LTC4300A-1CMS8 Hot Swappable 2-Wire Bus Buffer for I2C and SMBus, 8-Lead MSOP

The LTC4300A-1CMS8 is a hot swappable 2-wire bus buffer in an 8-lead MSOP that protects an active I2C or SMBus backplane from the disturbance of inserting or removing a card. The input side is isolated from the output until the enable pin releases the connection, so the bus never sees the capacitance step of a card arriving.

Both SDA and SCL are buffered bidirectionally, which adds fanout and keeps the capacitance of the card's local bus away from the backplane. Clock stretching, arbitration and synchronization pass through, so multi master traffic behaves exactly as it does without the buffer in the path.

The part runs from 2.7 V to 5.5 V and handles I2C, I2C Fast Mode and SMBus traffic up to 400 kHz. With the buffer disabled the supply current drops, which matters on line cards that hold the bus off while a controller boots.

When VCC is 0 V the SDA and SCL pins present high impedance, so a card that is unpowered or in reset does not load the backplane. The MSOP package keeps the footprint small, and the C grade is specified from 0 C to 70 C.

Every order ships as new stock with full traceability, RoHS compliant and lead free, and samples plus volume pricing are available on request.

• Bidirectional buffer for SDA and SCL lines
• Increases bus fanout and isolates line capacitance
• Prevents SDA and SCL corruption during live board insertion and removal
• Isolates input SDA and SCL lines from the output
• Connection enable pin gates the input to output path
• Low supply current when the buffer is disabled
• Supports clock stretching, arbitration and synchronization
• Compatible with I2C, I2C Fast Mode and SMBus up to 400 kHz
• High impedance SDA and SCL pins when VCC = 0 V
• Small 8-pin MSOP package

• Live board insertion and removal in rack systems
• Hot swap line cards and backplane I2C buses
• Servers, telecom and networking equipment
• Bus capacitance isolation and fanout expansion
• Redundant or isolated system management buses
• Industrial control, test and instrumentation boards

The LTC4300A-1CMS8 is the standard choice for isolating a hot swapped I2C or SMBus card from an active backplane in commercial temperature equipment.

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We also carry the related parts shown below, so mixed bills of material can ship together from a single supplier.