Osc3 Oscillation Circuit; Switching The Cpu Clock - Epson S1C63003 Technical Manual

7 OSCillaTiOn CiRCuiT anD ClOCK COnTROl
7.1.4

OSC3 Oscillation Circuit

The OSC3 oscillation circuit generates the system clock to run the CPU and some peripheral circuits at high speed.
This oscillation circuit stops when the SLP instruction is executed or the OSCC register is set to "0."
In the S1C63004/008/016, the oscillator type can be selected from ceramic, CR (external R), and CR (built-in R) by
mask option. The S1C63003 OSC3 oscillator type is fixed at CR oscillation (built-in R).
Figure 7.1.4.1 shows the configuration of the OSC3 oscillation circuit.
When ceramic oscillation circuit is selected, connect a ceramic resonator (Ceramic) between the OSC3 and OSC4
terminals and connecting two capacitors (C
terminal and V , respectively.
SS
When CR (external R) is selected, connect a resistor (R
The CR (built-in R) oscillator does not need any external elements. Leave the OSC3 and OSC4 terminals open.
Oscillator type
Ceramic
CR (external R)
CR (built-in R)
7.2

Switching the CPu Clock

Either the OSC1 clock or the OSC3 clock can be selected as the CPU system clock using the CLKCHG register.
The OSC3 oscillation circuit can be turned off (OSCC = "0") to save power while the CPU is operating with the OSC1
clock (CLKCHG = "0").
If the system needs high speed operation, turn the OSC3 oscillation circuit on (OSCC = "1") and switch over the
system clock to OSC3 (CLKCHG = "0" → "1").
7-2
C
G3 OSC3
Ceramic
R
f
OSC4
C
D3
V
SS
(1) Ceramic oscillation circuit – S1C63004/008/016
OSC3
R
CR
OSC4
(2) CR oscillation circuit (external R) – S1C63004/008/016
R
CR
(3) CR oscillation circuit (built-in R) – S1C63003/004/008/016
Figure 7. 1.4.1 OSC3 oscillation circuit
, C ) between the OSC3 terminal and V
G3 D3
Table 7. 1.4.1 OSC3 oscillation frequency
S1C63004/008/016
Typ. 4.0 MHz (3 V normal type) or
Typ. 1.0 MHz (1.5 V low-voltage type)
Typ. 1.8 MHz (3 V normal type) or
Typ. 500 kHz (1.5 V low-voltage type)
Typ. 500 kHz (3 V normal type) or
Typ. 500 kHz (1.5 V low-voltage type)
Seiko epson Corporation
f
OSC3
Oscillation circuit
control signal
SLEEP status
f
OSC3
Oscillation circuit
control signal
SLEEP status
f
OSC3
Oscillation circuit
control signal
SLEEP status
) between the OSC3 and OSC4 terminals.
CR
Oscillation frequency
Typ. 550 kHz (3 V normal type) or
Typ. 550 kHz (1.5 V low-voltage type)
S1C63003/004/008/016 TeChniCal Manual
, and between the OSC4
SS
S1C63003
–
–
(Rev. 1.1)