LM93 datasheet(22/95 Pages) TI1

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LM93

SNAS210E – DECEMBER 2003 – REVISED MARCH 2013

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3.15.4 SMBUS ERROR SAFETY FEATURES

To provide a more robust SMBus interface, the LM93 incorporates a timeout feature for both SMBCLK

and SMBDAT. If either signal is low for a long period of time (see SMBus AC Characteristics), the LM93

SMBus state machine reverts to the idle state and waits for a START signal. Large block transfers of all

zeros should be avoided if the SMBCLK is operating at a very low frequency to avoid accidental timeouts.

Pulling the Reset pin low does not reset the SMBus state machine. If the LM93 SMBDAT pin is low during

a system reset, the LM93’s state machine timeouts and resets automatically. If the LM93’s SMBDAT pin is

high during a system reset, the first assertion of a start by the master resets the LM93’s interface state

machine.

Although it is a violation of the SMBus specification, in some cases a START or STOP signal occurs in the

middle of a byte transfer instead of coming after an acknowledge bit. If this occurs, only a partial byte was

transferred. If a byte was being written, it is aborted and the partial byte is not committed. If a byte was

being read from a read-to-clear register, the register is not cleared.

3.15.5 SERIAL INTERFACE PROTOCOLS

The LM93 contains volatile registers, the registers occupy address locations from 00h to EFh.

Data can be read and written as a single byte, a word, or as a block of several bytes. The LM93 supports

the following SMBus/I2C transactions/protocols:

— Send Byte

— Write Byte

— Write Word

— SMBus Write Block

— I2C Block Write

— Read Byte

— Read Word

— SMBus Read Block

— SMBus Block-Write Block-Read Process Call

— I2C Block Read

In addition to these transactions the LM93 supports a few extra items and also has some behavior that

must be defined beyond the SMBus 2.0 specification. No other SMBus 2.0 transactions are supported

(PEC, ARA etc.).

The SMBus specification defines several protocols for different types of read and write operations. The

ones used in the LM93 are discussed below. The following abbreviations are used in the diagrams:

S — START

P — STOP

R — READ

W — WRITE

A — ACKNOWLEDGE

/A — NO ACKNOWLEDGE

Functional Description

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