Hot Swap 2-Wire I²C Multiplexers provide capacitive buffering.
December 20, 2010 -
Respectively multiplexing 2 and 4 channels, LTC4312 and LTC4314 provide enable pins to connect upstream I²C bus to any combination of downstream busses or cards. Both foster I²C address expansion by providing ability to address one of multiple identical devices, resolving address conflict issues. Additionally, bidirectional capacitive buffering allows extension of I²C bus size beyond 400 pF specification and prevents signal corruption during live board insertion/removal.
(Archive News Story - Products mentioned in this Archive News Story may or may not be available from the manufacturer.)
Original Press release
Linear Technology Corp.
1630 McCarthy Blvd.
Milpitas, CA, 95035
USA
2- & 4-Channel Hot Swap(TM) I2C Multiplexers Provide Capacitive Buffering Supercapacitors
MILPITAS, CA - Linear Technology Corporation introduces the LTC4312 and LTC4314 2-wire bus multiplexers, which provide individual enable pins to connect an upstream I2C bus to any combination of downstream busses or cards. The LTC4312 and LTC4314 are pin-selectable multiplexers with bus buffers that reduce component count while promoting ideal I2C signal integrity. The LTC4312 multiplexes two channels, while the LTC4314 multiplexes four channels. These devices allow easy I2C address expansion, providing the ability to address one of multiple identical devices, thus resolving address conflict issues. Bidirectional capacitive buffering allows extension of the I2C bus size well beyond the 400pF I2C bus specification and prevents I2C signal corruption during live board insertion or removal.
The LTC4312 and LTC4314 are suitable for a wide range of applications, including radial architectures in telecommunications systems such as ATCA, address expansion and level translators. Many I2C and SMBus devices operate at different supply voltage levels, yet must communicate in the same application. The LTC4312 and LTC4314 support level translation for bus voltages ranging from 1.5V to 5.5V, providing the ability to power devices from different supply voltages while maintaining fully bidirectional communications between all devices in the system. Bidirectional buffering keeps backplane and card capacitances isolated, while maintaining low offsets and high noise margins up to 0.3VCC. In addition, built-in rise time accelerators provide strong pull-up currents on SCL and SDA rising edges to meet I2C rise time specifications for heavily loaded busses; the strength of these accelerators can be selected or disabled completely. Safety measures include a stuck bus disconnect and recovery feature to disengage the input from all enabled output channels and issue clocks to the stuck device, a fault output to signal when the host a bus is stuck low, and ±4kV HBM ESD protection for increased ruggedness.
The LTC4312 is available in 14-lead 4mm x 3mm DFN and 16-lead SSOP packages, and the LTC4314 is available in 20-lead 3mm x 4mm QFN and 20-lead SSOP packages. Offered over the commercial and industrial temperature ranges, pricing for the LTC4312 and LTC4314 starts at $1.95 and $2.65 each, respectively for 1000-piece quantities. For more information, visit www.linear.com/4312 and www.linear.com/4314.
Summary of Features: LTC4312-14
1:4 Multiplexer/Switch for 2-Wire Bus (LTC4314)
1:2 Multiplexer/Switch for 2-Wire Bus (LTC4312)
Bidirectional Buffer for SDA & SCL Lines
High Noise Margin with VIL = 0.3oVCC
ENABLE Pins Connect SDA & SCL Lines
Selectable Rise Time Accelerator Current & Activation Voltage
Level Shift 1.5V, 1.8V, 2.5V, 3.3V & 5V Busses
Prevents SDA and SCL Corruption During Live Board
Stuck Bus Disconnect & Recovery
Compatible with I2C, I2C Fast Mode & SMBus
±4kV Human Body Model ESD Ruggedness
14-Lead DFN & 16-Lead MSOP Packages (LTC4312)
20-Lead SSOP & 3mm x 4mm QFN Packages (LTC4314)
About Linear Technology
Linear Technology Corporation, a member of the S&P 500, has been designing, manufacturing and marketing a broad line of high performance analog integrated circuits for major companies worldwide for three decades. The Company's products provide an essential bridge between our analog world and the digital electronics in communications, networking, industrial, automotive, computer, medical, instrumentation, consumer, and military and aerospace systems. Linear Technology produces power management, data conversion, signal conditioning, RF and interface ICs, and µModule® subsystems.
LT, LTC, LTM, µModule and are registered trademarks of Linear Technology Corp. All other trademarks are the property of their respective owners.
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