LTC4252-2 Linear Technology, LTC4252-2 Datasheet
LTC4252-2
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LTC4252-2 Summary of contents
Page 1
... An adjustable soft- start circuit controls MOSFET inrush current at start-up. The LTC4252-1/LTC4252A-1 latch off after a circuit breaker fault times out. The LTC4252-2 provides automatic retry after a fault. The LTC4252A-1/LTC4252A-2 feature tight ±1% undervoltage/overvoltage threshold accuracy. The LTC4252 is available in either an 8-pin or 10-pin MSOP ...
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... TIMER IN PWRGD SENSE 4 7 DRAIN GATE EE MS PACKAGE 10-LEAD PLASTIC MSOP = 125°C, θ 160°C/W JMAX JA MS PART MARKING LTC4252-1CMS LTWN LTC4252-2CMS LTWQ LTC4252A-1CMS LTAFX LTC4252A-2CMS LTAGE LTC4252-1IMS LTRS LTC4252-2IMS LTRT LTC4252A-1IMS LTAFY LTC4252A-2IMS LTAGF 425212fb ...
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... SENSE Pin Input Current SENSE I UV, OV Pin Input Current INP V TIMER Pin Voltage High Threshold TMRH V TIMER Pin Voltage Low Threshold TMRL LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 ● The denotes the specifications which apply over the full operating = 25°C. (Note 2) A CONDITIONS MIN ● 2mA 11 ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER I TIMER Pin Current TMR ∆I [( 50µA) – (I TMRACC TMR DRN TMR ∆I ∆I DRN DRN V DRAIN Pin Voltage Low Threshold DRNL I DRAIN Leakage Current ...
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... Analog Current Limit Voltage V vs Temperature ACL 120 115 110 105 100 105 125 –55 –35 – TEMPERATURE (°C) LTC4252-1/LTC4252 Temperature IN 2000 – 0.3V 1800 1600 1400 1200 1000 800 600 400 200 0 125 –55 –35 – ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com W TYPICAL PERFOR A CE CHARACTERISTICS V vs Temperature SS 2.40 2.35 2.30 2.25 2.20 2.15 2.10 2.05 2.00 –55 –35 – 105 125 TEMPERATURE (°C) 4252-1/2 G26 V vs Temperature OS 11.0 10.8 10.6 10.4 10.2 10.0 9.8 9.6 9.4 9.2 9.0 –55 –35 – 105 125 TEMPERATURE (°C) 4252-1/2 G29 I (ACL, Sinking) GATE vs Temperature 30 UV/ TIMER = 0V ...
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... Cycle, Sourcing) TMR vs Temperature 10 TIMER = 125 –55 –35 – TEMPERATURE (°C) LTC4252-1/LTC4252-2 UV Threshold vs Temperature 3.375 3.275 V UVH 3.175 V UV 3.075 2.975 V UVL 2.875 2.775 85 105 125 –55 –35 – TEMPERATURE (°C) ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com W TYPICAL PERFOR A CE CHARACTERISTICS I (Circuit Breaker, Sourcing) TMR vs Temperature 280 TIMER = 0µA DRN 260 240 220 200 180 –55 –35 – 105 TEMPERATURE (°C) 4252-1/2 G22 TMR DRN 10 1 0.1 0.001 0.01 0 (mA) ...
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... GATE down to regulate the MOSFET current at V circuit, SENSE may overshoot. If SENSE reaches V (200mV), the fast current limit comparator pulls GATE low with a strong pull-down. To disable the circuit breaker and ) is SS current limit functions, connect SENSE to V LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 t and t PLLUG PHLOG vs Temperature 0.8 ...
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... This cycle consists of 4 discharging ramps and 3 charging ramps. The charging and discharging currents are 5.8µA and TIMER ramps between its 1V and 4V thresholds. At the completion of a shutdown cooling cycle, the LTC4252-2 attempts a start- up cycle. – V < pull-up current of ...
