Osc3 Oscillator - Epson S1C17704 Technical Manual

7 OSCILLATOR (OSC)

7.2 OSC3 Oscillator

The OSC3 oscillator generates the main clock (Max. 8.2 MHz) for operating the S1C17 Core and peripheral
circuits at high speed. Depending on the product number, the oscillator type is crystal/ceramic oscillation (Max. 8.2
MHz) or CR oscillation (Max. 2.2 MHz).
Figure 7.2.1 shows the structure of the OSC3 oscillator circuit.
C
C
R
CR3
When the crystal/ceramic oscillator model is selected, connect a crystal (X'tal3) or ceramic resonator (Ceramic)
and a feedback resistor (R
OSC4 pins and V .
SS
When the CR oscillator model is selected, connect only a resistor (R
Controlling the OSC3 oscillation on and off
Setting OSC3EN (D0/OSC_CTL register) to 0 causes the OSC3 oscillator circuit to stop; setting it to 1 causes
the OSC3 oscillator circuit to start oscillating. Also the OSC3 oscillator circuit stops when the S1C17 Core
enters SLEEP mode.
∗ OSC3EN: OSC3 Enable Bit in the Oscillation Control (OSC_CTL) Register (D0/0x5061)
At initial reset, OSC3EN is set to 1 for enabling OSC3 oscillation. Furthermore, the OSC3 clock is selected as
the system clock, so the S1C17 Core starts operating with the OSC3 clock.
7-2
Table 7.2.1 Lineup
Model No.
S1C17704F00B100
S1C17704F00E100
G3 OSC3
X'tal3
R
or
f
Ceramic
OSC4
D3
V
SS
(1) Crystal/ceramic oscillator circuit
OSC3
OSC4
(2) CR oscillator circuit
Figure 7.2.1 OSC3 Oscillator Circuit
) between the OSC3 and OSC4 pins, and two capacitors (C
f
Main (OSC3) oscillator
Crystal/Ceramic
CR
f
OSC3
Oscillator control signal
SLEEP status
Oscillator control signal
SLEEP status
) between the OSC3 and OSC4 pins.
CR3
EPSON
f
OSC3
, C ) to the OSC3 and
G3 D3
S1C17704 TECHNICAL MANUAL