LINEAR TECHNOLOGY - LTC4309 Data Sheet

LTC4309

Level Shifting Low Offset Hot Swappable 2-Wire Bus Buffer with Stuck Bus Recovery

FEATURES DESCRIPTION n Bidirectional Buffer Increases Fanout The LTC®4309 hot swappable 2-wire bus buffer allows n 60m V Buffer Offset Independent of Load I/O card insertion into a live backplane without corrup- n Optional Disconnect when Bus is Stuck Low tion of the data and clock busses. The LTC4309 provides n 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 VOL tolerance n Level Shift 2.5V, 3.3V and 5V Busses allows cascading of multiple devices on the clock and data n Compatible with Non-Compliant VOL I2C Devices busses. If SDAOUT or SCLOUT are low for 30ms, FAULT n ±6k V Human Body Model ESD Ruggedness will pull low indicating a stuck bus low condition. If DISCEN n Isolates Input SDA and SCL Lines from Output is tied high, the LTC4309 will automatically break the bus n Compatible with I2C™, I2C Fast-Mode and SMBus connection and generate up to 16 clock pulses and a stop n READY Open Drain Output bit in an attempt to free the bus. A connection will resume n FAULT Open Drain Output if the stuck bus is cleared. If DISCEN is connected to GND, n 1V Precharge on All SDA and SCL Lines the busses will remain connected with no clock or stop n Optional Rise Time Accelerators bit generation. ACC input enables rise-time accelerators n High Impedance SDA, SCL Pins for VCC = 0 for high capacitively loaded busses. n 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 APPLICATIONS bit or bus idle. Driving ENABLE low breaks the connection

/D IV

between SDAIN and SDAOUT, SCLIN and SCLOUT. READY

n Live Board Insertion

is an open drain output which indicates that the backplane

n Servers

and card sides are connected.

n Capacitance Buffer/Bus Extender

L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other

n RAID Systems

trademarks are the property of their respective owners. Protected by U.S. Patents including 6356140, 6650174, 7032051.

n ATCA

TYPICAL APPLICATION 3.3V

Rising Edge from Asserted Low

VCC VCC

VCC2VCC2

ENABLEEN ACC ENABLE ACC

LTC4309 LTC4309 10k 10k

LOW OFFSET SDAOUT

SCL1 SCLIN SCLOUT SCLIN SCLOUT SCL2

SDA1 SDAIN SDAOUT SDAIN SDAOUT SDA2

3.3V 5V SDAIN

10k DISCENDISCEN 10k

10k READY 10k READY

100ns/DIV

FAULT FAULT FAULT FAULT

GND GND 4309 G01

BACKPLANE CARD

4309 TA01

CONNECTOR CONNECTOR

4309fa