CP80S54 Datasheet, PDF (23/47 Pages) List of Unclassifed Manufacturers – EPROM/ROM-Based 8-Bit Microcontroller Series

CP80S54/56
2.8 Oscillator Configurations
CP80S54/S56 can be operated in four different oscillator modes. Users can program three configuration bits
(Fosc<2:0>) to select the appropriate modes:
‧ ERC: External Resistor/Capacitor Oscillator
‧ HF: High Frequency Crystal/Resonator Oscillator
‧ XT: Crystal/Resonator Oscillator
‧ LF: Low Frequency Crystal Oscillator
‧ IRC: Internal Resistor/Capacitor Oscillator
‧ ERIC: External Resistor/Internal Capacitor Oscillator
In LF, XT, or HF modes, a crystal or ceramic resonator in connected to the OSCI and OSCO pins to establish
oscillation. When in LF, XT, or HF modes, the devices can have an external clock source drive the OSCI pin.
The ERC device option offers additional cost savings for timing insensitive applications. The RC oscillator
frequency is a function of the resistor (Rext) and capacitor (Cext), the operating temperature, and the process
parameter.
The IRC/ERIC device option offers largest cost savings for timing insensitive applications. These devices offer 4
different internal RC oscillator frequency, 8MHz, 4MHz, 1MHz, and 455KHz, which is selected by two configuration
bits (RCM<1:0>). Or user can change the oscillator frequency with external resistor. The ERIC oscillator frequency
is a function of the resistor (Rext), the operating temperature, and the process parameter.
FIGURE 2.6: HF, XT, or LF Oscillator Modes (Crystal Operation or Ceramic Resonator)
C1
OSCI
CP80S54/S56
X’TAL
RF
C2
RS _OSCO
SLEEP
Internal
Circuit
FIGURE 2.7: HF, XT, or LF Oscillator Modes (External Clock Input Operation)
Clock from
External System
OSCI
CP80S54/S56
OSCO
Open
Rev0.1 Nov 30, 2005
P.23/CP80S54/S56