LTC4305_15 Datasheet, PDF (1/20 Pages) Linear Technology – 2-Channel, 2-Wire Bus Multiplexer with Capacitance Buffering

LTC4305
2-Channel,
2-Wire Bus Multiplexer with
Capacitance Buffering
FEATURES
■ _{1:2 2-Wire Multiplexer/Switch}
■ _{Connect SDA and SCL Lines with 2-Wire Bus}
Commands
■ _{Supply Independent Bidirectional Buffer for SDA}
and SCL Lines Increases Fan-Out
■ _{Programmable Disconnect from Stuck Bus}
■ _{Compatible with I}²_{C and SMBus Standards}
■ _{Rise Time Accelerator Circuitry}
■ _{SMBus Compatible ALERT Response Protocol}
■ _{Prevents SDA and SCL Corruption During Live Board}
Insertion and Removal from Backplane
■ _{±10kV Human Body Model ESD Ruggedness}
■ _{16-Lead (4mm × 5mm) DFN and SSOP Packages}
U
APPLICATIO S
■ _{Nested Addressing}
■ _{5V/3.3V Level Translator}
■ _{Capacitance Buffer/Bus Extender}
DESCRIPTIO
The LTC^®4305 is a 2-channel, 2-wire bus multiplexer with
bus buffers to provide capacitive isolation between the
upstream bus and downstream buses. Through software
control, the LTC4305 connects the upstream 2-wire bus
to any desired combination of downstream channels.
Each channel can be pulled up to a supply voltage ranging
from 2.2V to 5.5V, independent of the LTC4305 supply
voltage. The downstream channels are also provided with
an ALERT1–ALERT2 inputs for fault reporting.
Programmable timeout circuitry disconnects the down-
stream buses if the bus is stuck low. When activated, rise
time accelerators source currents into the 2-wire bus pins
to reduce rise time. Driving the ENABLE pin low restores
all features to their default states. Three address pins
provide 27 distinct addresses.
The LTC4305 is available in 16-lead (4mm × 5mm) DFN
and SSOP packages.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Patent Pending.
TYPICAL APPLICATIO
A Level-Shifting and Nested Addressing Application
2.5V
3.3V
0.01µF
MICRO-
CONTROLLER
10k 10k 10k
V_CC
SCLIN
SCL1
SDAIN ^SDA1
ALERT ^ALERT1
LTC4305
10k 10k 10k
SFP
MODULE #1
ADDRESS = 1111 000
5V
ADR2
10k
ADR1
SCL2
ADR0
SDA2
GND
ALERT2
4305 TA01
ADDRESS = 1000 100
10k 10k
SFP
MODULE #2
ADDRESS = 1111 000
V_CC = 3.3V
SCLIN
2V/DIV
SCL1
2V/DIV
SCL2
2V/DIV
I²C Bus Waveforms
VBACK = 2.5V
VCARD1 = 3.3V
VCARD2 = 5V
500ns/DIV
4305 TA01b
4305f
1