MC68HC05B4 Datasheet, PDF (186/298 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

D.3
External clock
When using an external clock the OSC1 and OSC2 pins should be driven in antiphase, as shown
in Figure D-2. The t_OXOV or t_ILCH specifications (see Section 11.4) do not apply when using an
external clock input. The equivalent specification of the external clock source should be used in
lieu of t_OXOV or t_ILCH.
OSC1
L
C₁
R_S
OSC2
MCU
C₀
OSC1
OSC2
C_OSC1
C_OSC2
(a) Crystal/ceramic resonator
oscillator connections
(b) Crystal equivalent circuit
MCU
OSC1
OSC2
14
External
NC
clock
(c) External clock source connections
Crystal
2MHz 4MHz Unit
R_S(max) 400
75
Ω
C₀
5
7
pF
C₁
8
12
ƒF
C_OSC1 15 – 40 15 – 30 pF
C_OSC2 15 – 30 15 – 25 pF
R_P
10
10 M Ω
Q
30 000 40 000 —
Ceramic resonator
2 – 4MHz Unit
R_S(typ)
10
Ω
C₀
40
pF
C₁
4.3
pF
C_OSC1
30
pF
C_OSC2
30
pF
R_P
1 – 10 MΩ
Q
1250
—
(d) Typical crystal and ceramic resonator parameters
Figure D-2 Oscillator connections
MOTOROLA
D-4
MC68HC05B16
TPG
MC68HC05B6
Rev. 4