LTC4252-1CMS8 Linear Technology, LTC4252-1CMS8 Datasheet
LTC4252-1CMS8
Specifications of LTC4252-1CMS8
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LTC4252-1CMS8 Summary of contents
Page 1
... 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. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Hot Swap is a trademark of Linear Technology Corporation. ...
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... T = 160°C/W JMAX JA ORDER PART NUMBER MS8 PART MARKING LTC4252-1CMS8 LTC4252-2CMS8 LTC4252-1IMS8 LTC4252-2IMS8 Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. ...
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... Low-to-High Transition ● ● ( for LTC4252A Only) ● 5.85 6.15 6.45 ● 5.25 5.55 5.85 ● Low-to-High Transition ● ● ( for LTC4252A Only) ● 4V 50mV SENSE ● LTC4252-1/-2 LTC4252A-1/-2 TYP MAX MIN TYP MAX UNITS 13 14.5 11 ...
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... DRN TMR Timer Off (Circuit Breaker/ Shutdown Cooling, Sinking TMR = 0µA)] 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 0 ...
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... V (V) IN 4252-1/2 G02 Circuit Breaker Current Limit Voltage V vs Temperature –55 –35 – 105 125 25 65 TEMPERATURE (°C) 4252-1/2 G07 LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A Temperature 2mA –55 –35 – 105 125 TEMPERATURE (°C) 4252-1/2 G03 Undervoltage Lockout V LKO vs Temperature 12.0 11.5 11.0 10.5 10 ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A 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 –15 ...
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... V TMRL 1.0 0.5 0 –55 –35 – 105 125 25 65 TEMPERATURE (°C) 4252-1/2 G19 LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A Temperature GATEL 0.8 UV/ TIMER = 0V 0.7 GATE THRESHOLD BEFORE RAMP-UP 0.6 0.5 0.4 0.3 0.2 0.1 0 –55 –35 – 105 125 ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A TYPICAL PERFOR A CE CHARACTERISTICS I (Circuit Breaker, Sourcing) TMR vs Temperature 280 TIMER = 0µA DRN 260 240 220 200 180 –55 –35 – 105 125 TEMPERATURE (°C) 4252-1/2 G22 TMR DRN 10 1 0.1 0.001 0.01 0 (mA) DRN 4252-1/2 G33 V vs Temperature DRNL 2 ...
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... IN 1.4V 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 conditions: in UVLO undervolt- age condition overvoltage condition, during the initial timing cycle or when the circuit breaker fault times out ...
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... OV pin is set at 6.15V with 0.6V hysteresis > 6.15V, GATE pulls low. When OV returns below 5.55V, GATE start-up begins without an initial timing cycle. The LTC4252A OV pin is set at 5.09V with 102mV hysteresis > 5.09V, GATE pulls low. When OV returns below 4.988V, GATE start-up begins without an initial timing cycle ...
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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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... The flow of current damages the connector pins and glitches the power bus, causing other boards in the system to reset. The LTC4252 is designed to turn on a circuit board supply in a controlled manner, allowing insertion or removal without glitches or connector damage. ...
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... If, owing to an output overload, the voltage drop across R exceeds 50mV, TIMER sources 230µA into C ally charges threshold and the LTC4252 shuts off. If the overload goes away before C reaches 4V and SENSE T measures less than 50mV, C slowly discharges (5.8µ ...
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... PWRGD function on the 10-pin MS package is used. Higher current through R results in higher dissipation IN for R and the LTC4252. An alternative is a separate NPN IN buffer driving the optocoupler as shown in Figure 3. Multiple 1/4W resistors can replace a single higher power R resistor. ...
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... U U APPLICATIO S I FOR ATIO tions, 30kΩ impedance coupled with 300mV UV hyster- esis makes the LTC4252 insensitive to noise. If more noise immunity is desired, add a 1nF to 10nF filter capacitor from UV/ Separate UV and OV pins are available in the 10-pin MS package and can be used for a different operating range such as 35 ...
