LTC4307 - Low Offset Hot Swappable 2-Wire Bus …

1 LTC430714307fLow Offset Hot Swappable2- wire Bus Buffer with Stuck Bus RecoveryThe LTC 4307 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 LTC4307 provides bidirectional buffering, keeping the backplane and card capacitances isolated. Low Offset and high VOL tolerance allows multiple devices to be cascaded on the clock and data busses. If SDAOUT or SCLOUT are low for 30ms, the LTC4307 will automatically break the bus connection. At this time the LTC4307 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 insertion, the SDA and SCL lines are pre-charged to 1V to minimize bus disturbances.

2 When driven high, the ENABLE input allows the LTC4307 to connect after a stop bit or bus idle. Driving ENABLE low breaks the con-nection between SDAIN and SDAOUT, SCLIN and SCLOUT. READY is an open-drain output which indicates that the backplane and card sides are connected. Live Board Insertion Servers Capacitance Buffer/Bus Extender RAID Systems ATCA Bidirectional Buffer with Stuck Bus Recovery 60mV Buffer Offset Independent of Load 30ms Stuck Bus Timeout Compatible with Non-Compliant VOL I2C Devices Prevents SDA and SCL Corruption During Live Board Insertion and Removal from Backplane 5kV Human Body Model ESD Protection Isolates Input SDA and SCL Line from Output Compatible with I2 CTM, I2C Fast Mode and SMBus READY Open-Drain Output 1V Precharge on All SDA and SCL Lines High Impedance SDA, SCL Pins for VCC = 0V Small 8-Lead (3mm 3mm)

3 DFN and 8-Lead MSOP PackagesAPPLICATIO SUFEATURESDESCRIPTIOUTYPICAL F100ns/DIV00100200300400600500200mV/DIV2 0040060080010004307 TA01bSDAOUTSDAINLOWOFFSETR ising Edge from Asserted Low , LT, LTC and LTM are registered trademarks of Linear Technology other trademarks are the property of their respective by Patents, including 7032051, 6356140, 6650174 LTC430724307fVCC to GND .. to 6 VSDAIN, SCLIN, SDAOUT, SCLOUT, READY, ENABLE .. to 6 VMaximum Sink Current (SDAIN, SCLIN, SDAOUT, SCLOUT, READY) .. 50mAOperating Temperature Range LTC4307C .. 0 C to 70 C LTC4307I .. 40 C to 85 CORDER PARTNUMBERDD PART*MARKINGTJMAX = 125 C, JA = 43 C/WEXPOSED PAD (PIN 9) CONNECTION TO GND IS OPTIONALC onsult LTC Marketing for parts specifi ed with wider operating temperature ranges.

4 *The temperature grade is identifi ed by a label on the shipping (Notes 1, 7) The denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25 C. VCC = , unless otherwise noted. SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITSP ower SupplyVCCP ositive Supply Voltage CurrentVCC = , VSCLOUT = VSDAOUT = 0V (Note 6) 811 mAISDS hutdown Supply CurrentVCC = , ENABLE = GND, SDA, SCL = 9001200 AVPREP recharge VoltageSDA, SCL Floating Idle Time 5595175 sVTHR_ENABLEENABLE Input CurrentENABLE from 0V to VCC 5 AtPLH_ENENABLE Delay Off-OnVCC = (Figure 1)95 stPHL_ENENABLE Delay On-OffVCC = (Note 3) (Figure 1)10nstPLH_READY READY Delay Off-OnVCC = (Note 3) (Figure 1)10nstPHL_READYREADY Delay On-OffVCC = (Note 3) (Figure 1)

5 10nsVOL_READYREADY Output Low VoltageIPULLUP = 3mA, VCC = Off Leakage CurrentVCC = READY = 5 AELECTRICAL CHARACTERISTICSABSOLUTE AXI U RATI GSWWWUPACKAGE/ORDER I FOR ATIOUUWS torage Temperature Range DFN .. 65 C to 125 C MSOP .. 65 C to 150 CLead Temperature (Soldering, 10 sec) MSOP .. 300 CTOP VIEW9DD PACKAGE8-LEAD (3mm 3mm) PLASTIC DFN56784321 ENABLESCLOUTSCLINGNDVCCSDAOUTSDAINREADYO RDER PARTNUMBERMS8 PART*MARKINGLTC4307 CMS8 LTC4307 IMS8 LTBTVLTBTV1234 ENABLESCLOUTSCLINGND8765 VCCSDAOUTSDAINREADYTOP VIEWMS8 PACKAGE8-LEAD PLASTIC MSOPTJMAX = 125 C, JA = 200 C/WLTC430734307fSYMBOLPARAMETERCONDITION SMINTYPMAXUNITSP ropagation Delay and Rise-Time AcceleratorstPHLSDA/SCL Propagation Delay High to LowCLOAD = 50pF, to VCC on SDA, SCL, VCC = (Notes 2, 3) (Figure 1)70ns tPLHSDA/SCL Propagation Delay Low to HighCLOAD = 50pF, to VCC on SDA, SCL, VCC = (Notes 2, 3) (Figure 1)10nstRISESDA/SCL Transition Time Low to HighCLOAD = 100pF, 10k to VCC on SDA, SCL, VCC = (See Notes 3, 4) (Figure 1)

