LTC4304_15 Datasheet, PDF (1/16 Pages) Linear Technology – Hot Swappable 2-Wire Bus Buffer with Stuck Bus Recovery

FEATURES
■ _{Automatic Disconnect of SDA/SCL Lines when Bus}
is Stuck Low for ≥30ms
■ _{Fault Flag for Stuck Bus}
■ _{Recovers Stuck Busses with Automatic Clocking*}
■ _{Bidirectional Buffer* for SDA and SCL Lines}
Increases Fanout
■ _{Prevents SDA and SCL Corruption During Live}
Board Insertion and Removal from Backplane
■ _{Allows Bus Pullup Voltages Above and Below VCC}
■ _{±15kV Human Body Model ESD Protection}
■ _{Isolates Input SDA and SCL Lines from Output}
■ _{Compatible with I}²_C^TM_{, I}²_{C Fast-Mode and SMBus}
Standards (Up to 400kHz Operation)
■ _{READY Open Drain Output}
■ _{1V Precharge on All SDA and SCL Lines}
■ _{High Impedance SDA, SCL Pins for VCC = 0V}
■ _{ENABLE Gates Connection from Input to Output}
■
MSOP
10-Pin
and DFN
U
(3mm
×
3mm)
Packages
APPLICATIO S
■ _{Hot Board Insertion}
■ _Servers
■ _{Capacitance Buffer/Bus Extender}
■ _{RAID Systems}
LTC4304
Hot Swappable 2-Wire
Bus Buffer with Stuck
Bus Recovery
DESCRIPTIO
The LTC^®4304 hot swappable 2-wire bus buffer allows I/O
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
SCL bus pull-up voltages below V_CC.
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.
, 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.
TYPICAL APPLICATIO
5V 3.3V
10k 10k
BACK_SCL
BACK_SDA
3.3V
SCLIN
V_CC
LTC4304
0.01µF
SCLOUT
10k 10k
CARD_SCL
SDAIN
SDAOUT
FAULT
ENABLE
GND
100k
READY
ACC
4304 TA01
CARD_SDA
SDAOUT
5V/DIV
SDAIN
5V/DIV
SCLOUT
5V/DIV
FAULT
5V/DIV
BACKPLANE STAGGERED
CONNECTOR CONNECTOR
CARD
Stuck Bus Resolved with
Automatic Clocking
STUCK LOW > 30ms
RECOVERS
DISCONNECT AT TIMEOUT
AUTOMATIC CLOCKING
200ms/DIV
4304 TA01b
4304fa
1