PCF8833USLASH2DA datasheet(16/112 Pages) PHILIPS

16 / 112 page

2003 Feb 14

Philips Semiconductors

Objective speciﬁcation

STN RGB - 132

× 132 × 3 driver

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

76543210

DEFAULT

000000011

03H

handbook, full pagewidth

MGU912

send Sleep_OUT 11H

monitor D[31]

RDDST 09H

start

end

send DISPON 29H

send BSTRON 03H

LCD will be switched on

when LCD supply

generation circuit

is stable

send Sleep_OUT 11H

start

end

send BISTRON 03H

send DISPON 29H

D31 = 1

D31 = 0

sequence A

sequence B

Fig.3 Booster voltage on flow charts.

PCF8833U/2DA 数据表(PDF) 16 Page - NXP Semiconductors

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