LTC4302-1_15 Datasheet, PDF (1/20 Pages) Linear Technology – Addressable 2-Wire Bus Buffers

LTC4302-1/LTC4302-2
Addressable
2-Wire Bus Buffers
FEATURES
DESCRIPTIO
s _{Bidirectional Buffer for SDA and SCL Lines}
Increases Fanout
s _{Connect SDA and SCL Lines with 2-Wire Bus}
Commands
s _{Prevents SDA and SCL Corruption During Live Board}
Insertion and Removal from Backplane
s _{Compatible with I}²_C^TM _{Standard Mode, I}²_{C Fast}
Mode and SMBus Standards
s _{Rise Time Accelerators on SDA, SCL Lines}
s _{1V Precharge on SDA and SCL Lines}
s _{32 Unique Addresses from a Single ADDRESS Pin}
s _{Two General Purpose Inputs-Outputs (LTC4302-1)}
s _{Translates Between 5V and 3.3V Systems}
(LTC4302-2)
s _{Small 10-Pin MSOP Package}
U
APPLICATIO S
s _{Live Board Insertion}
s _{5V/3.3V Level Translator}
s _Servers
s _{Capacitance Buffer/Bus Extender}
s _{Nested Addressing}
, LTC and LT are registered trademarks of Linear Technology Corporation.
I²C is a trademark of Philips Electronics N.V.
*U.S. Patent No. 6,650,174
The LTC^®4302-1/LTC4302-2 addressable I²C bus and
SMBus compatible bus buffers allow a peripheral board
to be inserted and removed from a live backplane without
corruption of the bus. The LTC4302-1/LTC4302-2 main-
tain electrical isolation between the backplane and periph-
eral board until their V_CC supply is valid and a master
device on the backplane side addresses the LTC4302-1/
LTC4302-2 and commands them to connect. The
LTC4302-1/LTC4302-2’s ADDRESS pin provides 32 pos-
sible addresses set by an external resistive divider be-
tween V_CC and GND. The LTC4302-1/LTC4302-2 work
with supply voltages ranging from 2.7V to 5.5V. The SDA
and SCL inputs and outputs do not load the bus lines when
V_CC is low.
Rise time accelerator circuitry* allows for heavier capaci-
tive bus loading while still meeting system timing require-
ments. During insertion, the SDA and SCL lines are
precharged to 1V to minimize bus disturbances. Two
general purpose input/output pins (GPIOs) on the
LTC4302-1 can be configured as inputs, open-drain out-
puts or push-pull outputs. The LTC4302-2 option replaces
one GPIO pin with a second supply voltage pin V_CC2,
providing level shifting between systems with different
supply voltages. The LTC4302-1/LTC4302-2 are available
in a 10-pin MSOP package.
TYPICAL APPLICATIO
2.7V
to
5.5V
R3 R4 R1
R5
10k 10k 1870Ω 10k
V_CC
C1
0.01µF R6 R7 R8
R9
10k 10k 1k
1k
SDA
LTC4302-1
CARD SDA
SCL ^SDAIN
SCLIN
SDAOUT
SCLOUT ^{CARD SCL}
R2
2000Ω
CONN
ADDRESS GPIO2
GPIO1
GND
LED
LED
4203 TA01a
Input-Output Connection t_PLH
OUTPUT
SIDE
50pF
INPUT
SIDE
150pF
0.1µs/DIV
4032 F10
sn430212 430212fs
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