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M29W256GL 参数 Datasheet PDF下载

M29W256GL图片预览
型号: M29W256GL
PDF下载: 下载PDF文件 查看货源
内容描述: 并行NOR闪存的嵌入式存储器 [Parallel NOR Flash Embedded Memory]
分类和应用: 闪存存储
文件页数/大小: 89 页 / 1158 K
品牌: MICRON [ MICRON TECHNOLOGY ]
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256Mb: 3V Embedded Parallel NOR Flash  
Device Protection  
Device Protection  
Hardware Protection  
The VPP/WP# function provides a hardware method of protecting the highest or lowest  
block. When VPP/WP# is LOW, PROGRAM and ERASE operations on either of these  
blocks is ignored to provide protection. When VPP/WP# is HIGH, the device reverts to  
the previous protection status for the highest or lowest block. PROGRAM and ERASE  
operations can modify the data in this block unless the block is protected using block  
protection.  
When VPP/write protect is raised to VPPH, the device automatically enters the unlock  
bypass mode, and command execution time is faster. This must never be done from any  
mode except read mode; otherwise the device might be left in an indeterminate state.  
A 0.1 μF capacitor should be connected between the VPP/write protect pin and the VSS  
ground pin to decouple the current surges from the power supply. The PCB track widths  
must be sufficient to carry the currents required during unlock bypass program.  
When VPP/write protect returns to HIGH or LOW, normal operation resumes. When op-  
erations execute in unlock bypass mode, the device draws IPP from the pin to supply  
the programming circuits. Transitions from HIGH to VPPH and from VPPH to LOW  
must be slower than tVHVPP.  
Note: Micron highly recommends driving VPP/WP# HIGH or LOW. If a system needs to  
float the VPP/WP# pin, without a pull-up/pull-down resistor and no capacitor, then an  
internal pull-up resistor is enabled.  
Table 14: VPP/WP# Functions  
VPP/WP# Settings  
Function  
VIL  
VIH  
Highest (29WxxxGH) or lowest (29WxxxGL) block is protected.  
Highest or lowest block is unprotected unless software protection is activated.  
Unlock bypass mode supplies current necessary to speed up PROGRAM execution time.  
VPPH  
Software Protection  
Software protection includes volatile, nonvolatile, and password protection as well as  
password access. The device is shipped with all blocks unprotected. On first use, the de-  
vice defaults to the nonvolatile protection mode but can be activated in either the non-  
volatile protection or password protection mode.  
The desired protection mode is activated by setting either the nonvolatile protection  
mode lock bit or the password protection mode lock bit of the lock register (see the Lock  
Register section). Both bits are one-time-programmable and nonvolatile; therefore, af-  
ter the protection mode has been activated, it cannot be changed, and the device is set  
permanently to operate in the selected protection mode. It is recommended that the  
desired software protection mode be activated when first programming the device.  
For the lowest and highest blocks, a higher level of block protection can be achieved by  
locking the blocks using nonvolatile protection mode and holding VPP /WP# LOW.  
PDF: 09005aef84bd3b68  
m29w_256mb.pdf - Rev. B 5/13 EN  
Micron Technology, Inc. reserves the right to change products or specifications without notice.  
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© 2013 Micron Technology, Inc. All rights reserved.