LTC4240 Linear Technology, LTC4240 Datasheet

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... It also allows the user to read the status of the FAULT, RESETIN, RESETOUT, PWRGD, PRSNT1# and PRSNT2# pins. Under a fault condition, the I which of the four supplies generated the fault. The LTC4240 is available in a 28-pin narrow SSOP package ...

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... TIMER, FAULT, PWRGD, SDA, RESETOUT, LED, DRIVE, GATE, 12V OUT ....................... V EEOUT ................................................................ BE ............................................. 0.3V to (5V Operating Temperature Range LTC4240C ............................................... LTC4240I .............................................– Storage Temperature Range .................... 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL ...

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... TIMER = 0V, OFF/ PRECHARGE ADDRIN = 0V, 5V OFF/ON = 0V, TIMER = 0V TIMER = 5V, OFF/ BE –100 A BE 100 A PWRGD, RESETOUT, FAULT, SDA(I = 3mA) LED (I = 10mA 5VIN LTC4240 = 3.3V unless otherwise noted. 3VIN 5VIN MIN TYP MAX 300 600 125 250 – 50 –350 – 800 ...

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... LTC4240 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER t Stop Condition Setup Time SUSTP t Data Hold Time HDDAT t Data Setup Time SUDAT t Clock Low Period LOW t Clock High Period HIGH t Clock/Data Fall Time f t Clock/Data Rise Time r Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: All currents into device pins are positive ...

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... OUTPUT VOLTAGE (V) 4240 G11 5V PWRGD Threshold Voltage OUT vs Temperature 4.75 4.70 4.65 4.60 4.55 4.50 –50 – 100 TEMPERATURE ( C) 4240 G14 LTC4240 V Foldback Current Limit EEIN vs Temperature 0.7 0 –10V EEOUT 0.5 0.4 0 EEOUT 0.2 0.1 0 –50 – 100 TEMPERATURE ( C) 4240 G09 ...

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... LTC4240 W U TYPICAL PERFOR A CE CHARACTERISTICS 3V Input Current SENSE vs Temperature 3.3V SENSE –50 – 100 TEMPERATURE ( C) 4240 G16 Timer Pin Turn-On Current vs Temperature –10.0 OFF/ TIMER –10.5 –11.0 –11.5 –12.0 –12.5 –13.0 –50 – ...

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... Input Current OUT vs Temperature 160 3V = 3.3V OUT OFF/ 140 120 100 80 –50 – 100 TEMPERATURE ( C) 4240 G33 LTC4240 V Internal Switch Voltage Drop EEIN vs Temperature 200 I = 100mA 160 120 80 40 –50 – 100 TEMPERATURE ( C) 4240 G27 5V Foldback Current Limit Voltage ...

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... TIMER pin is above 5.5V. Once the TIMER cycle is complete, FAULT pulls low and the LTC4240 turns off (in the event of an overcurrent fault lasting longer than 35 s). The LTC4240 will remain in the off state until the OFF/ON pin is cycled high then low or power is cycled ...

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... Cycling the OFF/ON pin high and low will reset a tripped circuit breaker and start a new power-up sequence. The 2 and I C OFF/ON latch output can also be used to reset the IN electronic circuit breaker. Do not float. LTC4240 to ensure precharge IN (Pin 23): 3.3V Current Limit Sense. A sense and 3V determines the IN SENSE SENSE pin voltage exceeds 2 ...

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... LTC4240 W BLOCK DIAGRA SENSE OUT 70mV, +– + TIMER LO 165mV, A1 TIMER HI +– – + CP1 55mV +– – 4.3V UVL OFF/ON 28 FAULT 7 Q13 PWRGD 8 Q12 RESETIN 27 Q11 8V UVL Q10 + – 1. 12V 12V IN OUT 10 GATE 19 3V 12V OUT – – ...

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... U U APPLICATIO S I FOR ATIO The LTC4240 is a Hot Swap controller that allows a board to be safely inserted and removed from a CompactPCI bus slot. The LTC4240 has built-in 2-wire I interface hardware to allow software control and monitor- ing of device function and power supply status. ...

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... IN close to the pin, do not place a bypass capacitor on ADDRIN). This voltage is fed to a 5-bit A/D and compared against the address byte clocked in by the I bit A/D allows 32 unique LTC4240 devices to be connected 2 on the same I C bus. 1% resistors should be used to place the voltage at ADDRIN approximately 0.5 LSB away from each code transition ...

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... The host initiates com- munication with a START bit followed by 7 address bits. The address bits are followed by the R/W bit, which is low for Send Byte. The 9th bit is asserted low by the LTC4240 acknowledge when there has been an address match. ...

