Power Supply Monitor
Control Unit" is connected to "PS-ON", and when its trigger switch (non-lock switch) is not pressed, the "PS-ON" output is connected to "PS-ON", and the "PS-ON" output is connected to "PS-ON". -
ON" is +5V, it is connected to the positive phase input of the voltage comparator U1, and the voltage of the negative phase input of U1 is 4.5V
right, so the input of the voltage comparator U1 is +5V, and it is sent to the TL494's "dead drive control pin". "
The ATX power supply is in standby mode. When the motherboard's power monitoring trigger button switch (mounted on the panel of the main chassis) is pressed, "PS-ON" becomes
Low, then the output of the voltage comparator U1 is 0V, so that the ATX mainframe power supply is turned on. Pressing the trigger switch on the panel again will turn PS-ON to +5V and turn off the power. At the same time, you can also use the program to control the output of the "Power Supply Monitoring
Control Component", so that "PS-ON" will be changed to +5V, and the power will be turned off automatically. For example, in WIN9X platform, the ATX power supply will be shut down automatically when the shutdown command is issued.
The ATX power supply will be automatically shut down when the shutdown command is issued.
3. Failure analysis of the motherboard can not power
Because the ATX power supply is subject to the motherboard's power monitoring components, so when the ATX host can not be charged
The failure can not be immediately determine the fault is the power supply itself or the motherboard's "power monitoring components", to the repair of the
When the power supply fails, the motherboard will not be able to immediately determine whether the failure is due to the power supply itself or the motherboard's "power monitoring component," making maintenance difficult.
Based on the above analysis, we can connect a resistor of about 100 OHM between the PS-ON output and ground to make
"PS-ON" become low.
Data Ready is a video ready to go. At the same time, it also suggests me
that if the ATX motherboard's "power monitoring component" fails, because it is difficult to repair, we can
skip the "power monitoring component", and control the "PS-ON" directly. We can skip the "power monitoring component" and directly control the voltage of "PS-ON" to turn on or off the host computer. Of course, the auto shutdown function of the mainframe is not available at this time.