Fig. 9 Interrupt Input Circuit
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
7 depicts how these three modes are defined.
The maximum limit for operational frequencies of crystal/resonator under different VDDs is listed in
Table 7 Oscillator Modes Defined by MS and HLP
ERC(External RC oscillator mode)
HXT(High XTAL oscillator mode)
LXT(Low XTAL oscillator mode)
1. X, Don’t care
2. The transient point of system frequency between HXT and LXY is around 400 KHz.
This specification is subject to change without prior notice.