EM78P341N/342N/343N
8-Bit Microprocessor with OTP ROM
6.11 Oscillator
6.11.1 Oscillator Modes
The EM78P341N/342N/343N can be operated in six different oscillator modes, such as
High Crystal oscillator mode 1 (HXT1), High Crystal oscillator mode 2 (HXT2), Low
Crystal oscillator mode 1 (LXT1), Low Crystal oscillator mode 2 (LXT2), External RC
oscillator mode (ERC), and RC oscillator mode with Internal RC oscillator mode (IRC).
You can select one of them by programming the OSC2, OCS1, and OSC0 in the CODE
Option register.
The Oscillator modes defined by OSC2, OCS1, and OSC0 are described below.
Oscillator Modes
OSC2
OSC1
OSC0
ERC1 (External RC oscillator mode); P70/OSCO acts as P70
ERC1 (External RC oscillator mode); P70/OSCO acts as OSCO
IRC2 (Internal RC oscillator mode); P70/OSCO acts as P70
0
0
0
0
0
1
0
1
0
IRC2 (Internal RC oscillator mode); P70/OSCO acts as OSCO
LXT13 (Frequency range of XT mode is 1MHz ~ 100kHz)
HXT13 (Frequency range of XT mode is 20MHz ~ 6MHz)
LXT23 (Frequency range of XT mode is 32kHz)
0
1
1
1
1
1
0
0
1
1
1
0
1
0
1
HXT23 (Frequency range of XT mode is 6MHz ~ 1MHz) (default)
1 In ERC mode, OSCI is used as oscillator pin. OSCO/P50 is defined by code option Word 0 Bit 6 ~ Bit 4.
2 In IRC mode, P55 is normal I/O pin. OSCO/P70 is defined by code option Word 0 Bit 6 ~ Bit 4.
3 In LXT1, LXT2, HXT1 and HXT2 modes; OSCI and OSCO are used as oscillator pins. These pins cannot
and should not be defined as normal I/O pins.
The maximum operating frequency limit of crystal/resonator at different VDDs, are as
follows:
Conditions
VDD
1.7
Max. Freq. (MHz)
4
Two clocks
3.0
16
20
4.0
6.11.2 Crystal Oscillator/Ceramic Resonators (Crystal)
The EM78P341N/342N/343N can be driven by an external clock signal through the
OSCI pin as illustrated below.
OSCI
OSCO
Fig. 6-17 External Clock Input Circuit
Product Specification (V1.0) 12.01.2006
(This specification is subject to change without further notice)
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ELAN [ ELAN MICROELECTRONICS CORP ]
