lt3431efe-trpbf Linear Technology Corporation, lt3431efe-trpbf Datasheet

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... A shutdown pin reduces supply current and the de- vice can be externally synchronized from 580kHz to 700kHz with logic level inputs. The LT3431 is available in a thermally enhanced 16-pin TSSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. MMSD914TI 0. H ...

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... SYNC Voltage ........................................................... 7V SHDN Voltage ........................................................... 6V BIAS Pin Voltage .................................................... 30V FB Pin Voltage/Current .................................. 3.5V/2mA Operating Junction Temperature Range LT3431EFE (Notes 8, 10) ................. – 125 C LT3431IFE (Notes 8, 10) ................. – 125 C Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 C ELECTRICAL CHARACTERISTICS The ...

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... Note 7: Switch on resistance is calculated by dividing V the forced current (3A). See Typical Performance Characteristics for the graph of switch voltage at other currents. Note 8: The LT3431EFE is guaranteed to meet performance specifications from 125 C junction temperature. Specifications over the – 125 C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3431IFE is guaranteed over the full – ...

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LT3431 W U TYPICAL PERFOR A CE CHARACTERISTICS Switch Peak Current Limit TYPICAL 4 GUARANTEED MINIMUM 100 DUTY CYCLE (%) 3431 G01 Lockout and Shutdown Thresholds ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS Switching Frequency 575 550 525 500 475 450 425 –50 – 100 125 JUNCTION TEMPERATURE ( C) 3431 G10 V Pin Shutdown Threshold C 2.1 1.9 1.7 1.5 1.3 ...

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LT3431 CTIO S GND (Pins 16): The GND pin connections act as the reference for the regulated output, so load regulation will suffer if the “ground” end of the load is not ...

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W BLOCK DIAGRA The LT3431 is a constant frequency, current mode buck converter. This means that there is an internal clock and two feedback loops that control the duty cycle of the power switch. In addition to the normal error ...

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LT3431 U U APPLICATIO S I FOR ATIO FEEDBACK PIN FUNCTIONS The feedback (FB) pin on the LT3431 is used to set output voltage and provide several overload protection features. The first part of this section deals with selecting resistors ...

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U U APPLICATIO S I FOR ATIO LT3431 AMPLIFIER Q2 V GND C will increase and the protection accorded by frequency and current foldback will decrease. CHOOSING THE INDUCTOR For most applications, the output inductor will fall into the range ...

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LT3431 U U APPLICATIO S I FOR ATIO importance, the subsequent suggestions in Peak Induc- tor and Fault Current and EMI will additionally help in the selection of the inductor value. Peak-to-peak output ripple voltage is the sum of a ...

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U U APPLICATIO S I FOR ATIO there are no helpful guidelines to calculate when the magnetic field radiation will be a problem. Table 2 VENDOR/ VALUE I DC PART NUMBER ( H) (Amps) Sumida CDRH8D28-4R7 4.7 3.4 CDRH8D28-7R3 7.3 ...

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LT3431 U U APPLICATIO S I FOR ATIO To calculate actual peak switch current with a given set of conditions, use OUT SW PEAK OUT F I OUT ...

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U U APPLICATIO S I FOR ATIO time involved in both the current comparator and turnoff of the output switch. These result in a minimum on time t . When combined with the large ratio of V ON(MIN ...

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LT3431 U U APPLICATIO S I FOR ATIO Many engineers have heard that solid tantalum capacitors are prone to failure if they undergo high surge currents. This is historically true, and type TPS capacitors are specially tested for surge capability, ...

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U U APPLICATIO S I FOR ATIO If tantalum capacitors are used, values in the 470 F range are generally needed to minimize ESR and meet ripple current and surge ratings. Care should be taken to ensure ...

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LT3431 U U APPLICATIO S I FOR ATIO INPUT Threshold voltage for lockout is about 2.38V. A 5.5 A bias current flows out of the pin at this threshold. The internally generated current is used ...

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U U APPLICATIO S I FOR ATIO reduced. This type of subharmonic switching only occurs at input voltages less than twice output voltage. Higher inductor values will tend to eliminate this problem. See Frequency Compensation section for a discussion of ...

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LT3431 U U APPLICATIO S I FOR ATIO The V and FB components should be kept as far away as C possible from the switch and boost nodes. The LT3431 pinout has been designed to aid in this. The ground ...

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U U APPLICATIO S I FOR ATIO Switch loss OUT OUT EFF V IN Boost current loss OUT OUT P BOOST V IN Quiescent current loss: P ...

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LT3431 U U APPLICATIO S I FOR ATIO Note: Some of the internal power dissipation in the IC, due to BOOST pin voltage, can be transferred outside of the IC to reduce junction temperature, by increasing the voltage drop in ...

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U U APPLICATIO S I FOR ATIO A detailed theoretical basis for estimating internal power dissipation is given in the Thermal Calculations section. This will allow a first pass check of whether an application’s maximum input voltage requirement is suitable ...

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LT3431 U U APPLICATIO S I FOR ATIO tantalum output capacitor with a ceramic output capacitor because of its very low ESR. The zero provided by the tantalum output capacitor must now be reinserted back into the loop. Alternatively there ...

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U U APPLICATIO S I FOR ATIO BUCK CONVERTER WITH ADJUSTABLE SOFT-START Large capacitive loads or high input voltages can cause high input currents at start-up. Figure 13 shows a circuit that limits the dv/dt of the output at start-up, ...

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... V LOAD CURRENT (mA) OUT1 3431F14b Figure 14b. V (–5V) Maximum OUT2 Allowable Load Current vs V OUT1 (5V) Load Current MMSD914T1 C2 0. BOOST IN SW SHDN V LT3431EFE OUT1 SYNC BIAS 15.4k 6.3V F 0805 B R3 X5R GND V C 4.99k CER 1.5k F 220pF ...

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U U APPLICATIO S I FOR ATIO POSITIVE-TO-NEGATIVE CONVERTER The circuit in Figure positive-to-negative topology using a grounded inductor. It differs from the standard approach in the way the IC chip derives its feedback signal because the ...

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LT3431 U U APPLICATIO S I FOR ATIO For a load current of 0.5A, this says that discontinuous mode can be used and the minimum inductor needed is found from ...

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... DIMENSIONS ARE IN 3. DRAWING NOT TO SCALE 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights Package 16-Lead Plastic TSSOP (4 ...

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... Step-Down DC/DC Converter LTC3412 2. 4MHz, Synchronous OUT Step-Down DC/DC Converter LT3430 60V, 2.75A (I ), 200kHz, High Efficiency OUT Step-Down DC/DC Converter ThinSOT is a trademark of Linear Technology Corporation. Linear Technology Corporation 28 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 COMMENTS V = 7.3V to 45/64V DD-5/7, TO220-5/7 Packages ...