LTC4304

1

4304fa

Hot Swappable 2-Wire

Bus Buffer with Stuck

Bus Recovery

card insertion into a live backplane without corruption of

the data and clock busses. When a connection is made,

the LTC4304 provides bidirectional buffering, keeping the

backplane and card capacitances isolated. If SDAOUT or

SCLOUT is low for ≥30ms (typ), the LTC4304 automatically

breaks the data and clock bus connection and FAULT will

pull low. At this time the LTC4304 automatically generates

up to 16 clock pulses on SCLOUT in an attempt to free the

bus. A connection will be enabled automatically when the

bus becomes free. A logic low on the ACC input enables

the LTC4304’s rise-time accelerators. A logic high on ACC

disables the rise-time accelerators, which allows SDA and

During insertion, the SDA and SCL lines are precharged

to 1V to minimize bus disturbances. When driven high,

ENABLE allows the LTC4304 to connect after a stop bit or

bus idle occurs. Driving ENABLE low breaks the connection

between SDAIN and SDAOUT, SCLIN and SCLOUT. READY

is an open drain output that indicates when the backplane

and card sides are connected together.

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Automatic Disconnect of SDA/SCL Lines when Bus

is Stuck Low for ≥30ms

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Fault Flag for Stuck Bus

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Recovers Stuck Busses with Automatic Clocking*

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Bidirectional Buffer* for SDA and SCL Lines

Increases Fanout

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Prevents SDA and SCL Corruption During Live

Board Insertion and Removal from Backplane

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±15kV Human Body Model ESD Protection

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Isolates Input SDA and SCL Lines from Output

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Standards (Up to 400kHz Operation)

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READY Open Drain Output

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1V Precharge on All SDA and SCL Lines

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ENABLE Gates Connection from Input to Output

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MSOP 10-Pin and DFN (3mm × 3mm) Packages

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Hot Board Insertion

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Servers

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Capacitance Buffer/Bus Extender

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RAID Systems

CARD

100k

ENABLE

FAULT

CARD_SCL

CARD_SDA

SCLOUT

SCLIN

SDAOUT

READY

SDAIN

GND

LTC4304

ACC

0.01

µF

10k

10k

10k

10k

5V

BACK_SCL

BACKPLANE

CONNECTOR

BACK_SDA

3.3V

3.3V

STAGGERED

CONNECTOR

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

All other trademarks are the property of their respective owners.

Protected by U.S. Patents including 6356140, 6650174, 7032051.

SDAOUT

5V/DIV

SCLOUT

5V/DIV

FAULT

5V/DIV

200

ms/DIV

STUCK LOW > 30ms

RECOVERS

DISCONNECT AT TIMEOUT

AUTOMATIC CLOCKING

4304 TA01b

SDAIN

5V/DIV

Stuck Bus Resolved with

Automatic Clocking

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

APPLICATIO S