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... FOR COMPONENTS, CURRENT AND VOLTAGE WITH TWO VALUES, VALUES IN PARENTHESES REFER TO THE LTC4252A. VALUES WITHOUT PARENTHESES REFER TO THE LTC4252 LTC4252A-1/LTC4252A-2 – + 2.385V V IN – – – LOGIC – + – LTC4252-1/LTC4252 6.15V 8× 1× (5V 1× 1× 58µ 58µ 2.8V + – – – + 0.5V + ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U OPERATIO Hot Circuit Insertion When circuit boards are inserted into a live backplane, the supply bypass capacitors can draw huge transient cur- rents from the power bus as they charge. The flow of current damages the connector pins and glitches the power bus, causing other boards in the system to reset ...
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... TIMER ramp is less than one circuit breaker delay time. If this condition is not met, the LTC4252-1 may shut down after one circuit breaker delay time whereas the LTC4252-2 may continue to autoretry. Board Removal If the board is withdrawn from the card cage, the UV and OV divider is the first to lose connection ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO SHUNT REGULATOR A fast responding regulator shunts the LTC4252 V Power is derived from – 48RTN by an external current limiting resistor. The shunt regulator clamps 1µF decoupling capacitor transients and contributes a short delay at start-up. R ...
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... R1 IN LTC4252A PWRGD DRAIN 10k 10 1% TIMER GATE SENSE V 34k EE 0.68µ 10nF 68nF LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A 100µF 22k Q2 C LOAD IN R5 1µF 2. IRF530S 10Ω 0.02Ω C ...
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... D C charges to 4V, the GATE pin pulls low and the LTC4252-1 T latches off while the LTC4252-2 starts a shutdown cooling (1) cycle. The LTC4252-1 remains latched off until the UV pin is momentarily pulsed low or TIMER is momentarily discharged low by an external switch or V UVLO and is then restored. The circuit breaker timeout ...
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... SHUTDOWN COOLING CYCLE For the LTC4252-1 (latchoff version), TIMER latches high with a 5.8µA pull-up after the circuit breaker fault TIMER reaches 4V. For the LTC4252-2 (automatic retry version), a shutdown cooling cycle begins if TIMER reaches the 4V threshold. TIMER starts with a 5.8µA pull-down until it reaches the 1V threshold. Then, the 5.8µ ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO and eliminates current spikes at insertion. A large external gate-source capacitor is thus unnecessary for the purpose of compensating C . Instead, a smaller value (≥ 10nF) GD capacitor C is adequate. C also provides compensation C C for the analog current limit loop. ...
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... T load capacitor to charge. That time is given by CHARGE ( The maximum current flowing in the DRAIN pin is given by: is calculated and S I DRN MAX LTC4252-1/LTC4252-2 and C . The circuit breaker should be set to accommodate MIN ( ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO Approximating a linear charging rate zero, the I component in Equation (3) can DRN(MAX) DRN be approximated with 0.5 • I DRN(MAX) tion, TIMER capacitor C is given by µ • 230 A CL CHARGE ( ) = Returning to Equation (3), the TIMER period is calculated ...
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... ACL the load current. If the SENSE voltage (V reaches the V breaker TIMER activates. The TIMER capacitor, C charged by a (230µ • I capacitor nears full charge, load current begins to decline. LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 CURRENT FLOW CURRENT FLOW FROM LOAD TO –48V BACKPLANE SENSE RESISTOR ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO V CLEARS GND – (–48RTN) – (–48V) UV/ LKO IN TIMER GATE V GATEL SS SENSE V OUT DRAIN PWRGD Figure 9. System Power-Up Timing (All Waveforms are Referenced time point 8, the load current falls and the SENSE voltage drops below V (t) ...
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... When GATE ramps past V GATEH time point 11, GATE reaches its maximum voltage as – reaches the determined by V SENSE EE LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A < 20 • V AND TIMER < TMRL , CHECK GATE < SENSE < V AND SS < 20 • V ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO Undervoltage Timing In Figure 11 when UV pin drops below V the LTC4252 shuts down with TIMER, SS and GATE all pulling low. If current has been flowing, the SENSE pin voltage decreases to zero as GATE collapses. When UV ...
