MC68HC05B6_13 Datasheet, PDF (40/302 Pages) Freescale Semiconductor, Inc – Microcontrollers

2.5.8.3 External clock
2
An external clock should be applied to the OSC1 input, with the OSC2 pin left unconnected, as
shown in Figure 2-5(c). 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
OSC1
OSC2
R_P
C_OSC1
C_OSC2
(a) Crystal/ceramic resonator
oscillator connections
C₀
(b) Crystal equivalent circuit
MCU
OSC1
OSC2
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
MΩ
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 2-5 Oscillator connections
Freescale
2-12
MODES OF OPERATION AND PIN DESCRIPTIONS
MC68HC05B6
Rev. 4.1