SST39VF6401B datasheet(7/38 Pages) MICROCHIP

7 / 38 page

DS20005008C

64 Mbit Multi-Purpose Flash Plus

SST39VF6401B / SST39VF6402B

Not Recommended for New Designs

for timing waveforms and Figure 24 for the flowchart. Any commands issued during the Sector- or

Block-Erase operation are ignored. When WP# is low, any attempt to Sector- (Block-) Erase the pro-

tected block will be ignored. During the command sequence, WP# should be statically held high or low.

Erase-Suspend/Erase-Resume Commands

The Erase-Suspend operation temporarily suspends a Sector- or Block-Erase operation thus allowing

data to be read from any memory location, or program data into any sector/block that is not suspended

for an Erase operation. The operation is executed by issuing one byte command sequence with Erase-

Suspend command (B0H). The device automatically enters read mode typically within 20 µs after the

Erase-Suspend command had been issued. Valid data can be read from any sector or block that is not

suspended from an Erase operation. Reading at address location within erase-suspended sectors/

blocks will output DQ2 toggling and DQ6 at “1”. While in Erase-Suspend mode, a Word-Program oper-

ation is allowed except for the sector or block selected for Erase-Suspend.

To resume Sector-Erase or Block-Erase operation which has been suspended the system must issue

Erase Resume command. The operation is executed by issuing one byte command sequence with

Erase Resume command (30H) at any address in the last Byte sequence.

Chip-Erase Operation

The SST39VF640xB provide a Chip-Erase operation, which allows the user to erase the entire mem-

ory array to the “1” state. This is useful when the entire device must be quickly erased.

The Chip-Erase operation is initiated by executing a six-byte command sequence with Chip-Erase

command (10H) at address 555H in the last byte sequence. The Erase operation begins with the rising

edge of the sixth WE# or CE#, whichever occurs first. During the Erase operation, the only valid read is

Toggle Bit or Data# Polling. See Table 6 for the command sequence, Figure 10 for timing diagram, and

Figure 24 for the flowchart. Any commands issued during the Chip-Erase operation are ignored. When

WP# is low, any attempt to Chip-Erase will be ignored. During the command sequence, WP# should

be statically held high or low.

Write Operation Status Detection

The SST39VF640xB provide two software means to detect the completion of a Write (Program or

Erase) cycle, in order to optimize the system write cycle time. The software detection includes two sta-

tus bits: Data# Polling (DQ7) and Toggle Bit (DQ6). The End-of-Write detection mode is enabled after

the rising edge of WE#, which initiates the internal Program or Erase operation.

The actual completion of the nonvolatile write is asynchronous with the system; therefore, either a

Data# Polling or Toggle Bit read may be simultaneous with the completion of the write cycle. If this

occurs, the system may possibly get an erroneous result, i.e., valid data may appear to conflict with

either DQ7 or DQ6. In order to prevent spurious rejection, if an erroneous result occurs, the software

routine should include a loop to read the accessed location an additional two (2) times. If both reads

are valid, then the device has completed the Write cycle, otherwise the rejection is valid.

SST39VF6401B Datasheet(PDF) 7 Page - Microchip Technology