DS28CM00: I²C/SMBus Silicon Serial Number

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I²C Communication

⎯Legend

SYMBOL

DESCRIPTION

SYMBOL

DESCRIPTION

S

START Condition

A

Acknowledged

AD,0

Select DS28CM00 for Write Access

A\

Not Acknowledged

AD,1

Select DS28CM00 for Read Access

<byte>

Transfer of One Byte

Sr

Repeated START Condition

VMA

Valid Memory Address (00h to 08h)

P

STOP Condition

IMA

Invalid Memory Address

Command-Specific Communication

⎯Color-Codes

Master-to-Slave

Slave-to-Master

Communication Examples

Write to Control Register (address 08)

S

AD,0

A

08h

A

<byte>

A

P

Write to ROM Address (excludes address 08)

S

AD,0

A

VMA

A

<byte>

A\

P

Write to invalid address (>08)

S

AD,0

A

IMA

A\

P

Read

S

AD,0

A

VMA

A

Sr

AD,1

A

<byte>

A

<byte>

A\

P

Application Information

SDA and SCL Pullup Resistors

SDA is an open-drain output on the DS28CM00 that requires a pullup resistor (Figure 6) to realize high logic levels.

Because the DS28CM00 uses SCL only as input (no clock stretching) the master can drive SCL either through an

open-drain/collector output with a pullup resistor or a push-pull output.

over its entire operating voltage range. This DC characteristic determines the minimum value of the pullup resistor:

is 1.2k

Ω. The "Minimum RP" line in Figure 7 shows how the minimum pullup resistor changes with the operating

(pullup) voltage.

last byte

one or

more bytes

data is not accepted

address is not accepted

Set address pointer