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CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Oscillation Circuit)
4.3 Oscillation Circuit
4.3.1 Configuration of oscillation circuit
The E0C6006 has two oscillation circuits (OSC1 and OSC3). OSC1 is a crystal oscillation circuit that
supplies the operating clock to the CPU and peripheral circuits. OSC3 is either a CR or a ceramic oscilla-
tion circuit. When processing with the E0C6006 requires high-speed operation, the CPU operating clock
can be switched from OSC1 to OSC3 by the software. Figure 4.3.1.1 is the block diagram of this oscillation
system.
OSC1
oscillation circuit
OSC3
oscillation circuit
4.3.2 OSC1 oscillation circuit
The OSC1 crystal oscillation circuit generates the main clock for the CPU and the peripheral circuits. The
oscillation frequency is 32.768 kHz (Typ.). Figure 4.3.2.1 is the block diagram of the OSC1 oscillation
circuit.
As shown in Figure 4.3.2.1, the crystal oscillation circuit can be configured simply by connecting the
crystal oscillator (X'tal) of 32.768 kHz (Typ.) between the OSC1 and OSC2 terminals and the trimmer
capacitor (C
) between the OSC1 and V
GX
4.3.3 OSC3 oscillation circuit
The E0C6006 has built-in the OSC3 oscillation circuit that generates the CPU's sub-clock (Typ. 455 kHz)
for high speed operation and the source clock for peripheral circuits needing a high speed clock (REM
circuit). The mask option enables selection of either the CR or ceramic oscillation circuit. When CR
oscillation is selected, only a resistance is required as an external element. When ceramic oscillation is
selected, a ceramic oscillator and two capacitors (gate and drain capacitance) are required.
Figure 4.3.3.1 is the block diagram of the OSC3 oscillation circuit.
12
Fig. 4.3.1.1 Oscillation system block diagram
V
DD
OSC1
C
GX
X'tal
OSC2
Fig. 4.3.2.1 OSC1 oscillation circuit (crystal)
terminals.
DD
OSC3
OSC4
(a) CR oscillation circuit
Divider
To peripheral circuits
Clock
To CPU
switch
CPU clock selection signal
Oscillation circuit control signal
To CPU and
peripheral circuits
V
DD
C
DX
C
CR
To CPU and
REM circuit
OSCC
EPSON
E0C6006 TECHNICAL MANUAL
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