LTC4309
Level Shifting Low Offset Hot
Swappable 2-Wire Bus Buffer
with Stuck Bus Recovery
FEATURES DESCRIPTION
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Bidirectional Buffer Increases Fanout The LTC 4309 hot swappable 2-wire bus buffer allows
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60mV Buffer Offset Independent of Load I/O card insertion into a live backplane without corrup-
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Optional Disconnect when Bus is Stuck Low tion of the data and clock busses. The LTC4309 provides
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Prevents SDA and SCL Corruption During Live bidirectional buffering, keeping the backplane and card
Board Insertion and Removal from Backplane capacitances isolated. Low offset and high V tolerance
OL
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Level Shift 2.5V, 3.3V and 5V Busses allows cascading of multiple devices on the clock and data
2
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Compatible with Non-Compliant V I C Devices busses. If SDAOUT or SCLOUT are low for 30ms, FAULT
OL
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6kV Human Body Model ESD Ruggedness will pull low indicating a stuck bus low condition. If DISCEN
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Isolates Input SDA and SCL Lines from Output is tied high, the LTC4309 will automatically break the bus
2 2
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Compatible with I C, I C Fast-Mode and SMBus connection and generate up to 16 clock pulses and a stop
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READY Open Drain Output bit in an attempt to free the bus. A connection will resume
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FAULT Open Drain Output if the stuck bus is cleared. If DISCEN is connected to GND,
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1V Precharge on All SDA and SCL Lines the busses will remain connected with no clock or stop
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Optional Rise Time Accelerators bit generation. ACC input enables rise-time accelerators
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High Impedance SDA, SCL Pins for V = 0 for high capacitively loaded busses.
CC
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Available in Small 12-Pin DFN (4mm x 3mm) and
During insertion, the SDA and SCL lines are precharged to
16-Lead SSOP Packages
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
APPLICATIONS
between SDAIN and SDAOUT, SCLIN and SCLOUT. READY
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Live Board Insertion
is an open drain output which indicates that the backplane
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Servers
and card sides are connected.
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Capacitance Buffer/Bus Extender
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
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RAID Systems
trademarks are the property of their respective owners. Protected by U.S. Patents including
6356140, 6650174, 7032051.
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ATCA
TYPICAL APPLICATION
3.3V
Rising Edge from Asserted Low
5V
0.01 F
1000
10k 10k
0.01 F
V V
CC CC
V V
CC2 CC2
800
EN ENABLE ACC ENABLE ACC
2.7k 2.7k
100k
LTC4309 LTC4309
10k 10k 600
LOW
OFFSET SDAOUT
SCL1 SCLIN SCLOUT SCLIN SCLOUT SCL2
400
SDA2
SDA1 SDAIN SDAOUT SDAIN SDAOUT
SDAIN
3.3V 5V
3.3V 200
5V
DISCEN 10k DISCEN 10k
0
READY 10k READY
10k
0 100 200 300 400 500 600
100ns/DIV
FAULT FAULT FAULT FAULT
4309 G01
GND GND
BACKPLANE CARD
4309 TA01
CONNECTOR CONNECTOR
4309fa
1
200mV/DIVLTC4309
ABSOLUTE MAXIMUM RATINGS
(Note 1, 6)
V , V to GND ............................................0.3 to 6V Operating Temperature
CC CC2
SDAIN, SCLIN, SDAOUT, SCLOUT, READY, LTC4309C ................................................ 0C to 70C
ENABLE, FAULT, ACC, DISCEN .......................0.3 to 6V LTC4309I.............................................. 40C to 85C
Maximum Sink Current (SDA, SCL, FAULT, READY) Storage Temperature Range (DE)........... 65C to 125C
I ......................................................................50mA Storage Temperature Range (GN) .......... 65C to 150C
SINK
Lead Temperature (Soldering, 10 sec)
GN Package ......................................................300C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
1
ENABLE 16 V
CC
ENABLE 1 12 V
CC
2
NC 15 NC
DISCEN 2 11 V
CC2
3
DISCEN 14 V
CC2
SCLOUT 3 10 SDAOUT
4
SCLOUT 13 SDAOUT
13
SCLIN 4 9 SDAIN
SCLIN 5
12 SDAIN
8 FAULT
ACC 5
ACC 6
11 FAULT
GND 6 7 READY
NC 7
10 NC
GND 8
9 READY
DE12 PACKAGE
12-LEAD (4mm 3mm) PLASTIC DFN
GN PACKAGE
T = 125C, = 43C/W
JMAX JA
16-LEAD NARROW PLASTIC SSOP
EXPOSED PAD (PIN 13) PCB CONNECTION TO GND IS OPTIONAL
T = 150C, = 110C/W
JMAX JA
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC4309CDE#PBF LTC4309CDE#TRPBF 4309 12-Lead (4mm 3mm) Plastic DFN 0C to 70C
LTC4309IDE#PBF LTC4309IDE#TRPBF 4309 12-Lead (4mm 3mm) Plastic DFN 40C to 85C
LTC4309CGN#PBF LTC4309CGN#TRPBF 4309 16-Lead Plastic SSOP 0C to 70C
LTC4309IGN#PBF LTC4309IGN#TRPBF 4309I 16-Lead Plastic SSOP 40C to 85C
Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based nish parts.
For more information on lead free part marking, go to: