M29F400 データシートの表示（PDF） - STMicroelectronics
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M29F400 Datasheet PDF : 40 Pages
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Bus operations
M29F400BT, M29F400BB
3.5
Automatic Standby
If CMOS levels (VCC ± 0.2V) are used to drive the bus and the bus is inactive for 150ns or
more the memory enters Automatic Standby where the internal Supply Current is reduced to
the CMOS Standby Supply Current, ICC3. The Data Inputs/Outputs will still output data if a
Bus Read operation is in progress.
3.6
3.6.1
3.6.2
Special bus operations
Additional bus operations can be performed to read the Electronic Signature and also to
apply and remove Block Protection. These bus operations are intended for use by
programming equipment and are not usually used in applications. They require VID to be
applied to some pins.
Electronic Signature
The memory has two codes, the manufacturer code and the device code, that can be read
to identify the memory. These codes can be read by applying the signals listed in Table 2.
and Table 3., Bus Operations.
Block Protection and Blocks Unprotection
Each block can be separately protected against accidental Program or Erase. Protected
blocks can be unprotected to allow data to be changed.
There are two methods available for protecting and unprotecting the blocks, one for use on
programming equipment and the other for in-system use. For further information refer to
Application Note AN1122, Applying Protection and Unprotection to M29 Series Flash.
Table 2. Bus operations, BYTE = VIL(1)
Operation
E
GW
Address Inputs
DQ15A–1, A0-A17
Data Inputs/Outputs
DQ14-DQ8
DQ7-DQ0
Bus Read
VIL VIL VIH Cell Address
Bus Write
VIL VIH VIL Command Address
Output Disable
X VIH VIH X
Standby
VIH X X X
Read Manufacturer
Code
VIL
VIL
VIH
A0 = VIL, A1 = VIL, A9
= VID, Others VIL or VIH
Read Device Code
VIL
VIL
VIH
A0 = VIH, A1 = VIL, A9
= VID, Others VIL or VIH
1. X = VIL or VIH.
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Data Output
Data Input
Hi-Z
Hi-Z
20h
D5h (M29F400BT)
D6h (M29F400BB)
14/40
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