HD6413008VF25 Datasheet, PDF (495/688 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

17. Clock Pulse Generator
17.2 Oscillator Circuit
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock
signal.
17.2.1 Connecting a Crystal Resonator
Circuit Configuration: A crystal resonator can be connected as in the example in figure 17.2.
Damping resistance Rd should be selected according to table 17.1 (1), and external capacitances
C_L1 and C_L2 according to table 17.1 (2). An AT-cut parallel-resonance crystal should be used.
C_L1
EXTAL
XTAL
Rd
C_L2
Figure 17.2 Connection of Crystal Resonator (Example)
If a crystal resonator with a frequency higher than 20 MHz is connected, the external load
capacitance values in table 17.1 (2) should not exceed 10 [pF]. Also, in order to improve the
accuracy of the oscillation frequency, a thorough study of oscillation matching evaluation, etc.,
should be carried out when deciding the circuit constants.
Table 17.1 (1) Damping Resistance Value
Damping
Resistance
Value
2
Frequency f (MHz)
2 < f ≤ 4 4 < f ≤8 8 < f ≤ 10 10 < f ≤ 13 13 < f ≤ 16 16 < f ≤ 18 18 < f ≤ 25
Rd (Ω)
1 k 500
200
0
0
0
0
0
Note: A crystal resonator between 2 MHz and 25 MHz can be used. If the chip is to be operated
at less than 2 MHz, the on-chip frequency divider should be used. (A crystal resonator of
less than 2 MHz cannot be used.)
Rev.4.00 Aug. 20, 2007 Page 449 of 638
REJ09B0395-0400