Hot plug device providing turn on FETs with a softstart capability

Patent metadata

Field	Value
Publication number	US-9853444-B2
Application number	US-201514831312-A
Country	US
Kind code	B2
Filing date	Aug 20, 2015
Priority date	Apr 18, 2014
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A method of controlling the inrush current to a hot plug device. The method includes directing current from an input power rail of the hot plug device to an output power rail of the hot plug device through a high impedance auxiliary current path, wherein an electronic subsystem of the hot plug device is coupled to the output power rail. The method further includes allowing current from the input power rail to pass through a plurality of main turn on FETs to the output power rail in response to the output power rail having a voltage that exceeds a voltage threshold as a result of directing current through the high impedance auxiliary current path.

First claim

What is claimed is:

1. A method of controlling the inrush current to a hot plug device, comprising:
directing current from an input power rail of the hot plug device to an output power rail of the hot plug device through a high impedance auxiliary current path, wherein an electronic subsystem of the hot plug device is coupled to the output power rail; and
allowing current from the input power rail to pass through a plurality of main turn on FETs to the output power rail in response to the output power rail having a voltage that exceeds a voltage threshold as a result of directing current through the high impedance auxiliary current path.

2. The method of claim 1 , further comprising:
preventing current from the input power rail passing to the output power rail in response to the voltage of the output power rail failing to exceed the voltage threshold during a timeout period after initially directing current through the high impedance auxiliary current path.

3. The method of claim 1 , wherein the high impedance auxiliary current path includes a fuse, an impedance element and an auxiliary turn on FET.

4. The method of claim 3 , further comprising:
a turn on controller monitoring the voltage on the output power rail, wherein directing current through the high impedance auxiliary current path includes the turn on controller sending a turn on signal to the auxiliary turn on FET, and wherein allowing current to pass through a plurality of main turn on FETs includes the turn on controller sending a turn on signal to the plurality of main turn on FETs.

5. The method of claim 1 , wherein each main turn on FET includes a gate, a power input for coupling to the input power rail, and an output coupled to the output power rail.

6. The method of claim 1 , further comprising:
coupling the input power rail to a 12 volt power source.

7. The method of claim 1 , further comprising:
connecting the hot plug device to a host system so that the turn on controller is in communication with a system controller of the host system and the input power rail is in communication with a power source of the host system.

8. The method of claim 1 , wherein the electronic subsystem is selected from a graphics processing subsystem, a memory subsystem, and a network interface subsystem.

Assignees

• IBM

Inventors

• Barnette Jamaica L
• Celenza Nicholas
• Totten Brian C

Classifications

• G06F1/266

  Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips · CPC title

• H02H9/025

  Current limitation using field effect transistors · CPC title

• G06F13/4081 Primary

  Live connection to bus, e.g. hot-plugging (current or voltage limitation during live insertion H02H9/004) · CPC title

• H02H7/20 Primary

  for electronic equipment (for converters H02H7/10; for electric measuring instruments G01R1/36; for DC voltage or current semiconductor regulators G05F1/569; for amplifiers H03F1/52; for electronic switching circuits H03K17/08) · CPC title

• H02H9/004

  in connection with live-insertion of plug-in units (involving communication with a central processing unit G06F13/40) · CPC title