LTC4304 Hot Swappable 2-Wire Bus Buffer with Stuck Bus Recovery FEATURES DESCRIPTIO Automatic Disconnect of SDA/SCL Lines when Bus The LTC 4304 hot swappable 2-wire bus buffer allows I/O is Stuck Low for 30ms card insertion into a live backplane without corruption of Fault Flag for Stuck Bus the data and clock busses. When a connection is made, Recovers Stuck Busses with Automatic Clocking* the LTC4304 provides bidirectional buffering, keeping the Bidirectional Buffer* for SDA and SCL Lines backplane and card capacitances isolated. If SDAOUT or Increases Fanout SCLOUT is low for 30ms (typ), the LTC4304 automatically Prevents SDA and SCL Corruption During Live FAULT breaks the data and clock bus connection and will Board Insertion and Removal from Backplane pull low. At this time the LTC4304 automatically generates Allows Bus Pullup Voltages Above and Below V up to 16 clock pulses on SCLOUT in an attempt to free the CC 15kV Human Body Model ESD Protection bus. A connection will be enabled automatically when the Isolates Input SDA and SCL Lines from Output bus becomes free. A logic low on the ACC input enables 2 TM 2 Compatible with I C , I C Fast-Mode and SMBus the LTC4304s rise-time accelerators. A logic high on ACC Standards (Up to 400kHz Operation) disables the rise-time accelerators, which allows SDA and READY Open Drain Output SCL bus pull-up voltages below V . CC 1V Precharge on All SDA and SCL Lines During insertion, the SDA and SCL lines are precharged High Impedance SDA, SCL Pins for V = 0V CC to 1V to minimize bus disturbances. When driven high, ENABLE Gates Connection from Input to Output ENABLE allows the LTC4304 to connect after a stop bit or MSOP 10-Pin and DFN (3mm 3mm) Packages bus idle occurs. Driving ENABLE low breaks the connection U between SDAIN and SDAOUT, SCLIN and SCLOUT. READY APPLICATIO S is an open drain output that indicates when the backplane Hot Board Insertion and card sides are connected together. Servers , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Capacitance Buffer/Bus Extender All other trademarks are the property of their respective owners. Protected by U.S. Patents including 6356140, 6650174, 7032051. RAID Systems TYPICAL APPLICATIO 5V 3.3V Stuck Bus Resolved with 0.01F Automatic Clocking 10k 10k V CC 10k 10k LTC4304 SDAOUT STUCK LOW > 30ms RECOVERS SCLIN SCLOUT 5V/DIV BACK SCL CARD SCL SDAIN DISCONNECT AT TIMEOUT 5V/DIV AUTOMATIC CLOCKING SDAIN SDAOUT SCLOUT BACK SDA CARD SDA 5V/DIV FAULT READY FAULT 3.3V ENABLE ACC 5V/DIV GND 4304 TA01 100k 4304 TA01b 200 s/DIV BACKPLANE STAGGERED CARD CONNECTOR CONNECTOR 4304fa 1 U ULTC4304 (Notes 1, 2) ABSOLUTE AXI U RATI GS V to GND ..................................................0.3V to 7V SDAIN, SCLIN, SDAOUT, SCLOUT, CC SDAIN, SCLIN, SDAOUT, SCLOUT, READY, ENABLE, FAULT READY (Note 3) .........................................30mA FAULT, ACC ..................................................0.3V to 7V Storage Temperature Range Operating Temperature MSOP ................................................65C to 150C LTC4304C ................................................ 0C to 70C DFN ....................................................65C to 125C LTC4304I .............................................40C to 85C Lead Temperature (Soldering, 10sec) MSOP ...............................................................300C UUW PACKAGE/ORDER I FOR ATIO TOP VIEW ENABLE 1 10 V CC TOP VIEW SCLOUT 2 9 SDAOUT ENABLE 1 10 V CC SCLIN 3 11 8 SDAIN SCLOUT 2 9 SDAOUT 3 8 SCLIN SDAIN ACC 4 7 FAULT 4 7 ACC FAULT GND 5 6 READY 5 6 READY GND MS10 PACKAGE DD PACKAGE 10-LEAD PLASTIC MSOP 10-LEAD (3mm 3mm) PLASTIC DFN T = 125C, =200C/W JMAX JA T = 125C, = 43C/W JMAX JA EXPOSED PAD (PIN 11) PCB GND CONNECTION OPTIONAL ORDER PART NUMBER DD PART MARKING* ORDER PART NUMBER MS PART MARKING* LTC4304CDD LBBD LTC4304CMS LTBBC LTC4304IDD LBBD LTC4304IMS LTBBC Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: