EM78P341N/342N/343N
8-Bit Microprocessor with OTP ROM
Based on the above reasons, it must be kept in mind that all supply voltage, the
operation temperature, the components of the RC oscillator, the package types, and
the PCB layout have certain effects on the system frequency.
The RC Oscillator frequencies:
Cext
Rext
3.3k
Average Fosc 5V, 25°C
Average Fosc 3V, 25°C
3.5 MHz
2.5 MHz
1.30 MHz
140 KHz
1.27 MHz
850kHz
450kHz
48kHz
3.2 MHz
2.3 MHz
1.25 MHz
140kHz
1.21 MHz
820kHz
450kHz
50kHz
5.1k
10k
20 pF
100k
3.3k
5.1k
10k
100 pF
300 pF
100k
3.3k
5.1k
10k
560kHz
370kHz
196kHz
20kHz
540kHz
360kHz
192kHz
20kHz
100k
Note: 1: Measured based on DIP packages.
2: The values are for design reference only.
3: The frequency drift is ± 30%
6.11.4 Internal RC Oscillator Mode
The EM78P341N/342N/343N offers a versatile internal RC mode with default
frequency value of 4MHz. Internal RC oscillator mode has other frequencies (1MHz,
8MHz, and 455kHz) that can be set by Code Option (Word 1), RCM1, and RCM0. The
Table below describes the EM78P341N/342N/343N internal RC drift with voltage,
temperature, and process variations.
Internal RC Drift Rate (Ta=25°C, VDD=5V±5%, VSS=0V)
Drift Rate
Internal
RC Frequency
Temperature
(-40°C ~+85°C)
Voltage
Process
Total
(2.3V~5.5V)
4MHz
16MHz
1MHz
±5%
±5%
±5%
±5%
±5%
±5%
±5%
±5%
±4%
±4%
±4%
±4%
±14%
±14%
±14%
±14%
455MHz
Theoretical values are for reference only. Actual values may vary depending on the actual
process.
72 •
Product Specification (V1.0) 12.01.2006
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
