MAX4584 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX4584

Serially Controlled Audio/Video Switches

Maxim Integrated 

Table 1. Command-Bit Mapping

COMMAND

BIT

SWITCH

TERMINALS

D7 (MSB)

X

—

D6

X

—

D5

X

—

D4

X

—

D3

X

—

D2

NO2 to COM2

6, 7

D1

NO1B to COM1

9, 1

D0 (LSB) NO1A to COM1 10, 1

X = Don’t care

POWER-UP

STATE

X

X

X

X

X

0 (Open)

1 (Closed)

0 (Open)

Serially Controlled

Audio/Video Switches

Table 2. Truth Table

LOGIC

0

1

NO1_ AND NO2

OPEN

CLOSED

Table 3. Address Bit Map

ADDRESS BIT (A)

0

1

ADDRESS

0110 1010

0110 1110

SLAVE ADDRESS BYTE

COMMAND BYTE

SDA

MSB

SCL

LSB ACK MSB

LSB ACK

START CONDITION

STOP CONDITION

Figure 2. A Complete 2-Wire Serial-Interface Transmission

es the associated switch (Table 2). A logic “0” in any

data-bit location opens the associated switch.

2-Wire Serial Interface

The MAX4584 uses a 2-wire I2C-compatible serial inter-

face. The COM_ register uses the “SendByte” protocol,

which consists of an address byte followed by a com-

mand byte (Table 1).

To address a given IC, bit A in the address byte must

duplicate the value present at the A pin of that IC. The

rest of the address bits must match those shown in

Table 3. The command byte details are described in

the Switch Control section.

The 2-wire serial interface requires only two I/O lines of

a standard microprocessor (µP) port. Figures 1 and 2

detail the timing diagram for signals on the 2-wire bus,

and Tables 1 and 3 detail the format of the signals. The

MAX4584 is a receive-only device and must be con-

trolled by the bus master device. A bus master device

communicates by transmitting the address byte of the

slave device over the bus and then transmitting the

desired information. Each transmission consists of a

start condition, an address byte, a command byte, and

finally a stop condition. The slave device acknowledges

the recognition of its address by pulling the SDA line

low for one clock period after the address byte is trans-

mitted. The slave device also issues a similar acknowl-

edgment after the command byte.

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 is then free for another

transmission.

Slave Address (Address Byte)

The MAX4584 uses an 8-bit-long slave address. To

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

MAX4584 has two possible slave addresses, so a maxi-

mum of two of these devices may share the same

address line. The slave device MAX4584 monitors the

serial bus continuously, waiting for a start condition fol-

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

nizes its address (01101A10), it acknowledges that it is

ready for further communication by pulling the SDA line

low for one clock period.

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