2 POWER SUPPLY, RESET, AND CLOCKS
S1C17F13 TeChniCal Manual
Seiko epson Corporation
2-7
(Rev. 1.0)
OSC1 oscillator circuit
OSC1 is a low-power oscillator circuit that generates the timer operating clock and the system clock for low-
speed operations. The OSC1 oscillator circuit consists of two oscillators, OSC1A and OSC1B, and the oscilla-
tor to be used should be selected using the CLGOSC1.OSC1SEL bit. Figure 2.3.3.3 shows the configuration of
the OSC1 oscillator circuit.
OSC1A oscillator circuit
OSC1 oscillator circuit
External gate
capacitor C
G1
Internal
gate capacitor C
GI1
Feedback
resistor R
F1
Drain
resistor R
D1
External drain
capacitor C
D1
Internal
drain capacitor C
DI1
V
SS
V
SS
OSC1EN
Oscillation
stabilization
waiting circuit
Interrupt
control circuit
OSC1WT[1:0]
OSC1WT[1:0]
OSC1
OSC2
X’tal1
OSC1STAIE
OSC1STAIF
Interrupt
controller
OSC1CLK
Inter
nal data
bu
s
OSC1B oscillator circuit
Clock
oscillator
Oscillation
stabilization
waiting circuit
OSC1BCLK
OSC1ACLK
OSC1SEL
Regulated
clock
generation
V
SS
V
DD
V
DD
V
SS
3.3.3 OSC1 Oscillator Circuit Configuration
Figure 2.
OSC1A oscillator circuit
The OSC1A oscillator circuit is a high-precision and low-power oscillator circuit that uses a 32.768 kHz
crystal resonator. A crystal resonator (X’tal1) should be connected between the OSC1 and OSC2 pins. Ad-
ditionally, two capacitors (C
G1
and C
D1
) should be connected between the OSC1/OSC2 pins and V
SS
. For
the recommended parts and the oscillation characteristics, refer to the “Basic External Connection Dia-
gram” chapter and “OSC1A oscillator circuit characteristics” in the “Electrical Characteristics” chapter,
respectively.
OSC1B oscillator circuit
The OSC1B oscillator circuit generates about 32 kHz clock without external components.
EXOSC clock input
EXOSC is an external clock input circuit that supports square wave and sine wave clocks. Figure 2.3.3.4 shows
the configuration of the EXOSC clock input circuit.
EXOSC clock
input circuit
Input control
circuit
EXOSCEN
EXOSC
EXOSCCLK
Inter
nal data
bu
s
3.3.4 EXOSC Clock Input Circuit
Figure 2.
EXOSC has no oscillation stabilization waiting circuit included, therefore, it must be enabled when a stabilized
clock is being supplied. For the input clock characteristics, refer to “EXOSC external clock input characteris-
tics” in the “Electrical Characteristics” chapter.