VL-PS-PDA320240D-02 REV. A
(PDA320240D-02)
JUN/2005
PAGE 14 OF 16
4.4 Precaution when Connecting and Disconnecting the Power
Be careful when connecting or disconnecting the power.
This LSI has a high-voltage LCD driver, so it may be permanently damaged by a high current,
which may occur, if a voltage is supplied to the LCD driver power supply while the logic system
power supply is floating.
The details are as follows:
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When connecting the power supply, connect the LCD driver power after connecting the logic
system power. Furthermore, when disconnecting the power, disconnect the logic system power
after disconnecting the LCD driver power.
We recommend that you connect a serial resistor (50-100 Ω) or fuse to the LCD driver power V0
of the system as a current limiting device. Also, set a suitable value of the resistor in
consideration of LCD display grade.
In addition, when connecting the logic power supply, the logic condition of this LSI inside is
insecure. Therefore connect the LCD driver power supply after resetting the logic condition of
this LSI inside on /DOFF function. After that, the /DOFF cancel the function after the LCD
driver power supply has become stable. Furthermore, when disconnecting the power, set the
LCD driver output pins to level VSS on the /DOFF function. After that, disconnect the logic
system power after disconnecting the LCD driver power.
When connecting the power supply, follow the recommended sequence shown.
Figure 4: Power sequence
VARITRONIX [ VARITRONIX INTERNATIONAL LIMITED ]
