Description
No, the internal oscillator for the MAX II flash memory block is not enabled at all times. During the In-System Programming (ISP) mode, the internal oscillator for the program /erase operation is only activated when the flash memory block is being programmed or erased, while the internal oscillator for read operation is activated whenever the flash memory block is reading data out. The frequency range for the program/erase oscillator is around 50MHz, while the frequency range for the read oscillator is around 25 to 35Mhz.
When the MAX II device is running in user mode, the internal oscillator for the User Flash Memory (UFM) block is enabled when the ERASE , PROGRAM and READ operation is executed. The frequency range for the internal oscillator is 13Mhz to 22Mhz. You can enable the UFM internal oscillator by asserting the OSC_ENA signal and output the oscillator signal through the OSC port of the UFM block to the logic element (LE). The output frequency of the OSC port is one-fourth that of the oscillator frequency. As a result, the frequency range of the OSC port is 3.3 to 5.5 MHz.