Start and Stop Conditions

The bus master signals the beginning of a transmission

with a start condition by transitioning SDA from high to

low while SCL is high. When the bus master has fin-

ished communicating with the slave device, it issues a

stop condition by transitioning SDA from low to high

while SCL is high. The bus master is then free for

another transmission.

Slave Address (Address Byte)

The MAX4586 uses an 8-bit-long slave address. To

select a slave address, connect A to V+ or GND. The

MAX4586 has two possible slave addresses, so a maxi-

mum of two of these devices may share the same

address line. The slave device MAX4586 monitors the

serial bus continuously, waiting for a start condition fol-

lowed by an address byte. When a slave device recog-

Serially Controlled, 4-Channel

Audio/Video Multiplexers

_______________________________________________________________________________________

9

SCL

SDA

START CONDITION

STOP CONDITION

REPEATED START CONDITION

START CONDITION

20%

70%

20%

70%

20%

70%

20%

70%

20%

70%

20%

70%

20%

70%

70%

20%

70%

70%

70%

Figure 1. 2-Wire Serial-Interface Timing Diagram

Table 1. Command-Bit Mapping

Table 3. Address Bit Map

Table 2. Truth Table

x

x

D4

x

x

D5

x

x

D6

x

x

D7 (MSB)

POWER-UP

STATE

TERMINALS

SWITCH

COMMAND

BIT

0 (Open)

6, 1

NO1 to COM

D0 (LSB)

0 (Open)

7, 1

NO2 to COM

D1

0 (Open)

9, 1

NO3 to COM

D2

0 (Open)

10, 1

NO4 to COM

D3

CLOSED

1

OPEN

0

NO_ SWITCH

LOGIC

0110 1110

1

0110 1010

0

ADDRESS

ADDRESS BIT (A)

START CONDITION

STOP CONDITION

COMMAND BYTE

SLAVE ADDRESS BYTE

SCL

SDA

MSB

MSB

LSB

LSB

ACK

ACK

Figure 2. Complete 2-Wire Serial-Interface Transmission

X = Don’t care