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... V GATEL 20 • ACL OS 20 • • ACL V CB GATE START-UP LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A < 20 • V AND TIMER < TMRL , CHECK GATE < SENSE < V AND SS < 20 • V TMRL GATEL DRN 5.8µA 5.8µA V – V ...
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... SS pin. With this method, both the SS and TIMER pins are released at the same time (see Figure 24). Shutdown Cooling Cycle (LTC4252-2) Figure 16 shows the timer behavior of the LTC4252-2. At time point 2, TIMER exceeds V immediately and the LTC4252 shuts down. TIMER starts a shutdown cooling cycle by discharging TIMER with 5.8µ ...
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... I DRN 5.8µA TIMER GATE SS SENSE V OUT DRAIN PWRGD CB FAULT Figure 16. Shutdown Cooling Timing Behavior of LTC4252-2 (All Waveforms are Referenced SWITCH RESETS LATCHED TIMER SWITCH RELEASES 5.8µA V TMRH 230µ • I TIMER ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO Analog Current Limit and Fast Current Limit In Figure 17a, when SENSE exceeds V lated by the analog current limit amplifier loop. When SENSE drops below V , GATE is allowed to pull up. In ACL Figure 17b, when a severe fault occurs, SENSE exceeds ...
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... V SUPPLY The peak power at the fault current limit occurs at the supply overvoltage threshold. The fault current limited power is: is set Z POWER = 71V giving the same V SUPPLY LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A 230µ • I TMRH DRN 5.8µA ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com U U APPLICATIO S I FOR ATIO GND GND (SHORT PIN) R1 390k 1% R2 30.1k 1% –48V *FMMT493 Circuit Breaker with Foldback Current Limit Figure 20 shows the LTC4252A in a foldback current limit application. When V is shorted to the –48V RTN OUT supply, current flows through resistors R4 and R5. This ...
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... Q2 and Q3. Current flows into R4, Q4 and R7 and Q3 turn on. The respective node voltages at the R3 and R4 connection and the R6 and R7 connection are always kept equal to their respective sense voltages by the Q4 and Q2 V assuming the Q5 and Q8 V LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A 100µF ...
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... TIMER SENSE FDV301N GATE 560Ω DRAIN UV C IN3 2 PWRGD 1µF LTC4252-2 FDV301N 10 4 TIMER SENSE FDV301N GATE 560Ω 5 Figure 22. –48V/2.5A Diode-OR Application R IN1 3× 1.8k IN SERIES 1/4W EACH LOAD MODULE 1µ ...
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... DRAIN 0.1µ 100V 1N4003 GATE IRF530S 4 SENSE 10Ω 0.02Ω 10nF *MOC207 Figure 23. Typical Application Using a Filter Module LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A ON/OFF LUCENT JW050A1 OUT + LUCENT 0.1µF 100µF 0.1µF FLTR100V10 100V ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com PACKAGE DESCRIPTIO 5.23 (.206) MIN 0.42 ± 0.038 (.0165 ± .0015) TYP RECOMMENDED SOLDER PAD LAYOUT GAUGE PLANE 0.18 (.007) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006" ...
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... TYP 0.53 ± 0.152 (.021 ± .006) DETAIL “A” SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP LTC4252-1/LTC4252-2 0.497 ± 0.076 (.0196 ± .003 REF 3.00 ± 0.102 (.118 ± .004) (NOTE ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 www.DataSheet4U.com TYPICAL APPLICATIO GND GND (SHORT PIN) R1 402k 1% R2 32.4k 1% –48V RELATED PARTS PART NUMBER DESCRIPTION LT1640AH/LT1640AL Negative High Voltage Hot Swap Controllers in SO-8 LT1641-1/LT1641-2 Positive High Voltage Hot Swap Controllers in SO-8 LTC1642 Fault Protected Hot Swap Controller LTC4214 ...