CTM8B54E/55E/56E/57E
EPROM-Based 8-Bit CMOS Microcontroller
3.6 OSCILLATOR CONFIGURATION
This device supports four oscillator modes. Users can program two configuration bits to select the appropriate
mode. These oscillator modes offered as:
• RC: Low-cost crystal
• XTAL: Standard crystal oscillator
• HFXTAL: High frequency crystal oscillator
• LFXTAL: Low frequency crystal oscillator
3.6.1 XTAL, HFXTAL or LFXTAL modes
CTM8B54E/55E/56E/57E
Internal
Circuit
CTM8B54E/55E/56E/57E
SLEEP
OSCI
OSCO
Open
OSCI
OSCO
RS
RF
XTAL
Clock from
external system
C2
C1
(b) External Clock Input Operation
(a) Crystal Operation (or Ceramic Resonator)
3.6.2 RC Oscillator Mode
R
CTM8B54E/55E/56E/57E
internal
clock
OSCI
C
0 ¸ 4
OSCO
3.7 CONFIGURATION WORD
Bit 3
Bit2
Bit1
Bit0
Function
Remark
Default
Code Protect WDT Enable Oscillator Type Oscillator Type
1
0
x
x
x
x
x
x
x
x
1
0
x
x
x
x
x
x
x
x
1
1
0
0
x
x
x
x
1
0
1
0
EPROM unprotected
EPROM protected
Watchdog Timer enable
Watchdog Timer disable
RC
Default
Default
HFXTAL
XTAL
LFXTAL
* All specs and applications shown above subject to change without prior notice.
1F-5 NO.66 SEC.2 NAN-KAN RD ., LUCHU , TAOYUAN, TAIWAN, R.O.C
Tel:886-3-3529445
Fax:886-3-3521052
Email: server@ceramate.com.tw
Http: www.ceramate.com.tw
Rev 1.1 Dec 26,2001
Page 11 of 23
CERAMATE [ CERAMATE TECHNICAL ]
