Browse Prior Art Database

Hot/Warm Plug-In Discrimination Circuit for PC Docking Station

IP.com Disclosure Number: IPCOM000114633D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 4 page(s) / 88K

Publishing Venue

IBM

Related People

Fukushima, A: AUTHOR [+3]

Abstract

Disclosed is a method to power-off the Notebook PC which is hot plugged in (while PC is in ACTIVE mode) to Docking Station to prevent CMOS latch-up, but not to power-off the Notebook PC which is warm plugged in (PC is in SUSPEND mode). As a most popular latch-up prevention method for hot/warm plug in, Notebook PC has a circuit to detect if Docking Station is connected or not, and when Notebook PC detects that Docking Station is connected, Notebook PC is force powered off regardless of its current state (ACTIVE or SUSPEND). But by such conventional method, even suspended Notebook PC is powered off, and customers who plugged in suspended Notebook PC to Docking Station by mistake had to re-boot the Notebook PC. It is sometimes difficult for customers to distinguish between SUSPENDED notebook PC and POWERED-OFF notebook PC.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Hot/Warm Plug-In Discrimination Circuit for PC Docking Station

      Disclosed is a method to power-off the Notebook PC which is hot
plugged in (while PC is in ACTIVE mode) to Docking Station to prevent
CMOS latch-up, but not to power-off the Notebook PC which is warm
plugged in (PC is in SUSPEND mode).  As a most popular latch-up
prevention method for hot/warm plug in, Notebook PC has a circuit to
detect if Docking Station is connected or not, and when Notebook PC
detects that Docking Station is connected, Notebook PC is force
powered off regardless of its current state (ACTIVE or SUSPEND).  But
by such conventional method, even suspended Notebook PC is powered
off, and customers who plugged in suspended Notebook PC to Docking
Station by mistake had to re-boot the Notebook PC.  It is sometimes
difficult for customers to distinguish between SUSPENDED notebook PC
and POWERED-OFF notebook PC.  So, it often happens that some
customers plug in SUSPENDED notebook PC to Docking Station.  By the
subject invention, SUSPENDED Notebook PC is still in SUSPEND mode
when connected to Docking Station by mistake and can resume after
plugging out of the Docking Station.  Also, Docking Station can have
the circuit to warn the suspended Notebook PC which is connected.
Fig. 1 shows the configuration when Notebook PC and Docking Station
is connected.  Notebook PC has the circuit that implements the
subject invention.

Where:
  1.  PWR_OFF# signal:
      Pulled up in Notebook PC side and pulled down in Docking side.
       When Docking Station is connected to Notebook PC, Notebook PC
can
       detect that Docking Station is connected.  These two signals
are
       assigned at the longer edge pin of the external connector and
      ...