Backlight Signals; Figure 2. Power Sequencing; Figure 3. V L Supply Dropouts; Table 7. Backlight Signal Dc Characteristics - Planar LC640.480.33-AC Operation Manual

Figure 2. Power Sequencing.

Vcc
4.5V
data
2.7V
t1 t2
Applying video signals before V
to remain "on" for a long period of time after video signals are removed—which stops
the cell scanning—may produce a latent image. In addition, there is a restriction
regarding dropouts on the V
related to the reset circuit for the LCD's internal logic. If a dip in V
duration or V falls below 2.7 Vdc then the power sequencing procedure should be
L
followed.
Figure 3. V Supply Dropouts.
L
td

Backlight Signals

The dimming control and /DISABL inputs are analog, though the latter is intended to be
driven from either an open collector device or CMOS logic. The /ABCOFF input is a
CMOS-compatible digital input.

Table 7. Backlight Signal DC Characteristics.

Description
Absolute max. input voltage
Dimming input voltage range
Recommended pot. value
RLUM HI source current
/ABCOFF input
/DISABL input
Note: Incorrect operation of the undervoltage lockout (UVLO) circuit may occur if
the /DISABL input is allowed to operate between V
4.5V
where: t
t3
is applied may cause a latchup condition. Allowing V
L
supply as illustrated in Figure 3 ("Vcc"= V
L
Vcc
where:
4.5V
2.7V
Min Max
-0.3 +5.3
0 +5.0
10 100
– 600
+3.6 +5.0
0 +1.4
– 0.5
+4.5 +5.0
0 +1.0
– 1.3
ILD
LC640.480.33-AC Operations Manual (OM600-01)
10ms
1
0< t 10ms
2
0< t 1s
3
). This is
L
exceeds 10 ms in
L
t 10ms
d
Units Symbol
Vdc V
IMAX
Vdc V
RLUM
K ohm RLUM
µA I
RLUM
Vdc V
IHA
Vdc V
ILA
mA I
ILA
Vdc V
IHD
Vdc V
ILD
mA I
ILD
and V .
IHD
L
9