LTC4300A-1/LTC4300A-2
Hot Swappable
2-Wire Bus Buffers
FEATURES
DESCRIPTION
The LTC®4300A series hot swappable 2-wire bus buffers
allowI/Ocardinsertionintoalivebackplanewithoutcorrup-
tion of the data and clock busses. When the connection is
made,theLTC4300A-1/LTC4300A-2providebidirectional
buffering, keeping the backplane and card capacitances
isolated. Rise-time accelerator circuitry* allows the use of
weaker DC pull-up currents while still meeting rise-time
requirements. During insertion, the SDA and SCL lines are
precharged to 1V to minimize bus disturbances.
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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
Isolates Input SDA and SCL Lines from Output
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2
2
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Compatible with I C, I C Fast Mode and SMBus
Standards (Up to 400kHz Operation)
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Low I Chip Disable: <1μA (LTC4300A-1)
CC
READY Open Drain Output (LTC4300A-1)
1V Precharge on all SDA and SCL Lines
Supports Clock Stretching, Arbitration and
Synchronization
The LTC4300A-1 incorporates a CMOS threshold digital
ENABLE input pin, which forces the part into a low current
mode when driven to ground and sets normal operation
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5V to 3.3V Level Translation (LTC4300A-2)
when driven to V . It also includes an open drain READY
CC
High Impedance SDA, SCL Pins for V = 0V
CC
output pin, which indicates that the backplane and card
Small MSOP 8-Pin Package
sides are connected together. The LTC4300A-2 replaces
the ENABLE pin with a dedicated supply voltage pin, V
,
CC2
APPLICATIONS
for the card side, providing level shifting between 3.3V
and 5V systems. Both the backplane and card may be
powered with supply voltages ranging from 2.7V to 5.5V,
with no constraints on which supply voltage is higher. The
LTC4300A-2 also replaces the READY pin with a digital
CMOS input pin, ACC, which enables and disables the
rise-time accelerator currents.
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Hot Board Insertion
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Servers
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Capacitance Buffer/Bus Extender
Desktop Computer
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L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot
Swap and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are
the property of their respective owners. *Protected by U.S. Patents, including 6650174.
TheLTC4300Aisavailableinasmall8-pinMSOPpackage.
TYPICAL APPLICATION
V
Input–Output Connection tPLH
CC
3.3V
C1
0.01μF
R1
R2
R3
R4
10k
10k
10k
10k
OUTPUT
SIDE
INPUT
SIDE
150pF
SCLIN
SDAIN
SCLOUT
50pF
SDAOUT
LTC4300A-1
ENABLE READY
4300a12 TA02
GND
4300a12 TA01
4300a12fa
1