EM78156EAS EMC [ELAN Microelectronics Corp], EM78156EAS Datasheet - Page 28

• Manufacturer Part Number: EM78156EAS
• Description: 8-Bit Microcontroller with MASK ROM
• Manufacturer: EMC [ELAN Microelectronics Corp]

EM78156E
8-Bit Microcontroller with MASK ROM
24 •
The smaller the Rext in the RC oscillator, the faster its frequency will be. On the
contrary, for very low Rext values, for instance, 1 KΩ, the oscillator becomes unstable
because the NMOS cannot discharge the current of the capacitance correctly.
Based on the above reasons, it must be kept in mind that all of the supply voltage, the
operation temperature, the components of the RC oscillator, the package types, the
way the PCB is layout, will affect the system frequency.
Table 11 RC Oscillator Frequencies
100 pF
300 pF
20 pF
Cext
Fig. 13 Circuit for External RC Oscillator Mode
EM78156E
OSCI
Rext
100k
100k
100k
3.3k
5.1k
3.3k
5.1k
3.3k
5.1k
1. Measured on DIP packages.
2. For design reference only.
3. The frequency drift is about
10k
10k
10k
(This specification is subject to change without further notice)
NOTE
Average Fosc
Cext
Vcc
Product Specification (V1.3) 07.29.2004
Rext
3.92 MHz
2.67 MHz
1.39 MHz
1.39 MHz
149 KHz
940 KHz
480 KHz
595 KHz
400 KHz
200 KHz
5V,25°C
52 KHz
21 KHz
±
30%
Average Fosc
3.65 MHz
2.60 MHz
1.40 MHz
1.33 MHz
156 KHz
920 KHz
475 KHz
560 KHz
390 KHz
200 KHz
3V,25°C
50 KHz
20 KHz