Linear Technology Corp.'s LTC4312 and LTC4314 2-wire bus multiplexers 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 1.5 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
The LTC4312 is available in 14-lead 4 x 3mm DFN and 16-lead SSOP packages, and the LTC4314 is
available in 20-lead 3 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.
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