PSU 12V only in ATX Bauform für Fujitsu Mainboards

Main Features

• Active PFC Circuit
• Full Range Input
• Eup Lot 6 -2010
• FCC Part 15 Subpart J, Class ‘B’ 115 Vac operation.
• CISPR 22 Class ‘B’ 230 Vac operation.
  

 

Output Rating

Output	Nominal	Regulation	Ripple/Noise	Min	Max	Surge
1	+12V1	±5%	120mV	0,05A total	15,0 A	18,0 A(20S)
2	+12V2	±5%	120mV	0,05A total	15,0 A	18,0 A(20S)
3	+11Vaux	10,20V-11,80V	240mV	0 A	1 A

Conventional topology (Multioutput PSU)
After dissipate the 220 voltage coming from the electricity network into 12V, the traditional multi rail power supply unit and its topology splits up the needed DC / DC converters in an extra circuit and apport ions the 12 V into 5 V and 3.3. V. These smaller voltages are then conducted to the mainboard and apart from the 3.3 voltage also to the Hard Disk Drive and the ODD, which are again connected to the mainboard themselves.
 

By dividing the voltage already in the PSU this system leads to:   
 

 
 
12 V only topology
A 12V only system requires a special mainboard design plus an appropriate power supply which is available from FSP Technology Inc..
 
Overview 12V only mainboards by Fujitsu:
D3062-A:   μATX, Intel Q67
D3061-A:   μATX, Intel Q65
D3162-A:   μATX, Intel Q77
D3161-A:   μATX, Intel Q75
D2991-A:   μATX, Intel B61
D3171-A:   μATX, Intel B75

Appropriate 12V only PSU:   
FSP Technology Inc. model name:  FSP250-30PFJ  
 
The PSU is generating only 12V. DC/DC converter will produce 5V & 3.3V for the system, where they are needed (e.g. drives & PCI slots). Traditionally 3.3V are produced in PSU with magnetic components, which have higher losses, than DC/DC converters on motherboards with our novel approach.       
 

 

This integrated system provides a number of clear benefits, which are presented below.
 
Elimination of cross load problems In contrary to standard multi rail power supplies the 12V only power supply does have only one voltage that needs to be kept under control. Known issues with cross loads from multi rail PSU’s do no longer exist.   
 
The crossload problems, load distribution between 12V, 5V & 3.3V , of multioutput PSU are traditionally quite complex problems for system designers. It is obvious from picture 1, that only one converter is available, which is been controlled by one PWM signal. However 3 output voltages are generated. Now there are potential load cases possible, where high load can appear at 3.3V while 5V & 12V is barely loaded. This leads to critical conditions, for the system  operation, especially when dynamic load  changes happen. New INTEL Q67, B65 systems do have excellent idle power consumption; however the dynamic load and step load range will further increase compared to previous systems.
 
The novel 12V only approach simplifies the life for system designers dramatically. Crossload conditions need not to be considered any more, as the PSU in producing only 12V. All other voltages are been produced  by separate regulators on the systemboard. As the PSU needs  only to regulate one output voltage, the dynamic performance will be better than on multi output PSU, which brings another benefit to the system designer.

Cost considerations
Costs for the PSU will drop, as 5V and 3.3V generating circuits will be removed. For the mainboard it might increase only just  a little bit. Overall the costs will drop as soon volume for the PSU will increase. For cost comparison it is always important to compare the efficiency level of the PSU and the used regulators on the motherboard.
 
Homogenous system design possible
With this combination of mainboard and PSU a new homogenous system design is possible not affecting all other components. The power and data cable assembly to the storage drives (ODD/HDD) can be combined in order to improve the clean appearance and the airflow th rough the system. Cables will only be fitted into the system, where the installed drives do need them. Many unused cables are therefore not anymore present.
 
Less noise level
The PSU FSP250-30PFJ by FSP Technology Inc.  is featured with Fujitsu’s innovative system management technology. Thereby the onb oard system management controller of the Fujitsu mainboards controls and supervises besides the CPU and system fan the PSU fan as well. Sys tem designer have an overall possibility to adjust the fan speed, thermal conditions and noise level of their system.
 
The 12 V Only System is not an industry standard yet but a proprietary solution, which is currently implemented by all Tier 1 Systembuilders like e.g. Dell, HP, Fujitsu