Epson S1C63358, Техническое руководство

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S1C63358 TECHNICAL MANUAL
EPSON
9
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 S1C63358 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
= 1.35 V
Single clock operation (OSC1 CR oscillation): V
D1
= 2.25 V
Twin clock operation (OSC3, 4 MHz): V
D1
= 2.25 V
Refer to Section 4.4, "Oscillation Circuit", for the V
D1
switching procedure.
However, since the V
D1
voltage value is fixed at 2.25 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
C3
> for LCD driving
V
C1
to V
C3
are the voltages for LCD drive, and are generated by the LCD system voltage circuit to
stabilize the display quality.
The LCD system voltage circuit generates V
C1
with the voltage regulator built-in, and generates two
other voltages by boosting the voltage of V
C1
(V
C2
= 2 • V
C1
, V
C3
= 3 • V
C1
). When 1/2 bias is selected by
mask option, V
C2
becomes the same level with V
C1
. (V
C2
= V
C1
, V
C3
= 2 • V
C1
).
1.4 V or more voltage is needed to generate the voltage V
C1
.
Therefore, when operating with 0.9–1.4 V, the LCD display contrast will become worse.
Refer to Chapter 7, "Electrical Characteristics", for voltage values of V
C1
to V
C3
.
2.1.3 Voltage source for oscillation system voltage regulator
(1) Booster mode (V
C2
mode)
The S1C63358 operates with 0.9–3.6 V supply voltage. However, a minimum 1.4 V supply voltage
during single clock operation (OSC1) or a minimum 2.3 V during twin clock operation (OSC3, 4 MHz)
is needed for the oscillation system voltage regulator. Therefore, when operating with the following
supply voltage (V
DD
), switch the power supply source to drive the oscillation system regulated
voltage circuit with the V
C2
.
• During single clock operation (OSC1): V
DD
= 0.9–1.4 V (V
C2
= 1.8–2.1 V)
When the supply voltage is more than needed for operation, do not set in this mode because the V
C2
power source will increases current consumption to the oscillation system voltage regulator.
Note: Set the booster mode when a supply voltage drop is detected by the SVD circuit, such as during
heavy load operation (driving buzzer or lamp) or by battery life. (
∗
)
(2) Normal mode
In this mode, the internal power circuit directly operates by the power supply voltage V
DD
within the
range of 1.4–3.6 V (2.3–3.6 V when the OSC3 clock is used) without changing the power source (V
D1
regulator) to V
C2
. At initial reset, this mode is set.
When the supply voltage V
DD
is within the range of 1.4–3.6 V, don't change the power source (V
D1
regulator) to V
C2
(VDSEL = "1"), otherwise it will cause malfunction.