LTC4309 - Level Shifting Low Offset Hot Swappable 2-Wire Bus Buffer with Stuck Bus Recovery

Features

  • Bidirectional Buffer Increases Fanout
  • 60mV Buffer Offset Independent of Load
  • Optional Disconnect when Bus is Stuck Low
  • Prevents SDA and SCL Corruption During Live Board Insertion and Removal from Backplane
  • Level Shift 2.5V, 3.3V and 5V Busses
  • Compatible with Non-Compliant VOL I²C Devices
  • ±6kV Human Body Model ESD Ruggedness
  • Isolates Input SDA and SCL Lines from Output
  • Compatible with I²C, I²C Fast-Mode and SMBus
  • READY Open Drain Output
  • FAULT Open Drain Output
  • 1V Precharge on All SDA and SCL Lines
  • Optional Rise Time Accelerators
  • High Impedance SDA, SCL Pins for VCC = 0
  • Available in Small 12-Pin DFN (4mm x 3mm) and 16-Lead SSOP Packages

Typical Application

LTC4309 Typical Application
LTC4309 Typical Application

Description

The LTC4309 hot swappable 2-wire bus buffer allows I/O card insertion into a live backplane without corruption of the data and clock busses. The LTC4309 provides bidirectional buffering, keeping the backplane and card capacitances isolated. Low offset and high VOL tolerance allows cascading of multiple devices on the clock and data busses. If SDAOUT or SCLOUT are low for 30ms, FAULT will pull low indicating a stuck bus low condition. If DISCEN is tied high, the LTC4309 will automatically break the bus connection and generate up to 16 clock pulses and a stop bit in an attempt to free the bus. A connection will resume if the stuck bus is cleared. If DISCEN is connected to GND, the busses will remain connected with no clock or stop bit generation. ACC input enables rise-time accelerators for high capacitively loaded busses.

During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances. When driven high, the ENABLE input allows the LTC4309 to connect after a stop bit or bus idle. Driving ENABLE low breaks the connection between SDAIN and SDAOUT, SCLIN and SCLOUT. READY is an open drain output which indicates that the backplane and card sides are connected.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC4309CDE#PBF 4x3 DFN-12 DE/UE C 05-08-1695 Yes
LTC4309CDE#TRPBF 4x3 DFN-12 DE/UE C 05-08-1695 Yes
LTC4309CGN#PBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LTC4309CGN#TRPBF SSOP-16 GN C 05-08-1641 (GN16) Yes
LTC4309IDE#PBF 4x3 DFN-12 DE/UE I 05-08-1695 Yes
LTC4309IDE#TRPBF 4x3 DFN-12 DE/UE I 05-08-1695 Yes
LTC4309IGN#PBF SSOP-16 GN I 05-08-1641 (GN16) Yes
LTC4309IGN#TRPBF SSOP-16 GN I 05-08-1641 (GN16) Yes


LTC4309 Package Drawing
LTC4309 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC4309CDE#PBF 4x3 DFN-12 C $3.21 $2.25 Yes
LTC4309CDE#TRPBF 4x3 DFN-12 C $2.31 Yes
LTC4309CGN#PBF SSOP-16 C $3.21 $2.25 Yes
LTC4309CGN#TRPBF SSOP-16 C $2.31 Yes
LTC4309IDE#PBF 4x3 DFN-12 I $3.86 $2.70 Yes
LTC4309IDE#TRPBF 4x3 DFN-12 I $2.76 Yes
LTC4309IGN#PBF SSOP-16 I $3.86 $2.70 Yes
LTC4309IGN#TRPBF SSOP-16 I $2.76 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

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Applications

  • Live Board Insertion
  • Servers
  • Capacitance Buffer/Bus Extender
  • RAID Systems

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Design Tools

Linear Technology provides a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more. Please visit our Design Tools page to view and download:

  • LTspice - A powerful SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators
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  • LinearLab Tools - A collection of Matlab and Python programs that provide direct access to Linear Technology’s data converter evaluation boards
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