DS28CM00 Maxim, DS28CM00 Datasheet - Page 4

• Manufacturer Part Number: DS28CM00
• Description: The DS28CM00 is a low-cost, electronic registration number to provide an absolutely unique identity that can be determined with the industry standard I²C and SMBus&#8482 interface
• Manufacturer: Maxim

Figure 1. Block Diagram
Figure 2. Memory Map
Unique Registration Number
Each DS28CM00 has a unique Registration Number that is 64 bits long. The registration number begins with the
family code at address 00h followed by the 48-bit serial number (LS-byte at the lower address) and ends at
address 07h with the CRC (Cyclic Redundancy Check) of the first 56 bits. This CRC is generated using the
polynomial X
Registration Number is not related to the I²C slave address of the device.
Control Register
The Control Register at address 08h allows switching between I²C mode and SMBus mode. Only the LS bit of this
register, referred to as the CM bit, has a function. The other 7 bits always read 0 and cannot be changed. When the
CM bit is set to 1 (power-on default), the device is in SMBus mode, which enables the bus timeout function. Setting
the CM bit to 0 puts the device in I²C mode, where the timeout function is disabled. In SMBus mode, the serial
interface times out and is internally reset if SCL is stuck (high or low) or if SDA is stuck low for the duration of
t
communication start condition.
TIMEOUT
ADDR
08h
or longer. This reset turns the SDA line into an input, ensuring that the device is ready to recognize a
ADDRESS
8
00h
01h
02h
03h
04h
05h
06h
07h
08h
+ X
b7
0
5
+ X
4
+ 1. Additional information about CRCs is available in
b6
SCL
SDA
0
SRAM
TYPE
ROM
ROM
ROM
ROM
ROM
ROM
ROM
ROM
b5
0
ACCESS
Read
Read
Read
Read
Read
Read
Read
Read
R/W
Interface
b4
0
Serial
4 of 9
V
CC
GND
b3
CRC of Family Code and 48-bit Serial Number
0
DS28CM00: I²C/SMBus Silicon Serial Number
Serial Number, bits 16 to 23
Serial Number, bits 24 to 31
Serial Number, bits 32 to 39
Serial Number, bits 40 to 47
Serial Number, bits 8 to 15
Device Family Code (70h)
Serial Number, bits 0 to 7
b2
0
Registration
Register
Number
Control
Control Register
DESCRIPTION
ROM
b1
Application Note
0
CM
b0
27. The ROM