LTC4312 - Pin-Selectable, 2-Channel, 2-Wire Multiplexer with Bus Buffers


  • 1:2 Multiplexer/Switch for 2-Wire Bus
  • Bidirectional Buffer for SDA and SCL Lines
  • High Noise Margin with VIL = 0.3•VCC
  • ENABLE Pins Connect SDA and SCL Lines
  • Selectable Rise Time Accelerator Current and Activation Voltage
  • Level Shift 1.5V, 1.8V, 2.5V, 3.3V and 5V Busses
  • Prevents SDA and SCL Corruption During Live Board Insertion and Removal from Backplane
  • Stuck Bus Disconnect and Recovery
  • Compatible with I2C, I2C Fast Mode and SMBus
  • ±4kV Human Body Model (HBM) ESD Ruggedness
  • 14-Lead 4mm × 3mm DFN and 16-Lead MSOP Packages

Typical Application

LTC4312 Typical Application
LTC4312 Typical Application


The LTC4312 is a hot-swappable 2-channel 2-wire bus multiplexer that allows one upstream bus to connect to any combination of downstream busses or channels. An individual enable pin controls each connection. The LTC4312 provides bidirectional buffering, keeping the upstream bus capacitance isolated from the downstream bus capacitances. The high noise margin allows the LTC4312 to be interoperable with I2C devices that drive a high VOL (> 0.4V). The LTC4312 supports level translation between 1.5V, 1.8V, 2.5V, 3.3V and 5V busses. The hot-swappable nature of the LTC4312 allows I/O card insertion into, and removal from, a live backplane without corruption of the data and clock busses.

If both data and clock are not simultaneously high at least once in 45ms and DISCEN is high, a FAULT signal is generated indicating a stuck bus low condition, the input is disconnected from each enabled output channel and up to 16 clocks are generated on the enabled downstream busses. A three state ACC pin enables input and output side rise time accelerators of varying strengths and sets the VIL,RISING voltage.


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

Part Number Package Code Temp Package
LTC4312CDE#PBF 4x3 DFN-14 DE C 05-08-1708 RoHS
LTC4312CDE#TRPBF 4x3 DFN-14 DE C 05-08-1708 RoHS
LTC4312CMS#PBF MS-16 MS C 05-08-1669 RoHS
LTC4312CMS#TRPBF MS-16 MS C 05-08-1669 RoHS
LTC4312IDE#PBF 4x3 DFN-14 DE I 05-08-1708 RoHS
LTC4312IDE#TRPBF 4x3 DFN-14 DE I 05-08-1708 RoHS
LTC4312IMS#PBF MS-16 MS I 05-08-1669 RoHS
LTC4312IMS#TRPBF MS-16 MS I 05-08-1669 RoHS

LTC4312 Package Drawing
LTC4312 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
LTC4312CDE#PBF 4x3 DFN-14 C $2.79 $1.95 Yes
LTC4312CDE#TRPBF 4x3 DFN-14 C $2.01 Yes
LTC4312CMS#PBF MS-16 C $2.79 $1.95 Yes
LTC4312CMS#TRPBF MS-16 C $2.01 Yes
LTC4312IDE#PBF 4x3 DFN-14 I $3.20 $2.24 Yes
LTC4312IDE#TRPBF 4x3 DFN-14 I $2.30 Yes
LTC4312IMS#PBF MS-16 I $3.20 $2.24 Yes
LTC4312IMS#TRPBF MS-16 I $2.30 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.

Click here to view our complete list of demo boards


  • Telecommunications Systems Including ATCA
  • Address Expansion
  • Level Translator
  • Capacitance Buffers/Bus Extender
  • Live Board Insertion
  • PMBus

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