?/DIV>
4309 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 LTC4309 provides
bidirectional buffering, keeping the backplane and card
capacitances isolated. Low offset and high V
OL
tolerance
allows cascading of multiple devices on the clock and data
busses. If SDAOUT or SCLOUT are low for 30ms, FAULT
will pull low indicating a stuck bus low condition. If DISCEN
is tied high, the LTC4309 will automatically break the bus
connection and generate up to 16 clock pulses and a stop
bit in an attempt to free the bus. A connection will resume
if the stuck bus is cleared. If DISCEN is connected to GND,
the busses will remain connected with no clock or stop
bit generation. ACC input enables rise-time accelerators
for high capacitively loaded busses.
During insertion, the SDA and SCL lines are precharged to
1V to minimize bus disturbances. When driven high, the
ENABLE input allows the LTC4309 to connect after a stop
bit or bus idle. 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.
Level Shifting Low Offset Hot
Swappable 2-Wire Bus Buffer
with Stuck Bus Recovery
n
Live Board Insertion
n
Servers
n
Capacitance Buffer/Bus Extender
n
RAID Systems
n
ATCA
n
Bidirectional Buffer Increases Fanout
n
60mV Buffer Offset Independent of Load
n
Optional Disconnect when Bus is Stuck Low
n
Prevents SDA and SCL Corruption During Live
Board Insertion and Removal from Backplane
n
Level Shift 2.5V , 3.3V and 5V Busses
n
Compatible with Non-Compliant V
OL
I
2
C Devices
n
?/SPAN>6kV Human Body Model ESD Ruggedness
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
FAULT Open Drain Output
n
1V Precharge on All SDA and SCL Lines
n
Optional Rise Time Accelerators
n
High Impedance SDA, SCL Pins for V
CC
= 0
n
Available in Small 12-Pin DFN (4mm x 3mm) and
16-Lead SSOP Packages
Rising Edge from Asserted Low
4309 TA01
ENABLE
EN
SCLIN
SDAIN
SCL1
SDA1
FAULT
ACC
V
CC
GND
SCLOUT
SDAOUT
SCL2
SDA2
LTC4309
READY
3.3V
5V
3.3V
3.3V
10k
10k    10k
2.7k    2.7k
10k
ENABLE
V
CC2
V
CC2
SCLIN
CARD
CONNECTOR
BACKPLANE
CONNECTOR
SDAIN
FAULT
ACC
V
CC
GND
SCLOUT
SDAOUT
LTC4309
READY
5V
5V
10k
100k
10k    10k
0.01糉
0.01糉
10k
FAULT
FAULT
DISCEN
DISCEN
100ns/DIV
0
0
200
400
600
800
1000
100    200
300
400
4309 G01
500    600
SDAOUT
SDAIN
LOW
OFFSET
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents including
6356140, 6650174, 7032051.