LTC4252-1IMS8#TRPBF Linear Technology, LTC4252-1IMS8#TRPBF Datasheet
LTC4252-1IMS8#TRPBF
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LTC4252-1IMS8#TRPBF Summary of contents
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... 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 . L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners ...
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... PLASTIC MSOP = 125°C, θ 160°C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LTC4252-1CMS8 LTC4252-1CMS8#TRPBF LTC4252-2CMS8 LTC4252-2CMS8#TRPBF LTC4252-1IMS8 LTC4252-1IMS8#TRPBF LTC4252-2IMS8 LTC4252-2IMS8#TRPBF LEAD BASED FINISH TAPE AND REEL LTC4252-1CMS LTC4252-1CMS#TR LTC4252-2CMS LTC4252-2CMS#TR LTC4252A-1CMS LTC4252A-1CMS#TR LTC4252A-2CMS LTC4252A-2CMS#TR LTC4252-1IMS LTC4252-1IMS#TR ...
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... Low-to-High Transition ● ( ● for LTC4252A Only) ● 5.85 ● 5.25 Low-to-High Transition ● ● ( ● for LTC4252A Only) ● 4V 50mV SENSE ● LTC4252-1/-2 LTC4252A-1/-2 TYP MAX MIN TYP MAX 13 14.5 11.5 13 14.5 ...
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... DRN TMR Timer Off (Circuit Breaker/ Shutdown Cooling, Sinking TMR = Timer On (Circuit Breaker with DRN I = 50μA) DRN For PWRGD Status (MS Only (4V for LTC4252A) DRAIN I = 50μA DRN I = 1.6mA (MS Only 5mA (MS Only (Sourcing) (MS Only) PWRGD SS Pin Floating, V Ramps from SS ...
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... TEMPERATURE (°C) Analog Current Limit Voltage V vs Temperature ACL 120 115 110 105 100 125 –55 –35 – 105 25 65 TEMPERATURE (°C) LTC4252-1/LTC4252 Temperature IN 2000 – 0.3V 1800 1600 1400 1200 1000 800 600 400 200 0 125 –55 –35 –15 5 ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 TYPICAL PERFORMANCE 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) 425212 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 –15 ...
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... TEMPERATURE (°C) I (Initial Cycle, Sourcing) TMR vs Temperature 10 TIMER = 125 –55 –35 – 105 25 65 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 2.775 125 –55 –35 – TEMPERATURE (°C) 425212 G14 – SENSE ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 TYPICAL PERFORMANCE CHARACTERISTICS I (Circuit Breaker, Sourcing) TMR vs Temperature 280 TIMER = 0μA DRN 260 240 220 200 180 –55 –35 – 105 TEMPERATURE (°C) 425212 G22 TMR DRN 10 1 0.1 0.001 0.01 0 (mA) DRN 425212 G33 V vs Temperature DRNL 2.60 FOR PWRGD STATUS (MS ONLY) 2 ...
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... SS pin voltage to 2.2V (50k resistor and 1.4V IN for the LTC4252A). This corresponds to an analog current limit SENSE voltage of 100mV (60mV for the LTC4252A). If the SS capacitor is omitted, the SS pin ramps up in about 180μs. The SS pin is pulled low under any of the following ...
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... V quickly pulls low and GATE is activated. If SENSE exceeds 50mV while GATE is high, a circuit breaker cycle begins with a 230μA pull-up current charging DRAIN is approximately 7V (6V for LTC4252A) dur- T ing this cycle, the timer pull-up has an additional current of 8 • I DRN reaches 4V, a 5.8μ ...
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... EE (2.5k *OV AND UV ARE TIED TOGETHER ON THE MS8 PACKAGE. OV AND UV ARE SEPARATE PINS ON THE MS PACKAGE ** ONLY AVAILABLE IN THE MS PACKAGE 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 58μ ...
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... MOSFET switch (see Figure 1). Both inrush control and short-circuit protection are provided by the MOSFET. A detailed schematic for the LTC4252A is shown in Figure 2. – 48V and –48RTN receive power through the longest con- nector pins and are the first to connect when the board is inserted ...
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... Above 1.2V, TIMER ramps up important to set the timer delay so that, regardless of which start-up mode is used, the 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. ...
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... The LTC4252 is fundamentally a low voltage device that operates with –48V as its reference ground. To further protect against arc discharge into its pins, the area in and around the LTC4252 and all associated components should be free of any other planes such as chasis ground, return, or secondary-side power and ground planes. ...
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... The R1-R2 divider values shown in the Typical Application set a standing current of slightly more than 100μA and define an impedance at UV/OV of 30kΩ. In most applica- tions, 30kΩ impedance coupled with 300mV UV hysteresis makes the LTC4252 insensitive to noise. If more noise immunity is desired, add a 1nF to 10nF filter capacitor from UV/ ...
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... Intermittent overloads may exceed the 50mV threshold at SENSE, but, if their duration is sufficiently short, TIMER is used at T will not reach 4V and the LTC4252 will not shut the external MOSFET off. To handle this situation, the TIMER discharges C slowly with a 5.8μA pull-down whenever the SENSE T voltage is less than 50mV ...
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... Unduly long soft-start intervals can exceed the MOSFET’s SOA rating if powering up into an active load floats, an internal current source ramps SS from 0V DRN to 2.2V for the LTC4252 1.4V for the LTC4252A in about 230μs. Connecting an external capacitor C from SS to ground modifies the ramp to approximate an RC response of: 80 ...
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... SHORT-CIRCUIT OPERATION Circuit behavior arising from a load side low impedance short is shown in Figure 6 for the LTC4252. Initially, the current overshoots the fast current limit level of V 200mV (Trace 2) as the GATE pin works to bring V control (Trace 3). The overshoot glitches the backplane ...
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... Figure 6 Trace 1, can rob charge from output capacitors on adjacent cards. When the faulty card shuts down, current flows in to refresh the capacitors. If LTC4252s are used by the other cards, they respond by limiting the inrush current to a value of 100mV/R ...
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... This gauge is determined empirically with board level evaluation. ) SUMMARY OF DESIGN FLOW (13) To summarize the design flow, consider the application shown in Figure 2 with the LTC4252A. It was designed and for 80W. SUPPLY(MAX) Calculate the maximum load current: 80W/43V = 1.86A; allowing for 83% converter efficiency, I ...
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... MOSFET avalanche. SENSE RESISTOR CONSIDERATIONS For proper circuit breaker operation, Kelvin-sense PCB con- nections between the sense resistor and the LTC4252’s V and SENSE pins are strongly recommended. The drawing in Figure 8 illustrates the correct way of making connections between the LTC4252 and the sense resistor. PCB layout should be balanced and symmetrical to minimize wiring errors ...
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... OS OS GATE INITIAL TIMING START-UP makes contact through a short pin. This ensures the power connections are firmly established before the LTC4252 is activated. At time point 1, the power pins make contact and V ramps through V IN divider makes contact and its voltage exceeds V addition, the internal logic checks for OV < V < ...
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... When GATE ramps past threshold at time point 10, PWRGD pulls low GATEH time point 11, GATE reaches its maximum voltage as – reaches the determined LTC4252-1/LTC4252-2 AND TIMER < TMRL , CHECK GATE < SENSE < V GATEL CB 5.8μA 5.8μA V – ...
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... LTC4252A-1/LTC4252A-2 APPLICATIONS INFORMATION 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 recovers and clears V (time point 2), an initial timer UVHI cycle begins followed by a GATE start-up cycle ...
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... GATEL OVLO V TMRH 5.8μA DRN 58μA V – GATEH 58μ ACL ACL V CB GATE START-UP LTC4252-1/LTC4252-2 AND TIMER < TMRL , CHECK GATE < SENSE < V GATEL CB OS 5.8μA 5.8μA V – GATEH V ACL DRNCL V DRNL 425212 F12 ) EE , SENSE < 5.8μA 425212 F13 ...
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... LKO LKH shutdown cooling cycle spanning time points 2 and 3. At time point 3, the LTC4252 automatic retry occurs with a start-up cycle. Good thermal management techniques are pin. highly recommended; power and thermal dissipation must ...
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... CIRCUIT BREAKER TIMES OUT 1 2 5.8μA DRN 5.8μA TIMER V TMRL GATE SS SENSE V OUT DRAIN PWRGD CB FAULT Figure 16. Shutdown Cooling Timing Behavior of LTC4252-2 (All Waveforms Are Referenced to V LTC4252A-1/LTC4252A-2 SWITCH RESETS LATCHED TIMER SWITCH RELEASES 5.8μA V TMRH 5.8μA DRN V TMRL 58μA V – ...
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... MOSFET can help T D prevent SOA damage in a low impedance fault condition. Soft-Start If the SS pin is not connected, this pin defaults to a linear voltage ramp, from 0V to 2.2V in about 180μs ( 1.4V in 230μs for the LTC4252A) at GATE start-up TMRH DRN ...
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... A soft-start voltage below V CB circuit breaker TIMER. Power Limit Circuit Breaker Figure 19 shows the LTC4252A power limit circuit breaking application. The SENSE pin is modulated by the board supply voltage The D1 Zener voltage, V SUPPLY is set to be the same as the low supply operating voltage 43V ...
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... GS(TH),Q1 and V SUPPLY(MAX) Diode-ORing Figure 22 shows the LTC4252 used as diode-oring with Hot Swap capability in a dual – 48V power supply application. The conventional diode-OR method uses two high power diodes and heat sinks to contain the large heat dissipation of the diodes. With the LTC4252 controlling the external ...
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... INC Figure 21. Inrush Control Without a Sense Resistor Application At power-up, Q5 and Q8 are held off low by the SS pin of the LTC4252; resistors R5 and R8 pull the SENSE pin closed connected to the power supply with EE EE lower voltage through the body diodes until turned on ...
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... DDZ13B UV DRAIN 2 PWRGD Q5 LTC4252-2 FDV301N 10 4 SENSE TIMER GATE 560Ω † D IN3 DDZ13B UV DRAIN 2 PWRGD Q8 LTC4252-2 FDV301N 10 4 TIMER SENSE GATE 560Ω 5 Figure 22. –48V/2.5A Diode-OR Application R IN1 3 × 1.8k IN SERIES 1/4W EACH LOAD † MODULE IN1 1μF ** DDZ13B DRAIN ...
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... LTC4252A-1/LTC4252A-2 the current flow. The sense voltage is lifted up and causes the fast comparator of LTC4252 to trip and pull the GATE low instantly. The channel A supply short will not cause Q3 of channel B diode-OR circuit to turn off. Similarly, when the channel B supply is shorted to the – ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 PACKAGE DESCRIPTION 0.889 ± 0.127 (.035 ± .005) 5.23 3.20 – 3.45 (.206) (.126 – .136) MIN 0.42 ± 0.038 0.65 (.0165 ± .0015) (.0256) TYP BSC RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. ...
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... Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 12, 14, 15, 30, 31, 32, 33 PAGE NUMBER 1, 36 ...
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... Hot Swap Controllers in SOT-23 LTC4253 –48V Hot Swap Controller with Sequencer Linear Technology Corporation 36 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 2× 5.1k IN SERIES 1/4W EACH † DDZ13B LTC4252-1 7 UV/OV DRAIN 8 TIMER GATE SENSE V EE 150nF PUSH 27nF RESET † ...