LTC4244 LINER [Linear Technology], LTC4244 Datasheet

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... After the power-up cycle is complete, the TIMER pin capacitor serves as auxiliary V LTC4244-1 to function without interruption in the pres- ence of voltage spikes on the 12V output indicates when all four supplies are within toler- ance. The OFF/ON pin is used to cycle board power or reset the circuit breaker ...

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... PRECHARGE, GATE ....................................... 20mA V ................................................ –14.4V to 0.3V EEOUT TIMER, 12V OUT ........................................... Operation Temperature Range LTC4244C/LTC4244C-1 ........................... LTC4244I/LTC4244I-1 ........................ – Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T otherwise noted. SYMBOL PARAMETER ...

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... TIMER = 0V EEIN EEOUT Junction Temperature, Ramping Up 12V , Ramping Down OUT 5V , Ramping Down OUT 3.3V , Ramping Down OUT V , Ramping Up, LTC4244 Only EEOUT OFF/ON, RESETIN, FAULT OFF/ON, RESETIN, FAULT OFF/ON, RESETIN = 0V OFF/ON, RESETIN = 12V RESETOUT, FAULT = 5V, OFF/ON = 0V, RESETIN = 3.3V PWRGD = 5V, OFF/ 5V SENSE OUT 3. ...

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... LTC4244/LTC4244 TYPICAL PERFOR A CE CHARACTERISTICS 3.3V and 5V Current Foldback Profile VOLTAGE (V) 4244 G01 12V Foldback Current Limit vs Temperature 0.9 12V = 10V 0.8 OUT 0.7 0.6 12V = 0V 0.5 OUT 0.4 0.3 0.2 0.1 0 –50 – 100 TEMPERATURE ( C) 4244 G04 V Internal Switch Voltage Drop ...

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... TEMPERATURE ( C) 4244 G14 12V Powergood Threshold OUT Voltage vs Temperature 11.090 11.085 11.080 11.075 11.070 11.065 11.060 11.055 –50 – 100 TEMPERATURE ( C) 4244 G17 LTC4244/LTC4244-1 12V Supply Current vs IN Temperature 3.94 3.93 3.92 3.91 3.90 3.89 3.88 3.87 –50 – 100 TEMPERATURE ( C) 4244 G12 5V Undervoltage Lockout vs ...

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... LTC4244/LTC4244 TYPICAL PERFOR A CE CHARACTERISTICS 5V Powergood Threshold OUT Voltage vs Temperature 4.603 4.602 4.601 4.600 4.599 4.598 4.597 4.596 4.595 4.594 –50 – 100 TEMPERATURE ( C) 4244 G19 Gate Pin Fault Current vs Temperature 16 FAULT = –50 –25 ...

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... Once the TIMER cycle is complete, FAULT will IN pull low and the LTC4244 latches off in the event of an overcurrent fault. The part will remain in the latched off state until the OFF/ON pin is cycled high then low. Forcing the FAULT pin low with an external pull-down will cause ...

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... LTC4244/LTC4244 CTIO S RESETOUT (Pin 10): Open-Drain Digital Output. Connect the CPCI_LOCAL_RST# signal to the RESETOUT pin. RESETOUT is the logical combination of the RESETIN and PWRGD. DRIVE (Pin 11): Precharge Base Drive Output. Provides base drive for an external NPN emitter-follower that in turn biases the PRECHARGE node. ...

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... Supply Output EEOUT connected between V than –11.1V before the PWRGD pin pulls low. The V pin to the power good comparator is disabled for the LTC4244- 390 active pull-up discharges V the power switches are turned off. 12V (Pin 20): 12V Supply Output. A 0.5 switch is ...

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... LTC4244/LTC4244-1 W BLOCK DIAGRA 3. 3.3V SENSE 16 GATE 15 5V SENSE – + – 5V CURRENT 50mV FAULT + + + – – TIMER_LO 50mV TIMER_HI 150mV 8 s UVL RISING MONITOR EDGE V EEIN DELAY REF UVL FALLING RESET EDGE DELAY OFF/ON 5 PWRGD 7 RESETOUT 10 RESETIN 9 CP_OFF ...

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... W U • Current limit during power up: the supplies are allowed to power up in current limit. This allows the LTC4244 to power up boards with widely varying capacitive loads without tripping the circuit breaker. The maximum allowable power-up time is adjustable using the TIMER pin capacitor. • ...

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... CPCI Connector Pin Sequence The staggered lengths of the CPCI male connector pins ensure that all power supplies are physically connected to the LTC4244 before back-end power is allowed to ramp up (BD_SEL# asserted low). The long pins, which include 5V, 3.3.V, V(I/O) and GND, mate first. The short BD_SEL# pin mates last ...

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... HEALTHY# signal pulls high and LOCAL_PCI_RST# will be asserted low. TIMER 10V/DIV GATE 10V/DIV 12V 10V/DIV 5V 10V/DIV 3.3V 10V/DIV V EEOUT 10V/DIV BD_SEL# 10V/DIV HEALTHY# 10V/DIV LCL_PCI_RST# 10V/DIV 4244 F02 LTC4244/LTC4244-1 OUT OUT OUT 20ms/DIV Figure 3. Normal Power-Down Sequence 4244 F03 42441f 13 ...

