Electronic – Looking for AVR MCU with internal PLL clock source with more than 8 pins

atmegaattinyavrmicrocontrollerusb device

The 8-pin AtTiny x5 MCU (ie. AtTiny25, AtTiny45 and AtTiny85)
can be set to use it's internal clock source
to something as high as 16Mhz without any external components
by setting PLLCLK which would enable the internal PLL for high frequency clock generation (no crystal or capacitor or what ever is needed).

This feature can be used to implement a simple and cheap USB device
as in V-USB with ATtiny45 / ATtiny85 without a crystal

Is there any AVR (AtMega or AtTiny) with more than 8 pins having this feature (referring to PLL)?

Best Answer

There are several AVRs with more than 8 pins, that incorporate the PLL clock multiplier based on the internal RC oscillator. Unfortunately, this is not one of the parameters that can be searched for on the Atmel site.

There is, however, a work-around:

Search through all the include files (*.h) in your AVRGCC installation folder for the string PLLCSR. The headers for the AVR parts which do have the PLL will show up. After that, you would still need to go through the datasheets of that subset to check for number of pins, and to check for a line like this:

On chip PLL for fast PWM (32MHz, 48MHz, 64MHz) and CPU (12MHz, 16MHz); PLL source RC & XTAL

On a quick scan, I found the AT90PWM81/161 to meet the requirements, there are several others too.

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