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May 12, 2010

IDT Confidential

I2C Operating Modes

Device Reset and Initialization

In order to prevent inadvertent Write operations during Power-up, a Power-On Reset (POR) circuit is included.

At Power-up (phase during which VDDSPD is lower than VDDSPDmin but increases continuously), the device will not respond to any instruction until

VDDSPD has reached the Power On Reset threshold voltage (this threshold is lower than the minimum VDDSPD operating voltage defined in the DC

AND AC PARAMETERS tables). Once VDDSPD has passed the POR threshold, the device is reset. The actual POR threshold voltage will be imple-

mentation dependent and is not defined in this document.

The device is delivered with all bits in the EEPROM memory array set to ' 1' (each byte contains 0xFF).

Prior to selecting the memory and issuing instructions, a valid and stable VDDSPD voltage must be applied. This voltage must remain stable and

valid until the end of the transmission of the instruction and for a Write instruction, until the completion of the internal write cycle (tW).

At Power-down (phase during which VDDSPD decreases continuously), as soon as VDDSPD drops below the minimum operating voltage, the device

stops responding to commands, and remains in reset until the POR threshold voltage is reached.

Mode

R/W# Bit

Bytes

Initial Sequence

SPD Current Address Read

1

1

START, Device Select, R/W# = 1

SPD Random Address Read

0

1

START, Device Select, R/W# = 0, Address

1

reSTART, Device Select, R/W# = 1

SPD Sequential Read

1

> 1

Similar to Current or Random Address Read

SPD Byte Write

0

1

START, Device Select, R/W# = 0, data, STOP

SPD Page Write

0

< 16

START, Device Select, R/W# = 0, data, STOP

TS Write

0

2

START, Device Select, R/W#=0, pointer, data, STOP

TS Read

1

2

START, Device Select, R/W#=1, pointer, data, STOP