ZEUS Technical Manual

Detailed hardware description

 

 

LCD logic and backlight power

The display signals are +3.3V compatible. The ZEUS contains power control circuitry for the flat panel logic supply and backlight supply. The flat panel logic is supplied with a switched 3.3V (default) or 5V supply (for details see the section JP3 – LCD logic supply selection, page 94). The backlight is supplied with a switched 5V supply for the inverter.

The power switches (TPS2033D) for flat panel logic and backlight have the current- limiting (1.5A) and thermal protection features which eliminates the need for the fuses.

The PXA270 GPIO101 pin (LCDEN signal) controls the supply voltage to the LCD display.

LCDEN

 

(CPU_GPIO101)Selected LCD function

0

LCD power off (default)

1

LCD power On

 

 

The PXA270 GPIO19 pin (BKLEN signal) controls the supply voltage to the backlight inverter:

BKLEN

 

(CPU_GPIO19)Selected backlight function

0

BKLSAFE Power Off (Default)

1

BKLSAFE 5V Power On

 

 

The BKLEN signal is also routed to the connector J14. See the section J14 – LCD connector, page 85, for J14 pin assignment and connector details.

Signals BKLEN and BKLSAFE are also routed to the connector J24. See the section J24 – Backlight power, page 92, for further details.

Typically the power up sequence is as follows (please check the datasheet for the particular panel in use):

1Enable display power.

2Enable flat panel interface.

3Enable backlight.

Power down is in reverse order.

© 2007 Eurotech Ltd Issue D

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