Holtek BS66F340C Manual page 73

BS66F340C/BS66F350C/BS66F360C
Touch A/D Flash MCU
High Speed
HXTEN
HIRCEN
LXTEN
External Crystal/Resonator Oscillator – HXT
The External Crystal/Resonator Oscillator is one of the high frequency oscillators. For most crystal
oscillator configurations, the simple connection of a crystal across OSC1 and OSC2 will create the
necessary phase shift and feedback for oscillation, without requiring external capacitors. However,
for some crystal types and frequencies, to ensure oscillation, it may be necessary to add two small
value capacitors, C1 and C2. Using a ceramic resonator will usually require two small value
capacitors, C1 and C2, to be connected as shown for oscillation to occur. The values of C1 and C2
should be selected in consultation with the crystal or resonator manufacturer's specification.
For oscillator stability and to minimise the effects of noise and crosstalk, it is important to ensure
that the crystal and any associated resistors and capacitors along with interconnecting lines are all
located as close to the MCU as possible.
Rev. 1.11
Oscillators
HXT
IDLE0
HIRC
SLEEP
FHS
Low Speed
Oscillators
LXT
IDLE2
LIRC
SLEEP
FSS
System Clock Configurations
C1
C2
Note: 1. R is normally not required. C1 and C2 are required.
P
2. Although not shown OSC1/OSC2 pins have a parasitic
capacitance of around 7pF.
Crystal/Resonator Oscillator – HXT
HXT Oscillator C1 and C2 Values
Crystal Frequency
16MHz
12MHz
8MHz
4MHz
1MHz
Note: C1 and C2 values are for guidance only.
HXT Crystal Recommended Capacitor Values
73
f
H
f /2
H
f /4
H
f /8
H
Prescaler
f /16
H
f /32
H
f /64
H
f
SUB
OSC1
R
P
OSC2
C1 C2
0pF 0pF
0pF 0pF
0pF 0pF
0pF 0pF
100pF 100pF
November 09, 2023
f
SYS
CKS2~CKS0
f
SUB
f
LIRC