found this in a data sheet
31.3 ATmega644P
| Speed (MHz) (3) | Power Supply | Ordering code | Package (1) | Operational range |
|---|---|---|---|---|
| 10 | 1.8 - 5.5V | ATmega644PV-10AU (2) | 44A | Industrial (-40oC to 85oC) |
| 10 | 1.8 - 5.5V | ATmega644PV-10PU (2) | 40P6 | Industrial (-40oC to 85oC) |
| 10 | 1.8 - 5.5V | ATmega644PV-10MU (2) | 44M1 | Industrial (-40oC to 85oC) |
| 20 | 2.7 - 5.5V | ATmega644P-20AU (2) | 44A | Industrial (-40oC to 85oC) |
| 20 | 2.7 - 5.5V | ATmega644P-20PU (2) | 40P6 | Industrial (-40oC to 85oC) |
| 20 | 2.7 - 5.5V | ATmega644P-20MU (2) | 44M1 | Industrial (-40oC to 85oC) |
Notes: 1. This device can also be supplied in wafer form. Please contact your local Atmel sales office for detailed ordering information
and minimum quantities.
2. Pb-free packaging, complies to the European Directive for Restriction of Hazardous Substances (RoHS directive). Also
Halide free and fully Green.
3. For Speed vs. VCC see ”Speed Grades” on page 330.