4507_M Datasheet, PDF (164/216 Pages) Renesas Technology Corp – 4-BIT CISC SINGLE-CHIP MICROCOMPUTER 4500 SERIES

4507 Group
APPLICATION
2.7 Oscillation circuit
(3) Ceramic resonator
When the ceramic resonator is used as the
source oscillation (f(XIN)), connect the ceramic
resonator and the external circuit to pins XIN
and XOUT at the shortest distance. Then,
execute the CMCK instruction. A feedback
resistor is built in between pins XIN and XOUT
(Figure 2.7.3).
As for the oscillation frequency, do not exceed
the values shown in the Table 2.7.1.
XIN
CI N
Execute the CMCK instruction in
program.
4507
Note: Externally connect a damping
XOUT
resistor Rd depending on the
oscillation frequency.
(A feedback resistor is built-in.)
Rd
Use the resonator manu-
facturer’s recommended value
COUT
because constants such as
capacitance depend on the
resonator.
Fig. 2.7.3 Ceramic resonator external circuit
Table 2.7.1 Maximum value of oscillation frequency and supply voltage
Supply voltage
(System clock)
Oscillation frequency
2.7 V to 5.5 V
(f(XIN)) High-speed mode
4.4 MHz
2.0 V to 5.5 V
(f(XIN)) High-speed mode
2.2 MHz
(f(XIN)/2) Middle-speed mode
4.4 MHz
(f(XIN)/4) Low-speed mode
(f(XIN)/8) Default mode
(4) RC oscillation
When the RC oscillation is used as the source
oscillation (f(XIN)), connect the XIN pin to the
external circuit of resistor R and the capacitor
C at the shortest distance and leave XOUT
pin open. Then, execute the CRCK instruction
(Figure 2.7.4).
R
The frequency is affected by a capacitor, a
resistor and a microcomputer.
C
So, set the constants within the range of the
frequency limits.
4507
* ^{Execute the CRCK}
instruction in program.
XIN
XOUT
Fig. 2.7.4 External RC oscillation circuit
Rev.2.01 Feb 04, 2005
REJ09B0195-0201
2-49