EM78P451SWM datasheet(42/54 Pages) EMC

42 / 54 page

EM78P451S

8-Bit Microcontroller with OTP ROM

•

Product Specification (V1.0) 06.01.2004

(This specification is subject to change without further notice)

CLK

/IRQn

R3F

RESET

IOCF

RFWR

IOCFRD

IOCFWR

RFRD

IRQn

IRQm

IOD

ENI/DISI

interrupt

Fig. 17 Interrupt Input Circuit

4.9 Oscillator

4.9.1 Oscillator Modes

The EM78P451S can operate in four different oscillator modes. There are high XTAL

(HXT) oscillator mode, low XTAL (LXT) oscillator mode, External RC oscillator mode

(ERC), and Internal C、External R oscillator modes. User can select one of them by

programming MS, RCT, HLF and HLP in the Code Option Register. Table 9 depicts

how these three modes are defined.

Table 10 Oscillator Modes by MS, IRC, RCT.

Mode

RCT

HLF

HLP

High XTAL Oscillator

Low XTAL Oscillator

External RC Oscillator

External R and Internal C Oscillator

<Note> X: Don’t care

4.9.2 Crystal Oscillator/Ceramic Resonators (XTAL)

EM78P451S can be driven by an external clock signal through the OSCI pin as shown

in Fig 18 below. In the most applications, pin OSCI and pin OSCO is connected with a

crystal or ceramic resonator to generate oscillation. Fig 19 depicts such circuit. Table

10 provides the recommended values of C1 and C2. Since each resonator has its own

attribute, user should refer to its specification for appropriate values of C1 and C2. RS,

a serial resistor may be necessary for AT strip cut crystal or low frequency mode.

EM78P451SWM Datasheet(PDF) 42 Page - ELAN Microelectronics Corp

EM78P451SWM Datasheet(HTML) 42 Page - ELAN Microelectronics Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Datasheet Download

Link URL