LTC4242 Linear Technology, LTC4242 Datasheet
LTC4242
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LTC4242 Summary of contents
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... OUT2 IN2 SENSE2 GATE2 PCIe PLUG-IN CONNECTOR CARD LTC4242 Dual Slot Hot Swap U ® TM 4242 Hot Swap controller allows safe board pin allows the LTC4242 to endure CC 12V OUT 3.3V OUT Normal Power-Up Sequence ENn 5V/DIV 3.3V OUT AUXOUTn 5V/DIV 12V OUTn 5V/DIV 3V ...
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... Consult LTC Marketing for parts specifi ed with wider operating temperature ranges (Note 1) 12V 12V AUXOUTn Operating Temperature Range LTC4242C ................................................ 0°C to 70°C LTC4242I ............................................. –40°C to 85°C Storage Temperature Range SSOP ................................................. –65°C to 150°C QFN .................................................... –65°C to 125°C Lead Temperature (Soldering, 10 sec) SSOP ................................................................ 300° FAULT1 36 ...
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... Fast Turn Off V = 17V, V 12VGATEn 12VOUTn V = 8.3V 3.3V 3VGATEn 3VOUTn I = 1µA (Note 3) GATE 12V Falling OUTn 3V Falling OUTn AUXOUTn Falling (Note 5) 12V OUTn 3V OUTn AUXOUTn (Note 5) LTC4242 = 3.3V 12V, unless otherwise noted. 12VINn MIN TYP MAX ● 2.7 6.0 ● 10.1 14.4 ● 3.0 6.0 ● 3.0 6.0 ● 1.6 ● 0.5 ● 0.35 ● ...
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... LTC4242 www.DataSheet4U.com ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T (Note 2) SYMBOL PARAMETER V ONn, AUXONn Pin Threshold Voltage ON(TH) ΔV ONn, AUXONn Pin Hysteresis ON(TH) V ONn, AUXONn Pin Reset Threshold Voltage ON(RTH) I ONn, AUXONn Pin Input Current ON(IN) V ENn Pin Threshold Voltage EN(TH) Δ ...
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... TEMPERATURE (°C) 4242 G04 ONn, AUXONn, ENn Low-to-High Threshold vs Temperature 1.242 1.240 1.238 1.236 1.234 1.232 100 –50 – TEMPERATURE (°C) 4242 G07 LTC4242 12V UV Rising Threshold INn vs Temperature 10.2 10.0 9.8 9.6 9.4 –50 – 100 TEMPERATURE (°C) 4242 G02 3V , AUXOUTn Power Good ...
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... LTC4242 www.DataSheet4U.com W TYPICAL PERFOR A CE CHARACTERISTICS T = 25° 3.3V AUXINn 3VINn FONn Low-to-High Threshold ( AUXINn ON 0.35 0.30 0.25 0.20 0.15 3 3.5 4 4.5 5 5.5 6 AUXINn (V) Aux Circuit Breaker Trip Current vs Temperature 650 600 550 500 450 – ...
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... G19 275 225 200 100 4242 G21 LTC4242 I Pull-Up vs Temperature GATE – 100 TEMPERATURE (°C) 4242 G20 Gate Fast Pull-Down Current vs Temperature 300 250 –50 – ...
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... LTC4242 www.DataSheet4U.com CTIO S 12V /12V : Gate Drive for 12V Supply External GATE1 GATE2 N-Channel MOSFET. An internal charge pump provides a 9µA pull-up current to ramp up 12V off, a 1mA pull-down current source discharges 12V to ground. 12V is internally clamped to 5.5V above GATEn 12V ...
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... OUTn OUTn when ENn is high, ONn is low or when V main supplies are in UVLO Device Supply Input. Operates from 2. internal undervoltage lockout circuit disables the part until the voltage at V exceeds 2.45V. CC LTC4242 CC or any of the CC 4242f 9 ...
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... LTC4242 www.DataSheet4U.com CTIO AL DIAGRA OSCILLATOR ENn ONn FONn AUXONn 12V INn 12V SENSEn 12V OUTn 3V INn 3V SENSEn 3V OUTn AUXINn 10 W CP12V CHARGE V CC CP3V PUMP CPAUX 12V IN UVLO AUXIN 10µ BOARD PRSNT – 1.235V ON1 + MAIN ON – ...
