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
RF
XTAL
C
1
OSCO
RS
OSCI
OSCO
Open
C
2
Clock from
external system
(a) Crystal Operation (or Ceramic Resonator)
3.6.2 RC Oscillator Mode
R
OSCI
C
0
÷
4
(b) External Clock Input Operation
CTM8B54E/55E/56E/57E
internal
clock
OSCO
3.7 CONFIGURATION WORD
Bit 3
Bit2
Bit1
Bit0
Code Protect WDT Enable Oscillator Type Oscillator Type
1
x
x
x
0
x
x
x
x
1
x
x
x
0
x
x
1
1
x
x
0
1
x
x
1
0
x
x
0
0
x
x
Function
EPROM unprotected
EPROM protected
Watchdog Timer enable
Watchdog Timer disable
RC
HFXTAL
XTAL
LFXTAL
Remark
Default
Default
Default
* 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
Email: server@ceramate.com.tw
Tel:886-3-3529445
Http: www.ceramate.com.tw
Page 11 of
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Rev 1.1 Dec 26,2001
Fax:886-3-3521052
CERAMATE [ CERAMATE TECHNICAL ]
