2 POWER SUPPLY, RESET, AND CLOCKS
2-6
Seiko epson Corporation
S1C17F13 TeChniCal Manual
(Rev. 1.0)
Input/Output Pins
2.3.2
Table 2.3.2.1 lists the CLG pins.
3.2.1 List of CLG Pins
Table 2.
Pin name
I/O
*
Initial status
*
Function
OSC1
A
–
OSC1A oscillator circuit input
OSC2
A
–
OSC1A oscillator circuit output
OSC3
A
–
OSC3A oscillator circuit input
OSC4
A
–
OSC3A oscillator circuit output
EXOSC
I
I
EXOSC clock input
FOUT
O
O (L)
FOUT clock output
*
Indicates the status when the pin is configured for CLG.
If the port is shared with the CLG input/output function and other functions, the CLG function must be assigned to
the port. For more information, refer to the “I/O Ports” chapter.
Clock Sources
2.3.3
OSC3B oscillator circuit
The OSC3B oscillator circuit features a fast startup and no external parts are required for oscillating. Figure
2.3.3.1 shows the configuration of the OSC3B oscillator circuit.
OSC3B oscillator circuit
Inter
nal data
bu
s
OSC3BEN
Clock
oscillator
Oscillation
stabilization
waiting circuit
Interrupt
control circuit
OSC3BSTAIE
OSC3BSTAIF
Interrupt
controller
OSC3BCLK
OSC3BFREQ[1:0]
3.3.1 OSC3B Oscillator Circuit Configuration
Figure 2.
The OSC3B oscillator circuit output clock OSC3BCLK is used as SYSCLK at booting.
The OSC3BCLK frequency can be selected using the CLGOSC3B.OSC3BFREQ[1:0] bits.
For more information on the oscillation characteristics, refer to “OSC3B oscillator circuit characteristics” in the
“Electrical Characteristics” chapter.
OSC3A oscillator circuit
The OSC3A oscillator circuit is a high-speed oscillator circuit that uses a crystal or ceramic resonator. Figure
2.3.3.2 shows the configuration of the OSC3A oscillator circuit.
OSC3A oscillator circuit
Gain-
controlled
oscillation
inverter
Feedback
resistor R
F3
Drain resistor R
D3
OSC3AEN
Oscillation
stabilization
waiting circuit
Noise filter
Interrupt
control circuit
INVN[1:0]
OSC3AWT[1:0]
OSC3
OSC4
Interrupt
controller
OSC3ACLK
X’tal3/
Ceramic3
Inter
nal data
bu
s
OSC3ASTAIE
OSC3ASTAIF
V
SS
V
DD
V
DD
V
SS
Gate capacitor
C
G3
Drain capacitor
C
D3
3.3.2 OSC3A Oscillator Circuit Configuration
Figure 2.
A crystal resonator (X’tal3) or ceramic resonator (Ceramic3) should be connected between the OSC3 and OSC4
pins. Additionally, two capacitors (C
G3
and C
D3
) should be connected between the OSC3/OSC4 pins and V
SS
.
The embedded gain-controlled oscillation inverter allows selection of the resonator from a wide frequency range.
For the recommended parts and the oscillation characteristics, refer to the “Basic External Connection Diagram”
chapter and “OSC3A oscillator circuit characteristics” in the “Electrical Characteristics” chapter, respectively.