em78p468l ELAN Microelectronics Corp, em78p468l Datasheet - Page 38

• Manufacturer Part Number: em78p468l
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

EM78P468N/EM78P468L
8-Bit Microcontroller
32 •
6.7 Power-on Considerations
6.6.4
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.
Table 6 RC Oscillator Frequencies
Note: Measured from QFP packages with frequency drift of about ±30%.
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
R-OSCI
Pin
Xin
RC Oscillator Mode with Internal Capacitor
Values are provided for design reference only.
EM78P468N
EM78P468L
Rext
100k
300k
2.2M
51k
IC
Fig. 6-9 Circuit for Internal C Oscillator Mode
R-OSCI or Xin
EM78P468N
Average Fosc 5V, 25°C
2.2221 MHz
1.1345 MHz
381.36kHz
32.768kHz
(This specification is subject to change without further notice)
Voltage Range
Product Specification (V1.5) 02.15.2007
1.9V to 2.1V
1.6V to 1.8V
VDD
Rext
Average Fosc 3V, 25°C
2.1972 MHz
1.1203 MHz
374.77kHz
32.768kHz