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... In the event of a short-circuit or overcurrent condition, the V ) LTC4244’s GATE pin can be pulled down within 2 s since a 1k (R5 in Figure 1) decouples C1 from the gates of the external MOSFET’s (Q1 and Q2 in Figure 1). TIMER Pin Capacitor Selection During a power-up sequence current source is connected to the TIMER pin and current limit faults are ignored until the voltage ramps to within 1 ...

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... If either the 12V or –12V supply exceeds current limit after power-up, the shorted supply’s current will drop 12V OUT 10V/DIV 5V OUT 10V/DIV V EEOUT 10V/DIV 20ms/DIV Figure 4. Power-Up Into a Short on a 3.3V Output LTC4244/LTC4244-1 4244 F04 15 42441f ...

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... The LTC4244 will stay in the latched off state until the OFF/ON pin is cycled high then low or the 12V power supply is cycled low then high. ...

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... The PRECHARGE input and DRIVE output pins are in- tended for use in generating the 1V precharge voltage that is used to bias the bus I/O connector pins during board insertion and extraction. The LTC4244 is also capable of generating precharge voltages other than 1V. Figure 7 shows a circuit that can be used in applications requiring a precharge voltage of less than 1V ...

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... R14 10 5% LTC4244* PRECHARGE DRIVE 4.7nF R10A R10B 5% Q3 PRECHARGE OUT MMBT2222A R10A + R10B V = • 1V PRECHARGE R10A LTC4244* PRECHARGE DRIVE R10 C3 4.7nF MMBT2222A 12 5% PRECHARGE OUT 10% BUS SWITCH 55mA OUT ...

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... Figure 11 allows the LTC4244 to be reset simply by pressing a pushbutton switch on the CPCI plug in board. This arrangement eliminates the requirement to extract and reinsert the CPCI board in order to reset the LTC4244’s circuit breaker. BACKPLANE CONNECTOR ...

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... Each medium or long power pin connected to the CPCI female connector on the plug-in board is required to have a 10nF ceramic bypass capacitor to ground. Bulk capacitors are only allowed on the switched output side of the LTC4244 (5V , 3.3V OUT tance is allowed on the 5V ...

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... LTC4244 in the event of abrupt changes in supply current. All protection networks should be mounted very close to the LTC4244’s supply pins using short lead lengths to minimize trace resistance and induc- tance. This is shown schematically in Figures 12 and 13 ...

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... MOSFETs should include good thermal management techniques for optimal device power dissipation. A recommended PCB layout for the sense resistor, the power MOSFET and the GATE drive compo- nents around the LTC4244 is illustrated in Figure 15. In Hot CURRENT FLOW TO LOAD 3.3V ...

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... TRIP according to Equation 2 is TRIP(MAX) ON 11.5A 8. order to guarantee that the LTC4244’s TIMER fault inhibit period is greater than 24ms, the value of C should be: C TIMER C TIMER So a value of 82nF ( 10%) should suffice. LTC4244/LTC4244-1 ON < 6A – – ...

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... The amount of heating in the 5V and 3.3V MOSFETs during a normal power cycle depends on the LTC4244’s GATE pin current (refer to Gate Current vs Temperature plot in the Typical Performance Characteristics section). The magni- tude of the off-on power pulse that results in maximum ...

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... Power MOSFET and Sense Resistor Selection Tables 7 and 8 list current sense resistors and power MOSFET transistors, respectively, that can be used with the LTC4244’s circuit breakers. Table 9 lists supplier web site addresses for discrete components mentioned throughout the LTC4244 data sheet. ...

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... LTC4244/LTC4244 APPLICATIO S I FOR ATIO Table 7. Sense Resistor Selection Guide CURRENT LIMIT VALUE PART NUMBER 1A LR120601R055F WSL1206R055 2A LR120601R028F WSL1206R028 5A LR120601R011F WSL2010R011 7.6A WSL2512R007 10A WSL2512R005 Table 8. N-Channel Power MOSFET Selection Guide CURRENT LIMIT VALUE PART NUMBER MMDF3N02HD MMSF5N02HD 5A to 10A ...

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... BSC 1 .015 .004 45 .0532 – .0688 (0.38 0.10) (1.35 – 1.75) 0 – 8 TYP .008 – .012 (0.203 – 0.305) TYP LTC4244/LTC4244-1 .337 – .344* (8.560 – 8.738) .058 (1.473 REF .150 – .157** (3.810 – 3.988) ...

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... R14 • 10 • Z3, Z4: SMAJ5.0A Figure 17. Typical LTC4244-1 Application COMMENTS Dual Supplies from 3V to 12V, Additional –12V Single Supply Hot Swap in SO-8 from 3V to 12V Negative High Voltage Supplies from –10V to –80V Supplies from 9V to 80V, Latch Off/Autoretry 3V to 15V, Overvoltage Protection Up to 33V 3.3V, 5V, 12V, – ...