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4 Mbit (x16) Multi-Purpose Flash
A Microchip Technology Company
SST39WF400B
Data Sheet
Write Operation Status Detection
To optimize the system write cycle time, the SST39WF400B provides two software means to detect the
completion of a Program or Erase write cycle. The software detection includes two status bits—Data#
Polling (DQ 7 ) and Toggle Bit (DQ 6 ). The End-of-Write detection mode is enabled after the rising edge
of WE#, which initiates the internal Program or Erase operation.
The completion of the nonvolatile Write is asynchronous with the system; therefore, either a Data#
Polling or Toggle Bit read may occur simultaneously with the completion of the Write cycle. If this
occurs, the system may get an erroneous result, i.e., valid data may appear to conflict with either DQ 7
or DQ 6 . To prevent spurious rejection in the event of an erroneous result, the software routine must
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.
Data# Polling (DQ 7 )
When the SST39WF400B is in the internal Program operation, any attempt to read DQ 7 will produce
the complement of the true data. Once the Program operation is complete, DQ 7 will produce true data.
Although DQ 7 may have valid data immediately following the completion of an internal Write operation,
the remaining data outputs may still be invalid. Valid data on the entire data bus will appear in subse-
quent successive Read cycles after an interval of 1 μs . During an internal Erase operation, any attempt
to read DQ 7 will produce a ‘0’. Once the internal Erase operation is complete, DQ 7 will produce a ‘1’.
The Data# Polling is valid after the rising edge of fourth WE# (or CE#) pulse for Program operation. For
Sector-, Block-, or Chip-Erase, the Data# Polling is valid after the rising edge of sixth WE# (or CE#)
pulse. See Figure 8 for Data# Polling timing diagram and Figure 19 for a flowchart.
Toggle Bit (DQ 6 )
During the internal Program or Erase operation, any consecutive attempts to read DQ 6 will produce
alternating ‘1’s and ‘0’s, i.e., toggling between ‘1’ and ‘0’.
When the Program or Erase operation is complete, the DQ 6 bit will stop toggling and the device is
ready for the next operation.
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 9 for Toggle Bit timing diagram and Figure 19 for a flowchart.
Data Protection
The SST39WF400B provides 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.
V DD Power Up/Down Detection: The Write operation is inhibited when V DD is less than 1.0V.
Write Inhibit Mode : Forcing OE# low, CE# high, or WE# high will inhibit the Write operation. This pre-
vents inadvertent writes during power-up or power-down.
?2011 Silicon Storage Technology, Inc.
8
DS25034A
09/11
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SST39WF800A-90-4C-B3KE 功能描述:闪存 8M (512Kx16) 90ns 1.65-1.95V Comm RoHS:否 制造商:ON Semiconductor 数据总线宽度:1 bit 存储类型:Flash 存储容量:2 MB 结构:256 K x 8 定时类型: 接口类型:SPI 访问时间: 电源电压-最大:3.6 V 电源电压-最小:2.3 V 最大工作电流:15 mA 工作温度:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体: 封装:Reel
SST39WF800A-90-4C-B3KE-T 功能描述:闪存 1.65 to 1.95V 8Mbit Multi-Purpose 闪存 RoHS:否 制造商:ON Semiconductor 数据总线宽度:1 bit 存储类型:Flash 存储容量:2 MB 结构:256 K x 8 定时类型: 接口类型:SPI 访问时间: 电源电压-最大:3.6 V 电源电压-最小:2.3 V 最大工作电流:15 mA 工作温度:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体: 封装:Reel
SST39WF800A-90-4C-C2QE 功能描述:闪存 512K x 16 90ns RoHS:否 制造商:ON Semiconductor 数据总线宽度:1 bit 存储类型:Flash 存储容量:2 MB 结构:256 K x 8 定时类型: 接口类型:SPI 访问时间: 电源电压-最大:3.6 V 电源电压-最小:2.3 V 最大工作电流:15 mA 工作温度:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体: 封装:Reel
SST39WF800A-90-4C-M2Q 功能描述:闪存 512K x 16 闪存 90ns 2KWord Sector RoHS:否 制造商:ON Semiconductor 数据总线宽度:1 bit 存储类型:Flash 存储容量:2 MB 结构:256 K x 8 定时类型: 接口类型:SPI 访问时间: 电源电压-最大:3.6 V 电源电压-最小:2.3 V 最大工作电流:15 mA 工作温度:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体: 封装:Reel
SST39WF800A-90-4C-M2QE 功能描述:闪存 512K X 16 FLASH RoHS:否 制造商:ON Semiconductor 数据总线宽度:1 bit 存储类型:Flash 存储容量:2 MB 结构:256 K x 8 定时类型: 接口类型:SPI 访问时间: 电源电压-最大:3.6 V 电源电压-最小:2.3 V 最大工作电流:15 mA 工作温度:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体: 封装:Reel
SST39WF800A-90-4C-M2QE-T 功能描述:闪存 1.65 to 1.95V 8Mbit Multi-Purpose 闪存 RoHS:否 制造商:ON Semiconductor 数据总线宽度:1 bit 存储类型:Flash 存储容量:2 MB 结构:256 K x 8 定时类型: 接口类型:SPI 访问时间: 电源电压-最大:3.6 V 电源电压-最小:2.3 V 最大工作电流:15 mA 工作温度:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体: 封装:Reel