SST39LF080 datasheet(3/26 Pages) SST

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Data Sheet

8 Mbit / 16 Mbit Multi-Purpose Flash

SST39LF080 / SST39LF016 / SST39VF080 / SST39VF016

S71146-03-000

6/01

396

The actual completion of the nonvolatile write is asynchro-

nous 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 con-

flict 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 rejec-

tion is valid.

Data# Polling (DQ7)

When the SST39LF/VF080 and SST39LF/VF016 are in

the internal Program operation, any attempt to read DQ7

will produce the complement of the true data. Once the

Program operation is completed, DQ7 will produce true

data. The device is then ready for the next operation. Dur-

ing internal Erase operation, any attempt to read DQ7 will

produce a ‘0’. Once the internal Erase operation is com-

pleted, DQ7 will produce a ‘1’. The Data# Polling is valid

after the rising edge of fourth WE# (or CE#) pulse for Pro-

gram operation. For Sector-, Block- or Chip-Erase, the

Data# Polling is valid after the rising edge of sixth WE# (or

CE#) pulse. See Figure 6 for Data# Polling timing diagram

and Figure 17 for a flowchart.

Toggle Bit (DQ6)

During the internal Program or Erase operation, any con-

secutive attempts to read DQ6 will produce alternating 1s

and 0s, i.e., toggling between 1 and 0. When the internal

Program or Erase operation is completed, the DQ6 bit will

stop toggling. The device is then ready for the next opera-

tion. The Toggle Bit is valid after the rising edge of fourth

WE# (or CE#) pulse for Program operation. For Sector-,

Block-, or Chip-Erase, the Toggle Bit is valid after the rising

edge of sixth WE# (or CE#) pulse. See Figure 7 for Toggle

Bit timing diagram and Figure 17 for a flowchart.

Data Protection

The SST39LF/VF080 and SST39LF/VF016 provide both

hardware and software features to protect nonvolatile data

from inadvertent writes.

Hardware Data Protection

Noise/Glitch Protection: A WE# or CE# pulse of less than 5

ns will not initiate a Write cycle.

VDD Power Up/Down Detection: The Write operation is

inhibited when VDD is less than 1.5V.

Write Inhibit Mode: Forcing OE# low, CE# high, or WE#

high will inhibit the Write operation. This prevents inadvert-

ent writes during power-up or power-down.

Software Data Protection (SDP)

The SST39LF/VF080 and SST39LF/VF016 provide the

JEDEC approved Software Data Protection scheme for all

data alteration operations, i.e., Program and Erase. Any

Program operation requires the inclusion of the three-byte

sequence. The three-byte load sequence is used to initiate

the Program operation, providing optimal protection from

inadvertent Write operations, e.g., during the system

power-up or power-down. Any Erase operation requires the

inclusion of six-byte sequence. The SST39LF/VF080 and

SST39LF/VF016 devices are shipped with the Software

Data Protection permanently enabled. See Table 4 for the

specific software command codes. During SDP command

sequence, invalid commands will abort the device to read

mode within TRC.

Common Flash Memory Interface (CFI)

The SST39LF/VF080 and SST39LF/VF016 also contain

the CFI information to describe the characteristics of the

device. In order to enter the CFI Query mode, the system

must write three-byte sequence, same as product ID entry

command with 98H (CFI Query command) to address

5555H in the last byte sequence. Once the device enters

the CFI Query mode, the system can read CFI data at the

addresses given in Tables 5 through 8. The system must

write the CFI Exit command to return to Read mode from

the CFI Query mode.

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