LTC4305

1

4305f

APPLICATIO S

TYPICAL APPLICATIO

FEATURES

DESCRIPTIO

The LTC

bus buffers to provide capacitive isolation between the

upstream bus and downstream buses. Through software

control, the LTC4305 connects the upstream 2-wire bus

to any desired combination of downstream channels.

Each channel can be pulled up to a supply voltage ranging

from 2.2V to 5.5V, independent of the LTC4305 supply

voltage. The downstream channels are also provided with

an ALERT1–ALERT2 inputs for fault reporting.

Programmable timeout circuitry disconnects the down-

stream buses if the bus is stuck low. When activated, rise

time accelerators source currents into the 2-wire bus pins

to reduce rise time. Driving the ENABLE pin low restores

all features to their default states. Three address pins

provide 27 distinct addresses.

The LTC4305 is available in 16-lead (4mm

× 5mm) DFN

and SSOP packages.

■

Nested Addressing

■

5V/3.3V Level Translator

■

Capacitance Buffer/Bus Extender

■

1:2 2-Wire Multiplexer/Switch

■

Connect SDA and SCL Lines with 2-Wire Bus

Commands

■

Supply Independent Bidirectional Buffer for SDA

and SCL Lines Increases Fan-Out

■

Programmable Disconnect from Stuck Bus

■

■

Rise Time Accelerator Circuitry

■

SMBus Compatible ALERT Response Protocol

■

Prevents SDA and SCL Corruption During Live Board

Insertion and Removal from Backplane

■

±10kV Human Body Model ESD Ruggedness

■

16-Lead (4mm

× 5mm) DFN and SSOP Packages

2-Channel,

2-Wire Bus Multiplexer with

Capacitance Buffering

, LTC and LT are registered trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners. Patent Pending.

A Level-Shifting and Nested Addressing Application

10k

0.01

µF

10k

10k

10k

10k

10k

ADDRESS = 1000 100

SFP

MODULE #1

10k

10k

10k

ADDRESS = 1111 000

MICRO-

CONTROLLER

SFP

MODULE #2

ADDRESS = 1111 000

2.5V

5V

3.3V

4305 TA01

SCLIN

SDAIN

ALERT

ADR2

ADR1

ADR0

GND

SCL1

SDA1

ALERT1

SCL2

SDA2

ALERT2

LTC4305

4305 TA01b

VCARD1 = 3.3V

VCARD2 = 5V

VBACK = 2.5V

SCL2

2V/DIV

500ns/DIV

SCL1

2V/DIV

SCLIN

2V/DIV