Suppressing power bus bouncing in a hot-swappable system

Details Suppressing power bus bouncing in a hot-swappable system Suppressing power bus bouncing in a hot-swappable system

2000-12-12

2002-09-10

Luebke, Renee (Department: 2833)

Electrical connectors

With circuit conductors and safety grounding provision

Direct grounding of coupling part member passing into aperture

Reexamination Certificate

active

06447309

ABSTRACT:

BACKGROUND
Contact bounce is a common occurrence during the activation or deactivation of electrical contacts. These electrical contacts may include: push-button switches; toggle switches; electromechanical relays; or power connection devices.
FIG. 1A
shows a graph of a typical contact bounce in an electrical circuit. The graph represents a digital signal
10
that is switched from off (low)
12
to on (high)
18
. When the electrical contact is activated
14
, the signal goes through a contact bounce period
16
until it eventually stabilizes.
FIG. 1B
shows an alternative graph of a contact bounce where the electrical contact is switched from on (high)
22
to off (low)
28
. As can be seen, a contact bounce period
26
occurs when the contact is de-activated
24
in a similar manner as shown in FIG.
1
A.
For devices such as a lamp or electric motor, contact bounce is not usually a problem. The contact bounce periods
16
and
26
lasts a minute fraction of a second and will not affect the performance of the device. However, if the device being used is micro-processor, contact bounce can have a significant impact on performance since these devices perform operations in microseconds.
FIG. 2
shows a schematic of a prior art embodiment of a “hot-swap” controller circuit
30
. “Hot-swapping” or “hot-plugging” refers to the insertion and removal of circuit boards into an active device, such as a computer motherboard, while the device is powered on. This circuit
30
is design to control inrush current so that an integrated circuit board can be safely inserted to and removed from a live backplane. In this embodiment, the controller circuit
30
represents the LT® 1640 Hotswap™ Controller produced by Linear Technology. Various pin connections for the chip are indicated by name in FIG.
2
. The circuit
30
combines the controller chip
32
with additional components to provide control signals
33
to the system voltage converters (not shown). The power for the circuit
30
is provided by a power supply bus that includes: a 48 V line
34
; a 48 V Return line
36
; and a Board Engage (or Ground) line
38
.
When the power supply bus is connected, the circuit may be susceptible to the problems of contact bounce. The contact bounce that results can cause an excess transient current and could potentially affect operation of the circuit
30
. However, the controller circuit
30
includes a circuit breaker (not shown) that is internal to the controller chip
32
. If the circuit
30
were to experience an excessive transient current, it would be transmitted from the GATE pin on the controller chip
32
through the output line
41
to the MOSFET
40
. The MOSFET
40
would direct the majority of the excess current to the 48 V Return line
36
. Additionally, a trace current would be transmitted back to the SENSE gate of the controller chip
32
via the trace current line
42
. Upon receipt of a trace current, the circuit breaker within the controller chip
32
will go to a “Latch Off” state which disable the circuit
30
.
SUMMARY OF INVENTION
In an alternative embodiment, the invention relates to a connection module for a hot-swappable system power supply bus comprising: a module body; a power return pin extending from the module body, the power return pin having a first length; a power supply pin extending from the module body, the power supply pin having a second length; and a system ground pin extending from the module body, the system ground pin having a third length, wherein the third length is less than the first length and the second length such that the system ground pin makes a connection with the hot-swappable system subsequent to insertion of the power return pin and the power supply pin.
In an alternative embodiment, the invention relates to a connection module for a hot-swappable system power supply bus comprising: means for connecting a power return source to the hot-swappable system; means for connecting a power supply source to the hot-swappable system; and means for connecting a ground source to the hot-swappable system such that the ground source is connected after a contact bounce period of the power supply source and a contact bounce period of the power return source.
In an alternative embodiment, the invention relates to a method for connecting a power connection module to a hot-swappable system comprising: creating an over-voltage condition in the hot-swappable system by connecting a power supply pin and a power return pin to a power supply bus; allowing a contact bounce period to elapse during the over-voltage condition; and connecting a system ground pin to the power supply bus after the contact bounce period has elapsed.
The advantages of the invention include, at least, a power connection module that prevents excessive transient current, due to contact bounce, from being detected, by creating an over-voltage condition that allows the contact bounce to terminate before the system ground is connected.


REFERENCES:
patent: 3432795 (1969-03-01), Jayne
patent: 3612985 (1971-10-01), Rockett
patent: 4118690 (1978-10-01), Paynton
patent: 5144520 (1992-09-01), Parker et al.
patent: 5268592 (1993-12-01), Bellamy et al.
patent: 5434752 (1995-07-01), Huth et al.
patent: 5584030 (1996-12-01), Husak et al.
patent: 5758764 (1998-06-01), Garoffolo et al.
patent: 5909065 (1999-06-01), Jones et al.
patent: 6099328 (2000-08-01), Nelson et al.

Affiliated with

Also associated with

Rating

Suppressing power bus bouncing in a hot-swappable system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Suppressing power bus bouncing in a hot-swappable system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Suppressing power bus bouncing in a hot-swappable system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2835027