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EM78P468N/EM78P468L
8-Bit Microcontroller
32 •
Product Specification (V1.5) 02.15.2007
(This specification is subject to change without further notice)
6.6.4 RC Oscillator Mode with Internal Capacitor
If both precision and cost are taken into consideration, this LSI also offers a special
oscillation mode, which has an on-chip internal capacitor and an external resistor
connected to VDD. The internal capacitor functions as temperature compensator. In
order to obtain more accurate frequency, a precise resistor is recommended.
EM78P468N
R-OSCI or Xin
Rext
VDD
Fig. 6-9 Circuit for Internal C Oscillator Mode
Table 6 RC Oscillator Frequencies
Pin Rext
Average Fosc 5V, 25°C Average Fosc 3V, 25°C
51k 2.2221 MHz 2.1972 MHz
100k 1.1345 MHz 1.1203 MHz
R-OSCI
300k 381.36kHz 374.77kHz
Xin 2.2M 32.768kHz 32.768kHz
Note: Measured from QFP packages with frequency drift of about ±30%.
Values are provided for design reference only.
6.7 Power-on Considerations
Any microcontroller (as with this LSI) is not warranted to start operating properly before
the power supply stabilizes in a steady state. This LSI has an on-chip Power-on Reset
(POR) with detection level range as shown on the table below. The circuitry eliminates
the extra external reset circuit but will work well only if the VDD rises quickly enough (50
ms or less). However, under critical applications, extra devices are still required to
assist in solving power-on problems.
Power-on voltage detector provided
IC Voltage Range
EM78P468N 1.9V to 2.1V
EM78P468L 1.6V to 1.8V