8-Bit Microcontroller with OTP ROM Specification Sheet

EM78P447N
8-Bit Microcontroller with OTP ROM
Product Specification (V1.1) 03.30.2005
• 23
(This specification is subject to change without further notice)
INT
ENI/DISI
IOD
RFWR
IOCFRD
IOCFWR
IRQn
IRQm
RFRD
IOCF
/RESET
/IRQn
VCC
RF
CLK
CLK
Q
Q
D
P
R
L
C
_
P
R
L
C
Q
Q
_
D
Fig. 9 Interrupt Input Circuit
4.7 Oscillator
4.7.1 Oscillator Modes
The EM78P447N can operate in three different oscillator modes, i.e., high XTAL (HXT)
oscillator mode, low XTAL (LXT) oscillator mode, and External RC oscillator mode
(ERC) oscillator mode. User can select one of them by programming MS, HLF and
HLP in the Code Option Register. Table 10 depicts how these three modes are
defined.
The maximum limit for operational frequencies of crystal/resonator under different
VDDs is listed in Table 10.
Table 10 Oscillator Modes Defined by MS and HLP
Mode MS HLF HLP
ERC(External RC oscillator mode) 0
*X *X
HXT(High XTAL oscillator mode) 1 1
*X
LXT(Low XTAL oscillator mode) 1 0 0
NOTE
1. X, Don’t care
2. The transient point of system frequency between HXT and LXY is around 400 KHz.