LTC4301CDD Supply Independent Hot Swappable 2-Wire Bus Buffer, 8-Lead DFN 3x3

The LTC4301CDD is a supply independent hot swappable 2-wire bus buffer in an 8-lead 3 mm x 3 mm DFN package. Because the bus pull-up voltage may sit above or below VCC, the part drops into mixed 2.5 V, 3.3 V and 5 V backplanes without an extra level shifting stage.

Both lines are buffered bidirectionally, so the device adds fanout and keeps the capacitance of the card isolated from the backplane. The CS pin gates the connection from input to output, which lets the host bring a newly inserted card onto the bus in a controlled order instead of at the instant of contact.

Every SDA and SCL line carries a 1 V precharge, so connector pins settle to a defined level before contact is fully made. Each pin is rated to 10 kV human body model ESD, and SDA and SCL go high impedance when VCC is 0 V, so an unpowered card does not load a live bus.

Clock stretching, arbitration and synchronization pass through unchanged, and the part meets I2C, I2C Fast Mode and SMBus timing up to 400 kHz. The 3 mm x 3 mm DFN with exposed pad keeps the footprint small on dense line cards, 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.

• Supply independent operation, pull-ups may be above or below VCC
• Bidirectional buffer for SDA and SCL lines
• Increases bus fanout and isolates line capacitance
• Prevents SDA and SCL corruption during live insertion and removal
• Isolates input SDA and SCL lines from the output
• 10 kV human body model ESD protection on all pins
• 1 V precharge on all SDA and SCL lines
• Supports clock stretching, arbitration and synchronization
• High impedance SDA and SCL pins when VCC = 0 V
• CS pin gates the connection from input to output
• Compatible with I2C, I2C Fast Mode and SMBus up to 400 kHz
• 8-lead 3 mm x 3 mm DFN package with exposed pad

• 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 LTC4301CDD suits line cards that are inserted into a live backplane and must not disturb an active I2C or SMBus segment while the connector is mating.

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