6 30300nstFALLSDA/SCL Transition Time High to LowCLOAD = 100pF, 10k to VCC on SDA, SCL, VCC = (See Notes 3, 4) (Figure 1)30300nsIPULLUPACT ransient Boosted Pull-Up CurrentPositive Transition on SDA, SCL, VCC = (Note 5) 58mAInput-Output ConnectionVOSI nput-Output Offset to VCC on SDA, SCL, VCC = , Driven SDA/SCL = 2060100mVVTHRSDA, SCL Logic Input Threshold VoltageRising , SCL Logic Input Threshold Voltage Hysteresis(Note 3)50mVCIND igital Input Capacitance SDAIN, SDAOUT, SCLIN, SCLOUT(Note 3)10pFILEAKI nput Leakage CurrentSDA, SCL, Pins 5 AVOLO utput Low VoltageSDA, SCL Pins, ISINK = 4mA, Driven SDA/SCL = , VCC = to VCC on SDA, SCL, VCC = , Driven SDA/SCL = 120160205mVVILMAXB uffer Input Logic Low VoltageVCC = Stuck Low TimeouttTIMEOUTBus Stuck Low TimerVCC = , SDAOUT, SCLOUT = 0V 253035msTiming CharacteristicsfI2C,MAXI2C Maximum Operating Frequency(Note 3)400600kHztBUFBus Free Time Between Stop and Start Condition(Note 3) stHD,STAHold Time After (Repeated) Start Condition (Note 3)100nstSU,STAR epeated Start Condition Set-Up Time(Note 3)0nstSU,STOStop Condition Set-Up Time(Note 3)0nstHD,DATIData Hold Time Input(Note 3)0nstSU,DATData Set-Up Time(Note 3)

7 100ns The denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25 C. VCC = , unless otherwise noted. ELECTRICAL CHARACTERISTICSNote 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and 2: See Propagation Delays in the Operations section for a discussion of tPHL and tPLH as a function of pull-up resistance and bus 3: Determined by design, not tested in 4: Measure points are VCC and 5: IPULLUP varies with temperature and VCC voltage as shown in the Typical Performance Characteristics 6: ICC test performed with connection circuitry 7: All currents into pins are positive.

8 All voltages are referenced to GND unless otherwise specifi , CONNECT, READY TimingtPLH_ENENABLECONNECTREADYtPLH_READ YtPHL_READYtPHL_EN4307 TD01 Rising and Falling Propagation Delay and Rise and Fall Times for SDAIN, SDAOUT and SCLIN, SCLOUTtPLHSDAIN/SCLINSDAOUT/SCLOUTtPHLtR ISEtFALLtRISEtFALL4307 TD02 Figure 1. Timing DiagramsTIMING DIAGRAMSLTC430754307fICC vs TemperatureIPULLUPAC vs TemperatureISD vs TemperatureInput-Output High to Low Propagation Delay vs COUTC onnection Circuitry VOUT VIN (VOS)TYPICAL PERFOR A CE CHARACTERISTICSUWTA = 25 C, VCC = , unless otherwise Stuck Low Timeout vs VCCTEMPERATURE ( C) 50 ICC (mA) = = = ( C) 500 IPULLUPAC (mA)4812 25025504307 G02751620100 VCC = = ( C) 50700 ISD ( A)750800850 25025504307 G0275900950100 VCC = = = ( C) 500tPHL (ns)20406080100 25025504307 G0475100 CIN = COUT = 50pFRPULLUPIN = RPULLUPOUT = 10kVCC = = = (V)2tTIMEOUT (ms) High to Low Propagation Delay vs TemperatureCOUT (pF)0tPHL (ns)

9 130120110100908070608004307 G072004006001000 CIN = 50pFRPULLUPIN = RPULLUPOUT = 10kVCC = = (k )14555 VOUT VIN (mV)65758523454307 G05678910 LTC430764307fPI FU CTIO SUUUENABLE (Pin 1): Connection Enable Input. This is a digital threshold input pin. For normal operation pull or tie ENABLE high. Driving ENABLE below isolates SDAIN from SDAOUT, SCLIN from SCLOUT and asserts READY low. A rising edge on ENABLE after a fault has occurred forces a connection between SDAIN, SDAOUT and SCLIN, SCLOUT. Connect to VCC if (Pin 2): Serial Clock Output. Connect this pin to an SCL bus segment where stuck bus recovery is needed. A pull-up resistor should be connected between this pin and VCC. SCLIN (Pin 3): Serial Clock Input. Connect this pin to an SCL bus segment that needs to be isolated from stuck bus problems.

10 A pull-up resistor should be connected between this pin and VCC. GND (Pin 4): Device Ground. Connect this pin to a ground plane for best (Pin 5): Connection READY Status Output. The READY pin is an open-drain N-channel MOSFET output that pulls low when ENABLE is low, or when the start-up and connection sequence described in the Operation section has not been completed. READY also goes low when the LTC4307 disconnects the inputs from the outputs due to the bus being stuck low for at least 30ms. READY goes high when ENABLE is high and a connection is made. Connect a pull-up resistor, typically 10k, from this pin to VCC to provide the pull-up. This pin can be fl oated if (Pin 6): Serial Data Input. Connect this pin to an SDA bus segment that needs to be isolated from stuck bus problems.