Epson S1C63454, Техническое руководство

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8
EPSON
S1C63454 TECHNICAL MANUAL
CHAPTER 2: POWER SUPPLY AND INITIAL RESET
2.1.1 Voltage <V
D1
> for oscillation circuit and internal circuits
V
D1
is a voltage for the oscillation circuit and the internal logic circuits, and is generated by the oscillation
system voltage regulator for stabilizing the oscillation.
The S1C63454 is designed with twin clock specification; it has two types of oscillation circuits OSC1 and
OSC3 built-in. Use OSC1 clock for normal operation, and switch it to OSC3 by the software when high-
speed operation is necessary. When switching the clock, the operating voltage V
D1
must be switched by
the software to stabilize the operation of the oscillation circuit and internal circuits.
The oscillation system voltage regulator can output the following two types of V
D1
voltage. It should be
set at the value according to the oscillation circuit and oscillation frequency by the software.
Single clock operation (OSC1 crystal oscillation): V
D1
= 1.3 V
Single clock operation (OSC1 CR oscillation): V
D1
= 2.2 V
Twin clock operation (OSC3, 4 MHz): V
D1
= 2.2 V
Refer to Section 4.3, "Oscillation Circuit", for the V
D1
switching procedure.
However, since the V
D1
voltage value is fixed at 2.2 V when the CR oscillation circuit has been selected as
the OSC1 oscillation circuit by mask option, it is not necessary to switch V
D1
by software.
2.1.2 Voltage <V
C1
–V
C5
> for LCD driving
V
C1
–V
C5
are the LCD drive voltages for which either the voltage generated by the LCD system voltage
circuit or voltage to be supplied from outside can be used. The built-in LCD system voltage circuit
generates four voltages (1/4 bias) V
C1
, V
C2
, V
C4
and V
C5
(excluding V
C3
). These four output voltages can
only be supplied to the externally expanded LCD driver.
When external voltages are supplied, 1/5 bias driving can be done by inputting drive voltage to the V
C1
–
V
C5
terminals (including V
C3
).
Either the internal generated voltages or external voltages used for the LCD drive voltage can be selected
by a mask option.
The LCD system voltage circuit generates V
C1
or V
C2
with the voltage regulator built-in, and generates
three other voltages by boosting or reducing the voltage of V
C1
or V
C2
. Table 2.1.2.1 shows the V
C1
, V
C2
,
V
C4
and V
C5
voltage values and boost/reduce status.
Table 2.1.2.1 LCD drive voltage when generated internally
LCD drive voltage
V
C1
(0.975–1.2 V)
V
C2
(1.950–2.4 V)
V
C4
(2.925–3.6 V)
V
C5
(3.900–4.8 V)
V
DD
= 1.8–6.4 V
V
C1
(standard)
2
×
V
C1
3
×
V
C1
4
×
V
C1
V
DD
= 2.6–6.4 V
1/2
×
V
C2
V
C2
(standard)
3/2
×
V
C2
2
×
V
C2
Note: The LCD drive voltage can be adjusted by the software (see Section 4.7.6). Values in the above
table are typical values.
Either the V
C1
or V
C2
used for the standard is selected according to the supply voltage by the software.
The V
C2
standard improves the display quality and reduces current consumption, however, the power
supply voltage V
DD
must be 2.6 V or more.
Refer to Section 4.7, "LCD Driver", for control of the LCD drive voltage.