EM78P468NBQSSLASHNBQJ datasheet(38/82 Pages) EMC

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EM78P468N/L

8-Bit Microcontroller

•

Product Specification (V1.6) 12.31.2007

(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

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

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

Voltage Range

EM78P468N

1.9V to 2.1V

EM78P468L

1.6V to 1.8V

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