PSD834F2-15M STMicroelectronics, PSD834F2-15M Datasheet - Page 21

• Manufacturer Part Number: PSD834F2-15M
• Manufacturer: STMicroelectronics

Specifications of PSD834F2-15M

• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Package Type: PQFP
• Mounting: Surface Mount
• Pin Count: 52
• Lead Free Status / RoHS Status: Compliant

Erasing Flash Memory
Flash Bulk Erase. The Flash Bulk Erase instruc-
tion uses six WRITE operations followed by a
READ operation of the status register, as de-
scribed in Table 7. If any byte of the Bulk Erase in-
struction is wrong, the Bulk Erase instruction
aborts and the device is reset to the Read Flash
memory status.
During a Bulk Erase, the memory status may be
checked by reading the Error Flag (DQ5) Bit, the
Toggle Flag (DQ6) Bit, and the Data Polling Flag
(DQ7) Bit, as detailed in the section entitled “Pro-
gramming Flash Memory”, on page 19. The Error
Flag (DQ5) Bit returns a '1' if there has been an
Erase Failure (maximum number of Erase cycles
have been executed).
It is not necessary to program the memory with
00h because the PSD automatically does this be-
fore erasing to 0FFh.
During execution of the Bulk Erase instruction, the
Flash memory does not accept any instructions.
Flash Sector Erase. The Sector Erase instruc-
tion uses six WRITE operations, as described in
Table 7. Additional Flash Sector Erase codes and
Flash memory sector addresses can be written
subsequently to erase other Flash memory sec-
tors in parallel, without further coded cycles, if the
additional bytes are transmitted in a shorter time
than the time-out period of about 100µs. The input
of a new Sector Erase code restarts the time-out
period.
The status of the internal timer can be monitored
through the level of the Erase Time-out Flag (DQ3)
Bit. If the Erase Time-out Flag (DQ3) Bit is '0,' the
Sector Erase instruction has been received and
the time-out period is counting. If the Erase Time-
out Flag (DQ3) Bit is '1,' the time-out period has
expired and the PSD is busy erasing the Flash
memory sector(s). Before and during Erase time-
out, any instruction other than Suspend Sector
Erase and Resume Sector Erase instructions
abort the cycle that is currently in progress, and re-
set the device to READ Mode. It is not necessary
to program the Flash memory sector with 00h as
the PSD does this automatically before erasing
(byte=FFh).
During a Sector Erase, the memory status may be
checked by reading the Error Flag (DQ5) Bit, the
Toggle Flag (DQ6) Bit, and the Data Polling Flag
(DQ7) Bit, as detailed in the section entitled “Pro-
gramming Flash Memory”, on page 19.
During execution of the Erase cycle, the Flash
memory accepts only Reset and Suspend Sector
Erase instructions. Erasure of one Flash memory
sector may be suspended, in order to read data
from another Flash memory sector, and then re-
sumed.
Suspend Sector Erase. When a Sector Erase
cycle is in progress, the Suspend Sector Erase in-
struction can be used to suspend the cycle by writ-
ing 0B0h to any address when an appropriate
Sector Select (FS0-FS7 or CSBOOT0-CSBOOT3)
is High. (See Table 7). This allows reading of data
from another Flash memory sector after the Erase
cycle has been suspended. Suspend Sector
Erase is accepted only during an Erase cycle and
defaults to READ Mode. A Suspend Sector Erase
instruction executed during an Erase time-out pe-
riod, in addition to suspending the Erase cycle, ter-
minates the time out period.
The Toggle Flag (DQ6) Bit stops toggling when the
PSD internal logic is suspended. The status of this
bit must be monitored at an address within the
Flash memory sector being erased. The Toggle
Flag (DQ6) Bit stops toggling between 0.1µs and
15µs after the Suspend Sector Erase instruction
has been executed. The PSD is then automatically
set to READ Mode.
If an Suspend Sector Erase instruction was exe-
cuted, the following rules apply:
– Attempting to read from a Flash memory sector
– Reading from a Flash sector that was not being
– The Flash memory cannot be programmed, and
– If a Reset Flash instruction is received, data in
Resume Sector Erase. If a Suspend Sector
Erase instruction was previously executed, the
erase cycle may be resumed with this instruction.
The Resume Sector Erase instruction consists of
writing 030h to any address while an appropriate
Sector Select (FS0-FS7 or CSBOOT0-CSBOOT3)
is High. (See Table 7.)
that was being erased outputs invalid data.
erased is valid.
only responds to Resume Sector Erase and
Reset Flash instructions (READ is an operation
and is allowed).
the Flash memory sector that was being erased
is invalid.
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