ncp5381a ON Semiconductor, ncp5381a Datasheet - Page 27

• Manufacturer Part Number: ncp5381a
• Description: 2/3/4 Phase Buck Controller For Vr10 And Vr11 Pentium Iv Processor Applications
• Manufacturer: ON Semiconductor

controller optimized to meet the Intel VR11 Specifications.
The demo board for the NCP5381A is available by request.
It is configured as a four phase solution with decoupling
designed to provide a 1.0 mW load line under a 100 A step
load. A schematic is available upon request from ON
Semiconductor.
Startup Procedure
an Intel dynamic load tool (VTT Tool) available through a
third party supplier, Cascade Systems. The web page is
http://www.cascadesystems.net/.
the test tool from a separate ATX power supply. The test
tool should be set to a valid VID code of 0.5 V or above
in−order for the controller to start. Consult the VTT help
manual for more detailed instructions.
Startup Sequence
The NCP5381A is a high performance multiphase
The demo board comes with a Socket 775 and requires
Start by installing the test tool software. It’s best to power
10. Using the VTT tool software, select a VID code
12. Set the VID DIP switches. All the VID switches
13. Set the VR_ENABLE DIP switch down or
14. Set the VR10 DIP switch up or open.
15. Set the VID_SEL switch up or open.
11. Connect the second ATX supply to the demo
1. Make sure the VTT software is installed.
2. Powerup the PC or Laptop do not start the VTT
3. Insert the VTT Test Tool adapter into the socket
4. Inset the socket saver pin field into the bottom of
5. Carefully line up the tool with the socket in the
6. Connect the scope probe, or DMM to the voltage
7. Connect the first ATX supply to the VTT tool.
8. Powerup the first ATX supply to the VTT tool.
9. Start the VTT tool software in VR11 mode with
software.
and lock it down.
the VTT test tool.
board and press tool into the board.
sense lines on the test tool. When using a scope
probe it is best to isolate the scope from the AC
ground. Make the ground connection on the scope
probe as short as possible.
the current limit set to 150 A.
that is 0.5 V or above.
board.
should be up or open.
closed.
APPLICATION INFORMATION
http://onsemi.com
27
Step Load Testing
Select the dynamic loading option in the VTT test tool
software. Set the desired step load size, frequency, duty,
and slew rate. See Figures 10 and 11.
The VTT tool is used to generate the high di/dt step load.
16. Start the second ATX supply by turning it on and
17. Set the VR_ENABLE DIP switch up to start the
18. Check that the output voltage is about 19 mV
setting the PSON DIP switch low. The green VID
lights should light up to match the VTT tool VID
setting.
NCP5381A.
below the VID setting.
Figure 10. Typical Step Load Response
Figure 11. Typical Load Release Event