 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
SST39WF400A-90-4C-C1Q Datasheet(PDF) 2 Page - Silicon Storage Technology, Inc |
|
||||||||||||||||||||||||||||||
SST39WF400A-90-4C-C1Q Datasheet(HTML) 2 Page - Silicon Storage Technology, Inc |
|
|
2 / 26 page  2 Data Sheet 4 Mbit Multi-Purpose Flash SST39WF400A ©2003 Silicon Storage Technology, Inc. S71220-04-000 11/03 Device Operation Commands are used to initiate the memory operation func- tions of the device. Commands are written to the device using standard microprocessor write sequences. A com- mand is written by asserting WE# low while keeping CE# low. The address bus is latched on the falling edge of WE# or CE#, whichever occurs last. The data bus is latched on the rising edge of WE# or CE#, whichever occurs first. Read The Read operation of the SST39WF400A is controlled by CE# and OE#, both have to be low for the system to obtain data from the outputs. CE# is used for device selection. When CE# is high, the chip is deselected and only standby power is consumed. OE# is the output control and is used to gate data from the output pins. The data bus is in high impedance state when either CE# or OE# is high. Refer to the Read cycle timing diagram for further details (Figure 3). Word-Program Operation The SST39WF400A is programmed on a word-by-word basis. Before programming, the sector where the word exists must be fully erased. The Program operation is accomplished in three steps. The first step is the three-byte load sequence for Software Data Protection. The second step is to load word address and word data. During the Word-Program operation, the addresses are latched on the falling edge of either CE# or WE#, whichever occurs last. The data is latched on the rising edge of either CE# or WE#, whichever occurs first. The third step is the internal Program operation which is initiated after the rising edge of the fourth WE# or CE#, whichever occurs first. The Pro- gram operation, once initiated, will be completed within 40 µs. See Figures 4 and 5 for WE# and CE# controlled Pro- gram operation timing diagrams and Figure 16 for flow- charts. During the Program operation, the only valid reads are Data# Polling and Toggle Bit. During the internal Pro- gram operation, the host is free to perform additional tasks. Any commands issued during the internal Program opera- tion are ignored. Sector/Block-Erase Operation The Sector- (or Block-) Erase operation allows the system to erase the device on a sector-by-sector (or block-by- block) basis. The SST39WF400A offers both Sector-Erase and Block-Erase mode. The sector architecture is based on uniform sector size of 2 KWord. The Block-Erase mode is based on uniform block size of 32 KWord. The Sector- Erase operation is initiated by executing a six-byte com- mand sequence with Sector-Erase command (30H) and sector address (SA) in the last bus cycle. The Block-Erase operation is initiated by executing a six-byte command sequence with Block-Erase command (50H) and block address (BA) in the last bus cycle. The sector or block address is latched on the falling edge of the sixth WE# pulse, while the command (30H or 50H) is latched on the rising edge of the sixth WE# pulse. The internal Erase operation begins after the sixth WE# pulse. The End-of- Erase operation can be determined using either Data# Polling or Toggle Bit methods. See Figures 9 and 10 for tim- ing waveforms. Any commands issued during the Sector- or Block-Erase operation are ignored. Chip-Erase Operation The SST39WF400A provides a Chip-Erase operation, which allows the user to erase the entire memory 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 5555H 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 4 for the command sequence, Figure 8 for timing diagram, and Figure 19 for the flowchart. Any commands issued dur- ing the Chip-Erase operation are ignored. Write Operation Status Detection The SST39WF400A provides two software means to detect the completion of a write (Program or Erase) cycle, in order to optimize the system write cycle time. The soft- ware detection includes two status bits: Data# Polling (DQ7) and Toggle Bit (DQ6). The End-of-Write detection mode is enabled after the rising edge of WE#, which ini- tiates the internal Program or Erase operation. 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. |
Similar Part No. - SST39WF400A-90-4C-C1Q |
|
Similar Description - SST39WF400A-90-4C-C1Q |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
