ADM1063ASU datasheet(29/36 Pages) AD

29 / 36 page

ADM1063

Rev. 0 | Page 29 of 36

START BY

MASTER

ACK. BY

SLAVE

ACK. BY

MASTER

ACK. BY

MASTER

NO ACK.

FRAME 2

DATA BYTE

FRAME 1

SLAVE ADDRESS

FRAME N

DATA BYTE

FRAME 3

DATA BYTE

SCL

SDA

R/W

STOP

MASTER

SCL

(CONTINUED)

SDA

(CONTINUED)

Figure 40. General SMBus Read Timing Diagram

SCL

SDA

t SU;STO

t HD;STA

t SU;STA

t SU;DAT

t HD;DAT

t HD;STA

t HIGH

t BUF

t LOW

t R

t F

Figure 41. Serial Bus Timing Diagram

SMBus PROTOCOLS FOR RAM AND EEPROM

The ADM1063 contains volatile registers (RAM) and nonvola-

tile registers (EEPROM). User RAM occupies address locations

from 0x00 to 0xDF; EEPROM occupies addresses from 0xF800

to 0xFBFF.

Data can be written to and read from both RAM and EEPROM

as single data bytes. Data can be written only to unprogrammed

EEPROM locations. To write new data to a programmed location,

the location’s contents must first be erased. EEPROM erasure

cannot be done at the byte level. The EEPROM is arranged as

32 pages of 32 bytes each, and an entire page must be erased.

Page erasure is enabled by setting Bit 2 in the UPDCFG register

(Address 0x90) to 1. If this bit is not set, page erasure cannot

occur, even if the command byte (0xFE) is programmed across

the SMBus.

WRITE OPERATIONS

The SMBus specification defines several protocols for different

types of read and write operations. The following abbreviations

are used in the diagrams:

S = Start

P = Stop

R = Read

W= Write

A = Acknowledge

A = No acknowledge

The ADM1063 uses the following SMBus write protocols.

Send Byte

In a send byte operation, the master device sends a single

command byte to a slave device, as follows:

The master device asserts a start condition on SDA.

The master sends the 7-bit slave address followed by the

write bit (low).

The addressed slave device asserts ACK on SDA.

The master sends a command code.

The slave asserts ACK on SDA.

The master asserts a stop condition on SDA, and the

transaction ends.

In the ADM1063, the send byte protocol is used for two purposes:

•

To write a register address to RAM for a subsequent single

byte read from the same address, or for a block read or a

block write starting at that address, as shown in Figure 42.

SLAVE

ADDRESS

RAM

ADDRESS

(0x00 TO 0xDF)

Figure 42. Setting a RAM Address for Subsequent Read

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