UPD16488AP datasheet(72/91 Pages) NEC

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Data Sheet S15745EJ2V0DS

µµµµPD16488A

8. POWER SUPPLY SEQUENCE

The

µPD16488A includes power supply circuitry, such as a booster and a voltage follower. When a reset is performed

using the /RES pin, the reset function is restricted so as to prevent operation faults that may occur due to noise effects, etc.

When electric charge remains in the smoothing capacitor that is connected between the VSS pin and the voltage pins

related to the LCD driver (VLCD, VLC1 to VLC4), troubles such as a brief all-black display screen may occur when the power is

switched ON or OFF. The following power-on sequence is recommended as a means to avoid such troubles when

switching the power ON or OFF.

8.1 Power ON Sequence (When Using On-Chip Power Supply, Power Supply ON

¡ Display ON)

Turn power ON when /RES pin = L

↓

Power supply stabilization

↓

/RES pin = H

↓

Wait at least 50

µs before command input

Command reset

↓

Control register 1

DISP = 0, HALT = 1

Display OFF, internal operations stopped

↓

IC functions set via command input

• Control register 1

(DISP = 0, HALT = 1 status is retained)

• Control register 2

•••• Power control register 1

(HPM1, HPM0 = 1, 1)

• Power control registers 2, 3

• Electronic volume register

• Partial electronic volume register

• Boost adjustment register

Specification of power activation mode

↓

User-specified settings via command input

Duty setting register (R5)

AC driver inversion cycle register (R6)

Function settings for gray scale data, etc.

Make sure to set the duty setting register (R5) and AC

driver inversion cycle register (R6)

↓

Initialization complete

↓

Control register 1

DISP = 0, HALT = 0

Display OFF, internal operations started

↓

LCD display screen settings

• Display start line setting register

• Write screen data, etc. + wait time

After internal operations are started, wait at least 400 ms

before turning on the LCD display Note.

↓

Power system control register 1

(Mode except HPM1, HPM0 (1, 1))

Cancels V/F mode for power activation

↓

Control register 1

DISP = 1, HALT = 0

Display ON, internal operation start mode

Note

This 400 ms wait time varies according to the panel characteristics and the capacitance value of the

boost/smoothing capacitor. We recommend determining the wait time after making a thorough evaluation of the

actual device (refer to 8.5 VOUT, VLCD Voltage Sequence (Power ON

→

→ Power OFF)).

UPD16488AP Datasheet(PDF) 72 Page - NEC

UPD16488AP Datasheet(HTML) 72 Page - NEC

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