MMC2107 - Freescale Semiconductor

Non-Volatile Memory FLASH (CMFR)
Freescale Semiconductor, Inc.
Table 9-10 Erase Interlock State Descriptions (Continued)
State
Mode
Next
State
Transition Requirement
nc...
Freescale Semiconductor, I
S3
S4
S5
High voltage write enable: Erase margin
reads occur. CMFR accepts erase hardware
interlock write. Normal register accesses
(except CMFRMCR). CMFRMCR write
causes NVM fuses to be cleared during the
high-voltage pulse. If CMFRMCR was
written, a CMFRMCR read returns the NVM
fuses value. CMFRCTL write can change
EHV. When HVS goes high, NVR and
PAWS are locked.
Erase operation: High voltage applied to
array blocks to erase bitcells. Pulse-width
timer active if SCLKR[2:0] ≠ 0; HVS can be
polled to time the erase pulse. During erase,
array cannot be accessed (bus error).
Normal register accesses. CMFRCTL write
can change only EHV.
Erase margin read operation: Reads
determine if bits in selected blocks need
modification by the erase operation. Erased
bit reads as 1. All words in erased blocks
must be read to determine if erase is
complete.
9.8.5.2 Erase Margin Reads
S1
T6 Write SES = 0 or a master reset
S4 T4 Write EHV = 1
S1
T7 Master reset
S5 T5 EHV = 0 and HVS = 0
S4 T8 Write EHV = 1
S1
T9 Write SES = 0 or a master reset
The CMFR provides an erase margin read with electrical margin for the
erase state. Erase margin reads provide sufficient margin to assure
specified data retention. The erase margin read is enabled when
SES = 1 and the erase write has occurred. The erase margin read and
subsequent on-page erase verify reads return a 0 for any bit that has not
completely erased. Bits that have completed erasing read as a 1s. To
increase the access time of the erase margin read, the off-page access
time is 17 clocks instead of the usual 2-clock off-page read access time.
The erase margin read occurs while doing an off-page read. All locations
within the block(s) that are being erased must read as a 1 to determine
that no more erase pulses are required.
Technical Data MMC2107 – Rev. 2.0
218 Non-Volatile Memory FLASH (CMFR) MOTOROLA
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