Document
FEATURES
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 www.DataSheet4U.com s Compatible with I2CTM Standard Mode, I2C 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
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LTC4302-1/LTC4302-2 Addressable 2-Wire Bus Buffers DESCRIPTIO
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 maintain electrical isolation between the backplane and peripheral board until their VCC 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 possible addresses set by an external resistive divider between VCC 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 VCC is low. Rise time accelerator circuitry* allows for heavier capacitive bus loading while still meeting system timing requirements. 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 outputs or push-pull outputs. The LTC4302-2 option replaces one GPIO pin with a second supply voltage pin VCC2, providing level shifting between systems with different supply voltages. The LTC4302-1/LTC4302-2 are available in a 10-pin MSOP package.
U APPLICATIO S
s s s s s
Live Board Insertion 5V/3.3V Level Translator Servers Capacitance Buffer/Bus Extender 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
TYPICAL APPLICATIO
2.7V to 5.5V
R3 10k
R4 10k
R1 1870Ω
R2 2000Ω
C1 0.01µF VCC LTC4302-1 SDA CARD SDA SDAIN SDAOUT SCL CARD SCL SCLOUT SCLIN CONN ADDRESS GPIO2 GPIO1 R5 10k GND
R6 10k
R7 10k
R8 1k
R9 1k
OUTPUT SIDE 50pF
LED LED
4203 TA01a
U
U
Input-Output Connection tPLH
INPUT SIDE 150pF 0.1µs/DIV
4032 F10
sn430212 430212fs
1
LTC4302-1/LTC4302-2
ABSOLUTE AXI U RATI GS
VCC to GND ................................................. –0.3V to 7V SDAIN, SCLIN, SDAOUT, SCLOUT, GPIO1, CONN, GPIO2 (LTC4302-1), VCC2 (LTC4302-2) ........................................ –0.3V to 7V ADDRESS ....................................... –0.3V to VCC + 0.3V
U U W PACKAGE/ORDER I FOR ATIO
www.DataSheet4U.com
TOP VIEW SDAIN SCLIN CONN ADDRESS GND 1 2 3 4 5 10 9 8 7 6 SDAOUT SCLOUT VCC GPIO2 GPIO1
ORDER PART NUMBER LTC4302C.