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S912XEG128J2MAA Datasheet, PDF (1224/1324 Pages) Freescale Semiconductor, Inc – Microcontrollers
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Appendix A Electrical Characteristics
A.3 NVM, Flash and Emulated EEPROM
A.3.1 Timing Parameters
The time base for all NVM program or erase operations is derived from the oscillator. A minimum
oscillator frequency fNVMOSC is required for performing program or erase operations. The NVM modules
do not have any means to monitor the frequency and will not prevent program or erase operation at
frequencies above or below the specified minimum. When attempting to program or erase the NVM
modules at a lower frequency, a full program or erase transition is not assured.
The program and erase operations are timed using a clock derived from the oscillator using the FCLKDIV
register. The frequency of this clock must be set within the limits specified as fNVMOP.
The minimum program and erase times shown in Table A-19 are calculated for maximum fNVMOP and
maximum fNVMBUS unless otherwise shown. The maximum times are calculated for minimum fNVMOP
A.3.1.1 Erase Verify All Blocks (Blank Check) (FCMD=0x01)
The time it takes to perform a blank check is dependant on the location of the first non-blank word starting
at relative address zero. It takes one bus cycle per phrase to verify plus a setup of the command. Assuming
that no non blank location is found, then the erase verify all blocks is given by.
tcheck = 33500 ⋅ f--N----V---M-1---B---U----S-
A.3.1.2 Erase Verify Block (Blank Check) (FCMD=0x02)
The time it takes to perform a blank check is dependant on the location of the first non-blank word starting
at relative address zero. It takes one bus cycle per phrase to verify plus a setup of the command. Assuming
that no non blank location is found, then the erase verify time for a single 256K NVM array is given by
tcheck = 33500 ⋅ f--N----V---M-1---B---U----S-
For a 128K NVM or D-Flash array the erase verify time is given by
tcheck = 17200 ⋅ f--N----V---M-1---B---U----S-
A.3.1.3 Erase Verify P-Flash Section (FCMD=0x03)
The maximum time depends on the number of phrases being verified (NVP)
tcheck = (752 + NVP) ⋅ -f-N----V---M-1---B---U----S-
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MC9S12XE-Family Reference Manual Rev. 1.25
Freescale Semiconductor
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