SRI4K-A3T/1GE STMicroelectronics, SRI4K-A3T/1GE Datasheet - Page 13

• Manufacturer Part Number: SRI4K-A3T/1GE
• Manufacturer: STMicroelectronics

Specifications of SRI4K-A3T/1GE

• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Lead Free Status / Rohs Status: Compliant

System Area
This area is used to modify the settings of the
SRI4K. It contains 3 registers: OTP_Lock_Reg,
Fixed Chip_ID and ST Reserved. See
for a map of this area.
Figure 20. System Area
OTP_Lock_Reg. The 8 bits, b
System Area (block address 255) are used as
OTP_Lock_Reg bits in the SRI4K. They control
the Write access to the 9 EEPROM blocks with ad-
dresses 7 to 15 as follows:
–
–
–
–
–
–
–
–
The OTP_Lock_Reg bits cannot be erased. Once
Write-protected, EEPROM blocks behave like
ROM blocks and cannot be unprotected.
When b
protected
When b
When b
When b
When b
When b
When b
When b
Block
Address
24
25
26
27
28
29
30
31
255
is at 0, blocks 7 and 8 are Write-
is at 0, block 9 is Write-protected
is at 0, block 10 is Write-protected
is at 0, block 11 is Write-protected
is at 0, block 12 is Write-protected
is at 0, block 13 is Write-protected
is at 0, block 14 is Write-protected
is at 0, block 15 is Write-protected.
MSb
OTP_Lock_Reg
b31
b24 b23
31
to b
Figure 20.
24
, of the
ST Reserved
32-bit Block
b16 b15
A WRITE_BLOCK command in this area will not
erase the previous contents. Selected bits can
thus be set from 1 to 0. All bits previously at 0 re-
main unchanged. Once all the 32 bits of a block
are at 0, the block is empty and cannot be updated
any more.
Fixed Chip_ID (Option). The SRI4K is provided
with an anti-collision feature based on a random 8-
bit Chip_ID. Prior to selecting an SRI4K, an anti-
collision sequence has to be run to search for the
Chip_ID of the SRI4K. This is a very flexible fea-
ture, however the searching loop requires time to
run.
For some applications, much time could be saved
by knowing the value of the SRI4K Chip_ID be-
forehand, so that the SRI4K can be identified and
selected directly without having to run an anti-col-
lision sequence. This is why the SRI4K was de-
signed with an optional mask setting used to
program a fixed 8-bit Chip_ID to bits b
system area. When the fixed Chip_ID option is
used, the random Chip_ID function is disabled.
b8 b7
Fixed Chip_ID
(Option)
LSb
b0
Description
OTP
7
to b
ai07663
SRI4K
0
of the
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