PSD4235G2-90U STMicroelectronics, PSD4235G2-90U Datasheet - Page 47

• Manufacturer Part Number: PSD4235G2-90U
• Description: IC FLASH 4MBIT 90NS 80TQFP
• Manufacturer: STMicroelectronics

Specifications of PSD4235G2-90U

• Format - Memory: FLASH
• Memory Type: FLASH
• Memory Size: 4M (512K x 8)
• Speed: 90ns
• Interface: Parallel
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 80-TQFP, 80-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-1968

PSD4235G2
10
10.1
Erasing Flash memory
Flash Bulk Erase
The Flash Bulk Erase instruction uses six WRITE operations followed by a READ operation
of the status register, as described in
wrong, the Bulk Erase instruction aborts and the device is reset to the Read Memory mode.
During a Bulk Erase, the memory status may be checked by reading the Error Flag bit
(DQ5/DQ13), the Toggle Flag bit (DQ6/DQ14), and the Data Polling bit (DQ7/DQ15), as
detailed in
’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 before erasing to 0FFh.
During execution of the Bulk Erase instruction, the Flash memory does not accept any
instructions.
Flash Sector Erase
The Sector Erase instruction uses six WRITE operations, as described in
Additional Flash Sector Erase confirm commands and Flash memory sector addresses can
be written subsequently to erase other Flash memory sectors in parallel, without further
coded cycles, if the additional commands are transmitted in a shorter time than the timeout
period of about 100 µs. The input of a new Sector Erase command restarts the timeout
period.
The status of the internal timer can be monitored through the level of the Erase timeout Flag
bit (DQ3/DQ11). If the Erase timeout Flag bit (DQ3/DQ11) is 0, the Sector Erase instruction
has been received and the timeout period is counting. If the Erase timeout Flag bit
(DQ3/DQ11) is 1, the timeout period has expired and the PSD is busy erasing the Flash
memory sector(s). Before and during Erase timeout, any instruction other than Suspend
Sector Erase and Resume Sector Erase, abort the cycle that is currently in progress, and
reset 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.
During a Sector Erase, the memory status may be checked by reading the Error Flag bit
(DQ5/DQ13), the Toggle Flag bit (DQ6/DQ14), and the Data Polling bit (DQ7/DQ15), as
detailed in
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 resumed.
Section 9: Programming Flash
Section 9: Programming Flash
Table
memory. The Error Flag bit (DQ5/DQ13) returns a
memory.
29. If any byte of the Bulk Erase instruction is
Erasing Flash memory
Table
29.
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