There are several important considerations in designing an output stage that is up to the job. The average power dissipated determines how big the heatsink must be to keep output device junction temperatures down to safe levels. The peak power dissipated in the output devices must also be considered as the effects of this are not averaged by the heatsink mass. Audio waveforms have large low-frequency components, too slow for peak currents and powers to be allowed to exceed the DC limits on the data sheet. The peak collector current must be examined to make sure is within the limits for each device. These quantities determine the type and number of output devices.