em78p5842 ELAN Microelectronics Corp, em78p5842 Datasheet - Page 34

• Manufacturer Part Number: em78p5842
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

VII.11 Oscillator
The EM785840 can be operated in two different oscillator modes, each of them are crystal mode and RC mode.
Users can select one of them by setting code option. The descript of these two oscillator mode are as below:
(1) Crystal mode:
eFT5840 can be run in four active mode include normal mode, green mode and sleep mode. The advantages of this
mode are low power consumption (in green mode) and with more precise main CLK. Next figure show the
application circuit of crystal mode. Pin XIN and pin XOUT can be connected with a crystal directly to generate
oscillation. By clear code option”P70S” to 0, PORT70 can switch to general IO (disable PLL function and
EM785840 can not active on normal mode); /RESET pin can switch to PORT71 if clear “P71S” to 0.
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* This specification is subject to change without notice.
For crystal mode operation, one crystal and tow capacitances is needed for external circuit. In this mode,
operation
RESET
Fig 14: The relative of Crystal mode’s normal, green and sleep mode
Reset release
Reset
Reset
Fig 13: Application circuit of Crystal mode
e F H 5840
X O U T
Reset
X I N
IRC1 : ON
32K : un-active
PLL : turn off
IRC1 : ON
32K : oscillating
PLL : turn off
(CPU stop)
Green
Mode
Mode
Sleep
32
RA page0 bit7 = 0
& run"SLEP"
PLLEN bit = 1
PLLEN bit = 0
EM785840/5841/5842
8-bit Micro-controller
2004/11/10 V1.2
IRC1 : ON
32K : oscillating
PLL : turn on
Normal
Mode