Data Sheet

ZL40293

ZL40293

March 2019

© 2019 Microsemi Corporation

13

Programming via SMBus

The address selection is done via SA_0 and SA_1 tri-level hardware pins, which select the appropriate address for

the device. The two tri-level input pins that can configure the ZL40293 to nine different addresses (refer to Table 15

for VIL_Tri, VIM_Tri, VIH_Tri signal level).

Table 4 SMBus Address Table

SA_1

SA_0

SMBus Address

L

L

D8

L

M

DA

L

H

DE

M

L

C2

M

M

C4

M

H

C6

H

L

CA

H

M

CC

H

H

CE

SMBus Byte Read/Write

Reading or writing a register in a SMBus slave device in byte mode always involves specifying the register number.

Read. The standard byte read is as shown in Figure 11. It is an extension of the byte write. The write start condition is

repeated then the slave device starts sending data and the master acknowledges it until the last byte is sent. The

master terminates the transfer with a NAK then a stop condition. For byte operation, the 2*7th bit of the command byte

must be set. For block operations, the 2*7th bit must be reset. If the bit is not set, the next byte must be the byte

transfer count.

Figure 11.

SMBus Byte Read

T

Slave

Command

r

Slave

A

N

P

Wr

Rd

StarT

Condition

Command

Register #

to read

2*7 bit = 1

repeat starT

Acknowledge

Not ack

stoP

Condition

Master

drive Bus

Slave

drive Bus

1

7

1

1

8

1

1

8

1

1

8

1

1

A

A

Data Byte 0