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A Method of Selectable Power Supply for LCD Panel

IP.com Disclosure Number: IPCOM000123265D
Original Publication Date: 1998-Aug-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Horikoshi, H: AUTHOR [+3]

Abstract

Disclosed is a control method of selectable power supply. This method provides the power supply selection for LCD panel from DC/DC power circuit by using only one pair of power and GND line. LCD has its own LCD ID. IF LCD needs 5V, its ID should select 5V, which means that LCDSEL5V and "-PANEL OFF" are set to "H". Then VccP outputs 5V to LCD panel.

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A Method of Selectable Power Supply for LCD Panel

   Disclosed is a control method of selectable power
supply.  This method provides the power supply selection for LCD
panel from DC/DC power circuit by using only one pair of power and
GND line.  LCD has its own LCD ID.  IF LCD needs 5V, its ID should
select 5V, which means that LCDSEL5V and "-PANEL OFF" are set to "H".
Then VccP outputs 5V to LCD panel.

   The selected power voltage, 5V or 3.3V or any other (?)
voltages, can be supplied to LCD panel by only one pair of power and
GND line.

   This method saves the number of power pins of LCD interface
connector and the number of power lines to be wired to the LCD
interface connector.

   Fig.1 shows the control circuit.  VccP is the interface
power signal for LCD panel.  The following table shows the VccP
output voltage status.  LCD has its ID to tell the system what
voltage it uses.  For example, when LCD needs 5V, it has LCD ID5 then
VccP outputs 5V to LCD.  If LCD needs 3.3V, it has LCD ID3 then VccP
outputs 3.3V to LCD.  So, if LCD needs ?V, it has LCD ID? then VccP
outputs ?V to LCD panel.