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... LTC4240 U U APPLICATIO S I FOR ATIO ADDRESS BYTE SCL START SDA 0 1 ADDR 4 ADDR 3 ADDR 2 Table 2. Command Byte Definitions HIGH C7 Don’t care C6 Don’t care C5 Ignore V faults EEOUT C4 Ignore 12V faults OUT C3 Sets RESETOUT C2 Turns OFF/ON to OFF Overrides OFF/ON pin ...

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... The long pins, which include 5V, 3.3V, V(I/O) and GND mate first. The short pins, which includes BD_SEL# (OFF/ON), mate last. At least one long 5V power pin must be connected to the LTC4240 in order for the PRECHARGE voltage to be available during Early Power. The external components connected to the precharge pin require long 3 ...

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... U APPLICATIO S I FOR ATIO stage in the hot plug sequence, indicating that the LTC4240 is in reset mode with all power switches off (BD_SEL# is still pulled high to long 5V). The 12V and –12V supplies make contact at this stage. Zener clamps Z1 and Z2 plus shunt RC snubbers R13- ...

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... A value recom- mended large value bypass capacitor is used (e.g. 100 4240 F05 power-up or during recovery from power failures. LTC4240 EEIN , current limit faults may occur during EEOUT EEOUT 4240f ...

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... TIMER pin capacitor. Current limit faults are ignored until the TIMER voltage ramps to 5.5V. This feature allows the LTC4240 to power-up CPCI boards with widely varying capacitive loads on the back end supplies. The power-up time for either of the two outputs under current ...

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... R and 55mV. If the short persists for more than SENSE 35 s, the LTC4240 latches off (Figure 8). It will stay in the latched off state until it is reset using the OFF/ON pin using the I C interface ...

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... FET will also place limitations on the maximum allowable current. 5V and 3.3V External FET Selection The LTC4240 uses external power FETs to limit and modulate the current delivered by the 3.3V and 5V sup- plies. There are several parameters to consider when selecting the FET: 1 ...

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... Transient Power Dissipation There are certain transient events that can significantly increase the power dissipated by the external FET. If the LTC4240 5V supply ( 10%) powers up into a 1.5V short (potentially manifested as a short to two diodes in series), then the FET can potentially have 4V across it with 8.8A flowing. This implies a power dissipation of 35.1W. ...

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... R8 1k MMBT2222A PRE128 10k 5% I/O PCI UP TO 128 BRIDGE I/O LINES (21154) I/O 4240 F10 LTC4240* GND PRECHARGE DRIVE 1k 4.7nF Q3 R11A R11B MMBT2222A PRECHARGE OUT R11A + R11B *ADDITIONAL DETAILS = • 1V R11A OMITTED FOR CLARITY ...

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... Figure 14. Precharge Bus Switch Application Circuit for 3.3V and Universal Hot Swap Boards W U connect the individual 10k precharge resistors to the LTC4240 1V PRECHARGE pin. The electrical connection is made (bus switches close) when the voltage on the BD_SEL# pin of the plug-in card is above 4.4V, which occurs just after the long pins have made contact. The bus ...

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... LTC4240 PRECHARGE pin for the remainder of the board extraction process. The LTC4240 BE pin can alternatively be used to drive the enable input of the bus switch. The BE signal would then keep the I/O lines precharged until all supplies reached power good status ...

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... Z3 C7 0.1 F Z3, Z4: 1PMT5.0AT3 *ADDITIONAL DETAILS OMITTED FOR CLARITY Figure 17. Place Transient Protection Device Close to the LTC4240 W U networks. Snubbers are RC networks whose time constants are large enough to damp the inductance of the parasitic resonant circuit. The snubber capacitor should be 10X to 100X the value of the plug-in board parasitic capacitance ...

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... A transient voltage suppressor with a breakdown voltage between 13.2V and 15V is advisable. The TVS should also be able to dissipate at least 150W. The SMAJ12CA can be used for both 12V and V . Place the TVS close to the LTC4240. See front EEIN page schematic. CURRENT FLOW TO LOAD ...

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... LR120601R028F 0.028 , 0.5W, 1% Resistor WSL1206R028 LR120601R011F 0.011 , 0.5W, 1% Resistor WSL2010R011 WSL2512R007 0.007 , 1W, 1% Resistor WSL2512R005 0.005 , 1W, 1% Resistor WEB SITE www.irf.com www.onsemi.com www.irctt.com www.vishay.com www.vishay.com www.diodes.com LTC4240 MANUFACTURER ON Semiconductor ON Semiconductor ON Semiconductor International Rectifier TM Vishay-Siliconix MANUFACTURER IRC-TT Vishay-Dale IRC-TT Vishay-Dale IRC-TT Vishay-Dale Vishay-Dale Vishay-Dale ...

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... LTC4240 PACKAGE DESCRIPTIO .254 MIN .0165 .0015 RECOMMENDED SOLDER PAD LAYOUT .0075 – .0098 (0.191 – 0.249) .016 – .050 (0.406 – 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" ...