LTC4308 Datasheet, PDF (1/16 Pages) Linear Technology – Low Voltage, Level Shifting Hot Swappable 2-Wire Bus Buffer with Stuck Bus Recovery

LTC4308
Low Voltage, Level Shifting
Hot Swappable 2-Wire Bus
Buffer with Stuck Bus Recovery
FEATURES
DESCRIPTION
n _{Optimized for Low Voltage Systems Down to 0.9V}
n _{Bidirectional Buffer with Stuck Bus Recovery}
n _{–200mV Offset In-Out/+300mV Offset Out-In}
n _{30ms Stuck Bus Timeout}
n _{Compatible with Non-Compliant VOL I}²_{C Devices}
n _{Prevents SDA and SCL Corruption During Live}
Board Insertion and Removal from Backplane
n _{±6kV Human Body Model (HBM) ESD Protection}
n _{Isolates Input SDA and SCL Lines from Output}
n _{Compatible with I}²_{C™, I}²_{C Fast Mode and SMBus}
n _{READY Open-Drain Output}
n _{1V Precharge on SDAOUT and SCLOUT Lines}
n _{Small 8-Lead (3mm × 3mm × 0.75mm) DFN and}
8-Lead MSOP Packages
APPLICATIONS
n _{Live Board Insertion}
n _Servers
n _{Capacitance Buffer/Bus Extender}
n _{RAID Systems}
n _ATCA
The LTC^®4308 hot swappable, 2-wire bus buffer allows
I/O card insertion into a live backplane without corrup-
tion of the data and clock busses. The LTC4308 provides
bidirectional buffering, keeping the backplane and card
capacitances isolated. Negative offset from output to
input allows communication between output bus devices
with high V_OL and devices on the low voltage input side,
where bus supplies can be as low as 0.9V. If SDAOUT or
SCLOUT are low for 30ms, the LTC4308 will automati-
cally break the Input-Output connection. At this time the
LTC4308 automatically generates up to 16 clock pulses
on SCLOUT in an attempt to free the bus. A connection
will resume if the stuck bus is cleared.
During insertion, the SDAOUT and SCLOUT lines are pre-
charged to 1V to minimize bus disturbances. When driven
high, the ENABLE input allows the LTC4308 to connect after
a stop bit or bus idle condition. 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.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Hot Swap
is a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners. Protected by U.S. Patents including 7032051, 6650174, 6356140.
TYPICAL APPLICATION
The LTC4308 in a 1.2V
Microcontroller Application
1.2V
5V
0.01μF
MICRO-
CONTROLLER
2.7k 2.7k
V_CC
LTC4308
SCLIN SCLOUT
SDAIN SDAOUT
ENABLE
READY
GND
10k 2.7k 2.7k
READY
CARD_SCL
CARD_SDA
4308 TA01a
2V/DIV
CH1
1.2V to 5V Level Shifting
SDAOUT
0.5V/DIV
CH2
SDAIN
1μs/DIV
4308 TA01b
4308f
1