Z8F012A View Datasheet(PDF) - Zilog

Part Name

Description

Manufacturer

Z8F012A

High-Performance 8-Bit Microcontrollers Z8 Encore! XP® F082A Series

Zilog 

Z8 Encore! XP® F082A Series

Product Specification

201

Oscillator Operation with an External RC Network

Figure 28 displays a recommended configuration for connection with an external resistor-

capacitor (RC) network.

VDD

R

XIN

C

Figure 28. Connecting the On-Chip Oscillator to an External RC Network

An external resistance value of 45 k is recommended for oscillator operation with an

external RC network. The minimum resistance value to ensure operation is 40 kThe

typical oscillator frequency can be estimated from the values of the resistor (R in k) and

capacitor (C in pF) elements using the following equation:

Oscillator Frequency (kHz)

=

----------------------1-----1---0--6----------------------

0.4  R  C + 4  C

Figure 29 displays the typical (3.3 V and 25°C) oscillator frequency as a function of the

capacitor (C, in pF) employed in the RC network assuming a 45 K external resistor. For

very small values of C, the parasitic capacitance of the oscillator XIN pin and the printed

circuit board must be included in the estimation of the oscillator frequency.

It is possible to operate the RC oscillator using only the parasitic capacitance of the pack-

age and printed circuit board. To minimize sensitivity to external parasitics, external

capacitance values in excess of 20 pF are recommended.

PS022827-1212

P R E L I M I N A R Y Oscillator Operation with an External RC

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