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... C Intermittent overloads may exceed the 50mV threshold at SENSE, but, if their duration is sufficiently short, TIMER will not reach 4V and the LTC4252 will not shut the external MOSFET off. To handle this situation, the TIMER dis- charges C SENSE voltage is less than 50mV. Therefore, any intermit- ...
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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 • D – 5.8] 2.2V for the LTC4252 1.4V for the LTC4252A in about 230µs. Connecting an external capacitor ground modifies the ramp to approximate an RC response of: ...
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... U 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 in ...
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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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... I SUMMARY OF DESIGN FLOW DRN MAX ( ) (13) To summarize the design flow, consider the application shown in Figure 2 with the LTC4252A. It was designed for 80W. and SUPPLY(MAX) Calculate the maximum load current: 80W/43V = 1.86A; allowing for 83% converter efficiency, I Calculate R = SUPPLY(MAX) Calculate I ...
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... MOSFET avalanche. SENSE RESISTOR CONSIDERATIONS For proper circuit breaker operation, Kelvin-sense PCB connections between the sense resistor and the LTC4252’s V and SENSE pins are strongly recommended. The EE drawing in Figure 8 illustrates the correct way of making connections between the LTC4252 and the sense resistor ...
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... V 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 , the fault TIMER cycle V ramps through V IN makes contact and its voltage exceeds V the internal logic checks for OV < ...
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... When GATE ramps past V threshold at time point 10, PWRGD pulls low. At GATEH time point 11, GATE reaches its maximum voltage as – reaches the determined LTC4252-1/LTC4252 < 20 • V AND TIMER < TMRL , CHECK GATE < SENSE < V AND SS < 20 • V ...
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... 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 recovers and clears V (time point 2), an initial timer UVHI cycle begins followed by a GATE start-up cycle ...
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... I DRN 58µA V – GATEH 58µA 20 • ACL OS 20 • • ACL V CB GATE START-UP LTC4252-1/LTC4252-2 AND TIMER < TMRL , CHECK GATE < SENSE < V AND SS < 20 • V GATEL CB 12 5.8µA 5.8µA V – GATEH V ACL DRNCL V DRNL 4252-1/2 F12 ) EE , SENSE < ...
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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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... I 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 SWITCH RESETS LATCHED TIMER SWITCH RELEASES 5.8µA V TMRH 230µ • I 5.8µA ...
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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 230µ • I ...
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... A soft-start voltage below V will not activate the circuit CB 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 zener voltage, V SUPPLY to be the same as the low supply operating voltage 43V ...
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... V OUT Inrush Control Without a Sense Resistor During Power-Up Figure 21 shows the LTC4252A in an application where the inrush current is controlled without a sense resistor dur- ing power-up. This setup is suitable only for applications that don’t require short-circut protection from the LTC4252A ...
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... EE EE lower voltage through the body diodes until turned on. This allows the LTC4252 to perform a start-up cycle and ramp up the SS and GATE voltage. As the SS voltage ramps up to 2.2V, it turns on Q5 and Q8 and pulls TIMER low through Q6 and Q9. The sense ...
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... UV C IN2 2 PWRGD 1µF LTC4252-2 FDV301N 10 4 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 DRAIN ...
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... LTC4252A-1/LTC4252A 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 – 48V RTN (or GND), large current flows into Q7 momen- ...
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... LTC4252-1/LTC4252-2 LTC4252A-1/LTC4252A-2 PACKAGE DESCRIPTIO 5.23 (.206) MIN 0.42 ± 0.038 (.0165 ± .0015) TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 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) 1.10 (.043) DETAIL “A” MAX 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 0.86 ( ...
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... LTC4251/LTC4251-1 – 48V 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 LTC4252-1 7 UV/OV DRAIN 8 TIMER GATE SENSE V EE 150nF 4 C ...