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EM78P259N/260N
8-Bit Microprocessor with OTP ROM
64 •
Product Specification (V1.2) 05.18.2007
(This specification is subject to change without further notice)
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 way the PCB is layout, have certain effect on the system frequency.
The RC Oscillator frequencies:
Cext Rext Average Fosc 5V, 25°C Average Fosc 3V, 25°C
3.3k 3.5 MHz 3.2 MHz
5.1k 2.5 MHz 2.3 MHz
10k 1.30 MHz 1.25 MHz
20 pF
100k 140kHz 140kHz
3.3k 1.27 MHz 1.21 MHz
5.1k 850kHz 820kHz
10k 450kHz 450kHz
100 pF
100k 48kHz 50kHz
3.3k 560kHz 540kHz
5.1k 370kHz 360kHz
10k 196kHz 192kHz
300 pF
100k 20kHz 20kHz
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
EM78P259N/260N 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 EM78P259N/260N internal RC drift with voltage, temperature, and
process variation.
Internal RC Drift Rate (Ta=25
°
C, VDD=5V±5%, VSS=0V)
Drift Rate
Internal
RC Frequency
Temperature
(-40
°
C ~ +85
°
C)
Voltage
(2.3V~5.5V)
Process Total
4MHz ±10% ±5% ±4% ±19%
8MHz ±10% ±6% ±4% ±20%
1MHz ±10% ±5% ±4% ±19%
455MHz ±10% ±5% ±4% ±19%
Note: These are theoretical values provided for reference only. Actual values may vary depending on the
actual process.