DS1961S-F5 Maxim Integrated Products, DS1961S-F5 Datasheet - Page 32

• Manufacturer Part Number: DS1961S-F5
• Description: DS1961S 1kb Protected EePROM Ibutton With SHA-1 Engine
• Manufacturer: Maxim Integrated Products

Figure 11. READ/WRITE TIMING DIAGRAMS
Write-One Time Slot
Write-Zero Time Slot
Read-Data Time Slot
CRC GENERATION
With the DS1961S there are two different types of CRCs. One CRC is an 8-bit type. It is computed at the
factory and lasered into the most significant byte of the 64-bit ROM. The equivalent polynomial function
of this CRC is X
master can compute the CRC value from the first 56 bits of the 64-bit ROM and compare it to the value
V
V
V
IHMASTER
IHMASTER
IHMASTER
V
V
V
V
V
ILMAX
ILMAX
V
ILMAX
V
V
V
V
V
V
PUP
PUP
PUP
0V
0V
0V
TH
TH
TH
TL
TL
TL
8
+ X
t
F
t
t
F
F
5
+ X
RESISTOR
RESISTOR
RESISTOR
4
t
RL
+ 1. To determine whether the ROM data has been read without error the bus
t
W1L
t
t
SLSMIN
SLSMIN
e
d
t
W0L
t
Sampling
SPDMIN
Window
Master
t
MSR
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MASTER
MASTER
MASTER
t
DS1961S
Sampling
DS1961S
Sampling
SLSMAX
Window
Window
t
SLSMAX
t
SPDMAX
t
SLOT
t
t
REC
SLOT
t
REC
DS1961S
DS1961S
DS1961S
t
SLOT
t
REC