HP 8000 HP Enterprise/Mid-Market Desktop PC Power Supply Architecture - Page 10

(DDR2) to +1.5V (DDR3). This trend will continue as legacy standards, such as PCI, are replaced by newer standards, such as PCI Express. The most common voltage requirements on the PCA that consume a majority of system power are ≤ +1.5V. Any available voltage +3.3V or greater can be used generate these lower voltages. The new HP power supply architecture utilizes +12V to generate lower voltages. While +5V and +3.3V will be needed for a long time to come, they are no longer used as a high-powered source that justified their place in the ATX power supply interface standard. Notebooks, already single voltage systems, regulate +5V and +3.3V on the motherboard. Other server and blade products have also removed +5V and +3.3V from the power supply output. PCs are trailing in this transition, but the USDT and All-in-One form factors with external power supplies have already moved in this direction. Removing +5V and +3.3V from the new HP power supply architecture improves the overall efficiency of the power supply, thus allowing HP to deliver more innovative solutions to our customers. +5V Standby vs. +3.3V Standby The traditional standby voltage from the power supply is +5VSB. However, +5VSB does not directly provide power for any function on the motherboard in the S5 off system state, except for possibly a few microamps. The +5VSB provided by the power supply is only used to generate +3.3VSB and other lower voltages with very low efficiency. This is another technology change that has occurred since the introduction of the ATX standard. The continued use of +5VSB in the power supply to generate +3.3VSB on the motherboard is very inefficient and is an obstacle to meeting the required low power off-state requirements defined by the EuP Directive. The primary off and sleep-state voltage of +3.3VSB can be generated from any higher voltage, including +12VSB. The primary use for +5VSB is for USB and PS2 S3 sleep-state wake events, also with very light loading. Most, if not all loads, are typically switched to the main +5V and +3.3V power sources, which support higher load currents, leaving +5VSB unused and unnecessary when the power supply is on. If all loading on +5VSB can be transferred to other sources, the +5VSB output of the power supply can turned off, thus increasing overall power efficiency. The new HP power architecture changes the standby voltage to voltage above +5V and allows the motherboard to generate the standby voltages it needs. This is similar to the single-output external power supplies that produce a single voltage that is always on and the motherboard regulates down to what it needs. The innovative solution creates more opportunities to increase power efficiency and overall power consumption in the sleep and off states to meet the regulatory requirements. 10