PSD4235G2-90U STMicroelectronics, PSD4235G2-90U Datasheet - Page 42

• 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

Instructions
8.9
8.10
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new READ or WRITE operation. The cycle is finished when two successive READs yield the
same output data.
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Error flag (DQ5) - DQ13 for Motorola
During a normal Program or Erase cycle, the Error Flag bit (DQ5/DQ13) is reset to '0.' This
bit is set to ’1’ when there is a failure during a Flash memory Program, Sector Erase, or Bulk
Erase cycle.
In the case of Flash memory programming, the Error Flag bit (DQ5/DQ13) indicates the
attempt to program a Flash memory bit, or bits, from the programmed state, 0, to the erased
state, 1, which is not a valid operation. The Error Flag bit (DQ5/DQ13) may also indicate a
timeout condition while attempting to program a word.
In case of an error in a Flash memory Sector Erase or Word Program cycle, the Flash
memory sector in which the error occurred or to which the programmed location belongs
must no longer be used. Other Flash memory sectors may still be used. The Error Flag bit
(DQ5/DQ13) is reset after a Reset instruction. A Reset instruction is required after detecting
an error on the Error Flag bit (DQ5/DQ13).
Erase timeout flag (DQ3) - DQ11 for Motorola
The Erase timeout Flag bit (DQ3/DQ11) reflects the timeout period allowed between two
consecutive Sector Erase instructions. The Erase timeout Flag bit (DQ3/DQ11) is reset to ’0’
after a Sector Erase cycle for a period of 100 µs + 20% unless an additional Sector Erase
instruction is decoded. After this period, or when the additional Sector Erase instruction is
decoded, the Erase timeout flag (DQ3/DQ11) bit is set to 1.
The Toggle Flag bit (DQ6/DQ14) is effective after the fourth WRITE pulse (for a
Program instruction) or after the sixth WRITE pulse (for an Erase instruction).
If the location to be programmed belongs to a protected Flash memory sector, the
instruction is ignored.
If all the Flash memory sectors selected for erasure are protected, the Toggle Flag bit
(DQ6/DQ14) toggles to ’0’ for about 100 µs and then returns to the value from the
previously addressed location.
PSD4235G2