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Full Swing Crystal Oscillator
Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be configured for use
as an On-chip Oscillator, as shown in Figure 9-2 on page 28. Either a quartz crystal or a ceramic resonator may be
used.
This Crystal Oscillator is a full swing oscillator, with rail-to-rail swing on the XTAL2 output. This is useful for driving
other clock inputs and in noisy environments. The current consumption is higher than the ”Low Power Crystal
Oscillator” on page 28. Note that the Full Swing Crystal Oscillator will only operate for VCC = 2.7 - 5.5 volts.
Low Power Crystal Oscillator
Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be configured for use
as an On-chip Oscillator, as shown in Figure 9-2 on page 28. Either a quartz crystal or a ceramic resonator may be
used.
This Crystal Oscillator is a low power oscillator, with reduced voltage swing on the XTAL2 output. It gives the lowest
power consumption, but is not capable of driving other clock inputs, and may be more susceptible to noise in
noisy environments.
上文摘自Atmel-8271-8-bit-AVR-Microcontroller-ATmega48A-48PA-88A-88PA-168A-168PA-328-328P_datasheet.pdf P28-P29,
简而言之:
全幅晶振可以使用石英或陶瓷振子,XTAL2输出是轨到轨的,这对驱动其它时钟输入端和在噪声大的环境中是有用的。这种
状态下消耗的电流要高于低功耗晶振。注意全幅晶振只能工作于2.7V-5.5V电源下。
低功耗晶振是减少了XTAL2输出的电压摆幅,这减少了电源的消耗,但是不适于驱动其它时钟输入端,在噪声大的环境中易受影响。
实际上这两种方式主要是设置MCU内部的振荡电路,对晶振来说没有区别,主要是看是否需要输出时钟信号、降低电流消耗和环境噪声大小的影响。
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