lt1737is-trpbf Linear Technology Corporation, lt1737is-trpbf Datasheet

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... An optional undervoltage lockout pin halts operation when the application input voltage is too low. An optional external capacitor implements a soft- start function. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 12V-18V to Isolated 15V Converter V ...

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... 1000pF ORDER PART TOP VIEW NUMBER 16 GATE LT1737CGN LT1737CS 13 ENDLY LT1737IGN 12 MINENAB LT1737IS 11 SGND GN PART MARKING 10 UVLO 9 3V OUT 1737 S PACKAGE 1737I 16-LEAD PLASTIC SO = 110°C/W (GN 110°C/W (SO 1.4V unless otherwise noted. C MIN TYP MAX ● 4.1 4.5 ● ...

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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER Current Amplifier V Control Pin Threshold C V Switch Current Limit ISENSE ∆V /∆V ISENSE C Timing f Switching Frequency C Oscillator Capacitor Value OSCAP t Minimum Switch On ...

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LT1737 W U TYPICAL PERFOR A CE CHARACTERISTICS Minimum Input Voltage vs Temperature 4.3 4.2 4.1 4.0 3.9 3.8 –50 – 100 125 TEMPERATURE (°C) 1737 G01 Supply Current vs Temperature ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS Minimum Switch On Time vs Temperature 275 R = 50k TON 250 225 200 175 150 125 –50 – 100 125 TEMPERATURE (°C) 1737 G10 Feedback Amplifier Output Current ...

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LT1737 CTIO S PGND (Pin 1): The power ground pin carries the GATE node discharge current. This is typically a current spike of several hundred mA with a duration of tens of nanosec- onds. It ...

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W BLOCK DIAGRA V CC UVLO BIAS OSCAP OSC FB FDBK 3V OUT 3V REG (INTERNAL) t MINENAB ENDLY ON LOGIC COMP SOFT-START V SFST C LT1737 GATE MOSFET DRIVER PGND I SENSE I AMP SGND LOAD COMPENSATION 1737 BD ...

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LT1737 DIAGRA V SW VOLTAGE V IN GND SWITCH OFF STATE MINIMUM t ON FLYBACK AMP STATE W FLYBACK ERROR A PLIFIER OFF ENABLE DELAY DISABLED MINIMUM ENABLE TIME ...

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U OPERATIO The LT1737 is a current mode switcher controller IC designed specifically for the isolated flyback topology. The Block Diagram shows an overall view of the system. Many of the blocks are similar to those found in traditional designs, ...

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LT1737 U OPERATIO Enable Delay When the output switch shuts off, the flyback pulse appears. However, it takes a finite time until the trans- former primary side voltage waveform approximately rep- resents the output voltage. This is partly due to ...

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U OPERATIO transformer secondary and output capacitor. This has been represented previously by the expression “I ESR.” However generally more useful to convert this expression to an effective output impedance. Because the secondary current only flows during the ...

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LT1737 U U APPLICATIO S I FOR ATIO TRANSFORMER DESIGN CONSIDERATIONS Transformer specification and design is perhaps the most critical part of applying the LT1737 successfully. In addi- tion to the usual list of caveats dealing with high frequency isolated ...

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U U APPLICATIO S I FOR ATIO which reduces the size of the primary-referred flyback pulse used for feedback. This will increase the output voltage target by a similar percentage. Note that unlike leakage spike behavior, this phenomena is load ...

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LT1737 U U APPLICATIO S I FOR ATIO SELECTING OSCILLATOR CAPACITOR VALUE The switching frequency of the LT1737 is set by an external capacitor connected between the OSCAP pin and ground. Recommended values are between 200pF and 33pF, yielding switching ...

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U U APPLICATIO S I FOR ATIO implications regarding output voltage regulation at mini- mum load (see Minimum Load Considerations). A second benefit of the enable delay time function occurs at light load. Under such conditions the amount of energy ...

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LT1737 U U APPLICATIO S I FOR ATIO this frequency the sense resistor will behave like an inductor. Several techniques can be used to tame this potential parasitic inductance problem. First, any resistor used for current sensing purposes must be ...

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U U APPLICATIO S I FOR ATIO UVLO R2 (6a) “Standard” UVLO Divider Topology FREQUENCY COMPENSATION Loop frequency compensation is performed by connect- ing a capacitor from the output of the error amplifier (V pin) to ground. ...

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LT1737 U U APPLICATIO S I FOR ATIO Output Impedance Error An additional error source is caused by transformer sec- ondary current flow through the real life nonzero imped- ances of the output rectifier, transformer secondary and output capacitor. Because ...

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U U APPLICATIO S I FOR ATIO MAXIMUM LOAD/SHORT-CIRCUIT CONSIDERATIONS The LT1737 is a current mode controller. It uses the V node voltage as an input to a current comparator that turns off the output switch on a cycle-by-cycle basis ...

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LT1737 U U APPLICATIO S I FOR ATIO the power paths (primary and secondary). B field (mag- netic) radiation is minimized by keeping MOSFET leads, output diode and output bypass capacitor leads as short as possible. E field radiation is ...

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U TYPICAL APPLICATIO S BASIC APPLICATION WITH 3-WINDING TRANSFORMER Figure 8 shows a compact, low power application of the LT1737. Transformer off-the-shelf VERSA-PAC #VP1-0190, produced by Coiltronics. As manufactured, it consists of six ideally identical independent windings. ...

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LT1737 U TYPICAL APPLICATIO S Overall power supply efficiency and output regulation versus input voltage and load current may be seen in Figures 9 and 10. Available output current is a function of input voltage, varying from 650mA with 8V ...

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U TYPICAL APPLICATIO S APPLICATION WITH 2-WINDING TRANSFORMER The previous application example utilized a 3-winding transformer, the third winding providing only feedback information. Additional circuitry may be employed to provide feedback information, thus allowing the trans- former to be reduced ...

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LT1737 U TYPICAL APPLICATIO S R3 and D2. (Diode D2 prevents reverse emitter/base breakdown in Q1 when MOSFET the “ON” state.) The raw flyback voltage at the drain of MOSFET M1 minus the ...

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U TYPICAL APPLICATIO S therefore requires a physically larger transformer. The larg- est size VERSA-PAC is used, a VP5-0083. Three windings are paralleled for both the primary and secondary. Overall power supply efficiency and output regulation ver- sus load current ...

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LT1737 PACKAGE DESCRIPTIO 0.007 – 0.0098 (0.178 – 0.249) 0.016 – 0.050 (0.406 – 1.270) * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH ...

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... FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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. ...

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... C2A 22µF 25V D1 MBRD640CT IRLZ34S 33µF C2B 15µH 16V 22µF ×4 25V R10 R1 51Ω 0.025Ω 7mA Q = 7mA Q LT/LT 0605 REV A • PRINTED IN THE USA © LINEAR TECHNOLOGY CORPORATION 2000 V = 12V OUT R14 750Ω 5% 1737 F18 1737fa ...