E202075_HD404889 Datasheet, PDF (67/202 Pages) Renesas Technology Corp – Low-Voltage AS Microcomputers with On-Chip LCD Circuit

HD404889/HD404899/HD404878/HD404868 Series
Table 21 Oscillator Circuit Examples
External clock
operation
Circuit Structure
External
oscillator
OSC1
Circuit Constants
Open OSC2
Ceramic oscillator
C1
(OSC₁, OSC₂)
OSC1
Ceramic
oscillator
Rf _OSC2
C2
GND
Crystal oscillator
(OSC₁, OSC₂)
C1
Crystal
OSC1
oscillator
Rf _OSC2
C2
GND
Ceramic oscillator: CSA4.00MG (Murata)
R_f=1MΩ±20%
C₁=C₂=30pF±20%
R_f=1MΩ±20%
C₁=C₂=10–22pF±20%
Crystal: Equivalent circuit at left
C₀=7pFmax.
R_S=100Ωmax.
OSC1
L CS RS
Crystal oscillator
(X1, X2)
C1
Crystal
oscillator
C2
GND
L
C0
X1
X2
CS RS
OSC2
Crystal: 32.768 kHz: MX38T (Nihon Denpa
Kogyo)
C₁=C₂=20pF±20%
R_S=14kΩ
C₀=1.5pF
X1
X2
C0
Notes: 1. With a crystal or ceramic oscillator, circuit constants will differ depending on the resonator, stray
capacitance in the interconnecting circuit, and other factors. Suitable constants should be
determined in consultation with the resonator manufacturer.
2. Make the connections between the OSC₁ and OSC₂ pins (X1 and X2 pins) and external
components as short as possible, and ensure that no other lines cross these lines (see layout
example in figure 25).
3. When 32.768 kHz crystal oscillation is not used, fix the X1 pin at V_CC and leave the X2 pin open.
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