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6134AS–CASIC–08-Mar-05

ATC13 Summary

6.

Oscillator Cell Library, Osc33lib

The Atmel Oscillator Library provides stable clock sources. It comprises five oscillators.

The Atmel two-pad oscillators are designed with the Pierce three-point oscillator

structure.

For the 32.768 kHz oscillator, the load capacitance must be between 6 pF and 12.5 pF.

For high-frequency oscillators, the load capacitance must be between 15 pF and 20 pF.

External capacitors must be added in order to obtain the correct load capacitance.

Clock output is high at off state (onosc = 0). The oscillators provide a bypass mode

(onosc = 0), clock = not (xin). Table 6-1 gives the available Osc33lib cells and their

major characteristics.

Table 6-1.

Oscillator Cells

Cell Name

Description

OSC33f33K

32.786 kHz crystal

OSC33f9M

4 - 9 MHz crystal oscillator

OSC33f16M

8 - 16 MHz crystal oscillator

OSC33f27M

10 - 27 MHz crystal oscillator

OSC33KLP

32.786 kHz uPower crystal oscillator (available in 1.2V)