PCF8833 View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
'PCF8833' PDF : 112 Pages View PDF
Philips Semiconductors
STN RGB - 132 × 132 × 3 driver
Objective speciï¬cation
PCF8833
6.2.5 BOOSTER VOLTAGE ON
The LCD supply generation circuits will be switched on
when the Booster voltage on (BSTRON) command is sent.
The BSTRON command has a direct effect only when the
PCF8833 is not in Power-down mode (Sleep_OUT is not
active).
With a reset DISPON (see Section 6.2.18) and BSTRON
are set, the PCF8833 will start-up with Sleep_OUT (see
Section 6.2.7) following the built-in start-up sequence
which generates the requested voltages and switches on
the display, unless DISPOFF and/or BSTROFF was sent.
When the LCD supply generation circuits are switched on,
it is necessary to wait for a certain time before the power
circuits become stable and the display can be switched on.
Because this time is dependent on the required VLCD
voltage, the external components used, the applied supply
voltage and some other parameters, the PCF8833
monitors the LCD supply generation circuit internally and
will only switch-on the display when the LCD supply
generation circuits are stable.
The status of the LCD supply generation circuits can be
monitored with the read display status (RDDST)
command; see Section 6.2.7.
Figure 3 shows two sequences for using the BSTRON
command, assuming BSTROFF and DISPOFF were set
before sending Sleep_OUT. In sequence A the command
to switch the display on (DISPON) is sent to the PCF8833
before the BSTRON command is sent. Therefore the
display will only be switched on when the LCD supply
generation circuit generates a stable VLCD. In sequence B
the RDDST command is used to monitor the LCD supply
generation circuit and, after the D31 bit of the RDDST is
set to logic 1, the DISPON command will be sent;
see Section 6.2.7.
For the effect of possible combinations of commands
Sleep_IN/Sleep_OUT and BSTRON/BSTROFF; see
Table 17 and Fig.4. Figure 7 shows the effects of the
combination of commands BSTRON and BSTROFF with
DISPON and DISPOFF.
Table 7 Booster voltage on register bits
D/C
7
6
5
4
3
2
1
0
DEFAULT
0
0
0
0
0
0
0
1
1
03H
handbook, full pagewidth
start
start
send Sleep_OUT 11H
send Sleep_OUT 11H
send DISPON 29H
send BISTRON 03H
send BSTRON 03H
LCD will be switched on
when LCD supply
generation circuit
is stable
monitor D[31]
RDDST 09H
D31 = 0
D31 = 1
send DISPON 29H
end
sequence A
end
sequence B
MGU912
Fig.3 Booster voltage on flow charts.
2003 Feb 14
16
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