ATX power principle :

1.PRINCIPLES pulse source
1.1. Concept:
-Circuit pulse source (also known as source switches on / off switching) is the inverter shall convert the DC power into AC power.

1.2. The diagram inverter:
There are basically two types of inverter: serial and parallel.
1.2.1.Diagram inverter serial

Pros: Simple, easy to calculate design, easy assembly.

Cons: Allows very low tolerance components. Not isolated mass primary and secondary user should cause shock, danger to sensitive components. Therefore, this type of source is very rarely used.

One of the electronic devices are more civil in Vietnam using serial power inverter is Samsung TVs CW3312, Deawoo 1418.

1.2.2.Parallel inverter diagram:

Pros: Easy to change the output voltage, allowing a tolerance of large components. Mass isolated primary and secondary good, safe to use and download.

Cons: Circuit complex, difficult to repair

Due to the good isolation ability of parallel inverter circuit used in all the computer power supply, between AT and ATX. This series will focus on analyzing parallel circuit inverter ATX power.

2.COMPUTER RESOURCES (ATX)
2.1. Functions:
Civil transform AC (in Vietnam is 220V/50Hz, Japan is 110V/60Hz ...) into the DC voltage supply for the PC.
The DC power levels include:
+5 V, +12 V, +3.3 V,-5V,-12V, +5 V STB (standby before, wait), +4.5-5V PS-ON (Power Switch On - switch to open / power), +5 V PG (power good - the good, the synchronization signal for all circuits in the PC boot).

2.3. Functional blocks:
(1) Protection of the source and load when lightning, voltage surge.
Filter, remove or reduce industrial noise pulses through AC power goes to the ATX power circuit, if such interference can not be eliminated ignition source circuit, the load, reducing the work load stability.
(2) Break open the excitation, in order to create an electric current is not continuous on the main transformer to take advantage of the phenomenon of electromagnetic induction induced voltage on the secondary.
(3) The load capacity of the, create secondary output voltage, and the isolation between the two blocks primary / secondary to eliminate mass (voltage) of the primary load and user protection.
(4) As a small power inverter circuit, you can use vibration or blocking
(5) The load capacity of the previous level, in order to create the previous voltage level consists of two levels: 5V, 12-16V supply range, PS-ON, STB and amplified stimulated.
(6) Bending, filter, voltage regulator launched the DC voltage standby.
(7) As an RC oscillator circuit to generate square pulses of fixed frequency (older sources 13KHz frequency, the source of life that is 19KHz). This pulse is sent to the power control open / close. Pulses from the oscillator pulse width (tx) change in the output voltage, if the voltage is higher than the design, the pulse width decreased. Conversely, if the output voltage is lower than the design, the pulse width increases. So IC implementation oscillations called PWM (Pulse Wide Modulation pulse width control)
(8) Magnification increased pulse amplitude control. The input of the circuit is the square pulse from the oscillator circuit.
(9) As the load of stimulus oscillation amplifier circuit for the purpose of coupling excitation to the main power, and no loss of isolation between the primary and secondary.
(10) Includes adapter circuit, filter, voltage regulator. Input AC voltage is removed from the main power transformer, the output is stable voltage dc taken to jack ATX.
(11) the feedback circuit voltage stability or down range when the output voltage is too large, oscillation breaks when there is a short circuit load to protect the source and load protection (prevent further damage)
(12) Amplifier circuit algorithm will work after the machine is turned on, the voltage generated PG time appeared PG will be later than the primary voltage of about 0.2-0.5 seconds, to wait for the output voltage has stable. PG included in the main and stimulate all the main circuit starts operating at any one time (synchronous time base)