Is there a maximum in-rush energy limit for devices hot-plugged into PCI expansion
cards? The 1394-1995 spec states:
"The inrush energy shall not exceed 18 mJ in 3 ms."
but I don't see any inrush spec. in the PCI spec.
We've seen some devices that exceed the 500 mA tolerance on the PCI 12 V rail
when hot-plugged into a PCI 1394 adapter card. This in itself doesn't seem to be
a problem, but we have seen one PC system that gets reset when a 1394 hard drive
is hot-plugged and the inrush current peaks around 4.5A (with a 600 us duration).
It looks like the 12 V rail drops and causes the POWER GOOD signal to get deasserted.
There is a 750 mA slow fuse on the PCI card 12 V trace.
Is the Power Supply Rail Tolerance of 500 mA for the 12 V rail a "Maximum" current?
All insight and comments are greatly appreciated.
Regards,
Joe Fockler
Texas Instruments
1394 Host Controller Group
12500 TI Blvd., MS 8731
Dallas, TX 75243
(214) 480-6064 phone
(972) 761-6954 fax
email: jfockler@ti.com
Visit our Bus Solutions website:
http://www.ti.com/sc/1394
http://www.ti.com/sc/pci