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... U OPERATIO The Functional Diagram displays the main functional ele- ments of this device. The LTC4242 is designed to control the power for two independent slots on a PCI Express backplane, allowing two boards to be safely inserted and removed. During normal operation, the charge pump sources 9µ ...
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... Si7336ADP 8mΩ Si7336ADP 13mΩ 10Ω 12V 12V 12V SENSE1 GATE1 OUT1 IN1 SENSE1 LTC4242G 12V 12V 12V SENSE2 GATE2 OUT2 IN2 SENSE2 10Ω R4 13mΩ Si7336ADP R3 Q3 8mΩ Si7336ADP Figure 1 ...
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... DELAY µF Turn-On Sequence The PCI Express power supplies are controlled by the external N-channel pass transistors, Q1 through Q4, in the 12V and 3.3V power paths, and internal pass transistors LTC4242 PULL-UP HOT PLUG CONTROL LOGIC 4242 F02 LOAD 4242 F03 ...
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... The EN pin must be pulled low to begin the start-up sequence. When these initial conditions are satisfi ed, the ON pins are checked. The LTC4242 features per slot ON pins, the AUXON and ON, to allow independent control of the main input supplies (12V and 3.3V) and the 3.3V auxiliary supplies. If the ON pin is high, the switches turn on ...
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... During an output short circuit, the surge current must be brought to a controlled level within the shortest amount of time to protect the system. The LTC4242’s active current limit enters a high current protection mode that immediately turns off the output MOSFET by pulling its gate-to-source voltage to zero ...
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... The part cannot be reset when fault overide, FON, is high. Auto-Retry After a Fault As shown in Figure 9, the LTC4242 can be confi gured to automatically retry after a fault condition by connecting both the FAULT and ON pins together with an RC network. The auto-retry circuit will attempt to restart the LTC4242 after a circuit breaker trip, as shown in the timing diagram of Figure 10 ...
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... The LTC4242 derives its power from V of 1µF should be connected between this pin and ground LOAD a lowpass fi lter shown in Figure 11 should be used. This RC network allows the LTC4242 to ride through a BD_PRST 3V /AUXIN short-circuit transient without collapsing IN below the V narrow but high glitches due to parasitic inductance. Since ...
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... To enter normal operation, pull FON and EN low and recycle the ON and AUXON pins. PCB Layout Considerations For proper operation of the LTC4242’s circuit breaker, a Kelvin connection to the sense resistors is required. The Kelvin sense PCB layout traces should be minimum length, closed together, balanced and symmetrical to minimize wiring errors ...
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... The MOSFET dissipates power during inrush charging of the output load capacitor. Assuming no load current, the MOSFET’s dissipated power equals the fi nal load capaci- = 10ms: 1 tor stored energy. Therefore, average MOSFET dissipated power is LTC4242 and Inrush Current 1(MIN) 1(MAX) 13ms 40ms ...
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... Therefore, in these events, it can be safely assumed that the MOSFETs would have minimal thermal stress on them. θ ΔT JA(MAX) If the LTC4242 operates in the diagnostic mode, user must 0.75°C/W 8.3°C ensure a safe joule heating limit of the external MOSFET. 0.6°C/W 0.3°C The internal switch will be disabled once the temperature reaches 150° ...
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... TYPICAL APPLICATIO U LTC4242 4242f 21 ...
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... LTC4242 www.DataSheet4U.com PACKAGE DESCRIPTIO 7.8 – 8.2 0.42 ±0.03 RECOMMENDED SOLDER PAD LAYOUT 5.00 – 5.60** (.197 – .221) 0.09 – 0.25 0.55 – 0.95 (.022 – .037) (.0035 – .010) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) 3. DRAWING NOT TO SCALE * DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED .152mm (.006") PER SIDE ** DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH ...
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... DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE LTC4242 3.15 ± 0.10 (2 SIDES 0.00 – 0.05 5.15 ± ...
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... FAX: (408) 434-0507 U 0.008Ω Si7336ADP 0.4Ω 10Ω 12V 12V 12V 3V 3V IN1 SENSE1 GATE1 OUT1 IN1 SENSE1 CC LTC4242G 12V 12V IN2 SENSE2 GATE2 OUT2 IN2 SENSE2 10Ω 0.008Ω 0.4Ω Si2306DS COMMENTS 6-Lead SOT-23 Package Three Selectable Circuit Breaker Thresholds Controls Supplies from 0V to – ...