Switching Power Supply: PC Power Analysis

Some people compare the CPU to the "heart" of the computer. In fact, if we really compare it visually, the CPU is more like a brain to the computer, and the heart that really powers the computer should be to provide sufficient power to the computer. power supply. So let's take a look at this corner that we overlooked.

PC power has experienced nearly 20 years of development since it was produced. During this period, there have been many changes in the shape of the power supply as well as output voltage, power, and electrical performance, and many different specifications and standards have appeared. To date, there are still many types of power supplies coexisting on the market. Different types of power supplies are designed for different types of mainframes. Therefore, it is necessary to correctly distinguish the type of power supply.

IBM PC/XT/AT is the earliest industrial standard for PC power supplies. The popularity of the concept of compatible computers enables a relatively uniform design of PC power supplies and establishes a power bus with four output voltages of +5V, +12V, -5V, and -12V. Architecture. Among them, +5V is responsible for the power supply of almost all logic chips to meet the requirements of the +5V TTL logic level that has become the industry standard, and +12V is mainly used for the power supply of hard disks and optical drive motors in the machine. The connection between the AT power supply and the motherboard is two single-row 6-wire cables, which are P8 and P9 respectively. The most obvious sign of the appearance of the AT power supply is its AC input switching line. Due to the safety requirements of the AC input line, this cable has a thick insulating sheath and is very easy to identify.

The appearance of ATX power is a major change in PC power. A +3.3V main output is added to the ATX power supply, adding +5VSB standby output and PS_ON# signals. +3.3V is designed for parts with lower power consumption and lower logic voltage. The increase of +5VSB and PS_ON# is to meet the needs of new power management solutions such as PC's remote power-on/off switch and keypad switch. The output cable connecting the power supply to the motherboard also extends from the original 12-core to 20-pin, and uses a double-row 20-pin plug. The design specifications for PC power supply have also been gradually established and improved. Typical is the INTEL "ATX POWER Supply Design Guide" and "SFX POWER Supply Design Guide" accepted by the industry. These two standards are still the most important reference in the design of PC power supplies.

The P4 power supply is a type of power supply that is currently attracting attention. Its official name is the ATX12V power supply. When INTEL introduced its next-generation Pentium 4 CPU, it also proposed a power standard that was adapted to system changes, namely the "ATX/ATX12V POWER Supply Design Guide." "ATX12V" is used as the "advanced series" in the ATX series power supply. Compared to ATX, the ATX12V power supply has the following two obvious changes:

1. Increase the +12V output capability. The CPU, Chipset, etc. on the mainboard have their own specific operating voltage and need to rely on VRM or local DC/DC to supply. With the rise of IC power, using +12V to power these parts is better than using +5V or +3.3V. Easy to transmit more power and have higher transmission efficiency.

2. Added +12V output line and connectors. In order to make a good transmission of the +12V current, a 4-pin +12V plug is added. This plug also becomes the appearance characteristic of the ATX12V power supply.

In addition, another change in the ATX/ATX12V series power supplies is the increase in +5VSB output current due to the need to adapt power management solutions such as "Instantly Available PC" and "Suspend-to-RAM."

One of the most common types on the market is the standard AT/ATX form factor ATX and ATX12V power supplies. The power supply power is mostly between 200W and 300W. We can choose according to the needs of different hosts.