HD404669 Datasheet, PDF (44/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
Crystal oscillator
(X1, X2)
Circuit Configuration
C₁
X1
Crystal
oscillator
C₂
GND
X2
L C_S R_S
Circuit Constants
Crystal oscillator: 32.768 kHz: MX38T
(Nippon Denpa)
C₁ = C₂ = 20 pF ± 20%
R_S=14 kΩ
C₀=1.5 pF
X1
X2
C₀
Notes: 1. Circuit constants differ by the different types of crystal oscillators, ceramic oscillators, and with the
stray capacitance of the board, so consult the manufacturer of the oscillator to determine the
circuit parameters.
2. The wiring between the OSC₁, OSC₂ (X1 and X2 pins), and the other elements should be as short
as possible, and must not cross other wiring. Refer to figure 26.
3. If not using a 32.768-kHz crystal oscillator, fix the X1 pin to V_CC and leave the X2 pin open.
GND
X2
X1
RESET
OSC₂
OSC₁
TEST
GND
Figure 26 Typical Layouts of Crystal and Ceramic Oscillator
44