LT1976EFE Linear Technology, LT1976EFE Datasheet

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... Distributed Power Systems Battery-Powered Systems ■ , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents, including 6498466 **See Burst Mode Operation section for conditions ...

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... BOOST Pin Voltage ................................................. 68V SYNC PGFB, FB ................................................ 6V SS Operating JunctionTemperature Range LT1976EFE/LT1976BEFE (Note 2) ... – 40°C to 125°C LT1976IFE/LT1976BIFE (Note 2) ..... – 40°C to 125°C LT1976HFE (Note 2) ........................ – 40°C to 140°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C ...

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ELECTRICAL CHARACTERISTICS operating temperature range, otherwise specifications are at T FB/PGFB = 1.25V, C /SYNC = 0V unless otherwise noted. SS SYMBOL PARAMETER I SW Current Limit PK Switch On Resistance (Note 9) Switching Frequency Maximum Duty Cycle Minimum SYNC ...

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... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT1976EFE/LT1976BEFE are guaranteed to meet performance specifications from 0°C to 125°C junction temperature. Specifications over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS LT1976 Efficiency and Power Loss vs Load Current 100 EFFICIENCY 75 5V 3.3V 50 TYPICAL POWER LOSS 25 0 0.1 1 100 1000 10000 10 LOAD CURRENT (mA) 1976 TA02 Oscillator Frequency 250 ...

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LT1976/LT1976B W U TYPICAL PERFOR A CE CHARACTERISTICS PGFB Threshold 1.20 1.18 1.16 1.14 1.12 1.10 1.08 1.06 1.04 1.02 1.00 – 100 125 150 –25 TEMPERATURE (°C) 1976 G08 Soft-Start Current Threshold vs FB Voltage ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS LT1976B V Switching Threshold C vs Temperature 700 600 500 400 300 200 100 0 –50 –30 – 110 TEMPERATURE (˚C) 1976 G26 Dropout Operation 4 ...

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LT1976/LT1976B W U TYPICAL PERFOR A CE CHARACTERISTICS CTIO S NC (Pins 1, 3, 5): No Connection. Pins are electrically isolated from the LT1976. They may be con- nected to PCB traces ...

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CTIO S C (Pin 9): A capacitor from the output voltage determines the output voltage ramp rate during start-up. When the current through the C tor exceeds the C threshold (I SS ...

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LT1976/LT1976B W BLOCK DIAGRA V IN INTERNAL REF 4 UNDERVOLTAGE LOCKOUT BIAS THERMAL 10 SHUTDOWN SYNC 14 SHDN + 15 SHDN COMP – 1. SOFT-START FOLDBACK DETECT FB – 12 ERROR AMP + 1.25V ...

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W BLOCK DIAGRA power from the V pin, but if the BIAS pin is connected external voltage higher than 3V bias power will be drawn from the external source (typically the regulated output voltage). This improves efficiency. ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO FEEDBACK PIN FUNCTIONS The feedback (FB) pin on the LT1976 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 capacitive loads or high input voltages can cause a high input current surge during start-up. The soft-start func- tion reduces input current surge by regulating switch current via the V pin to maintain ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO Table 3. Surface Mount Solid Tantalum Capacitor ESR and Ripple Current E CASE SIZE ESR MAX (Ω) AVX TPS 0.1 to 0.3 D CASE SIZE AVX TPS 0.1 to 0.3 C CASE ...

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U U APPLICATIO S I FOR ATIO Example: with V = 12V 3.3V 33μH, ESR = IN OUT 0.08Ω, ESL = 10nH – ...

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... After making an initial choice, consider the secondary 0.17 8 things like output voltage ripple, second sourcing, etc. Use the experts in the Linear Technology’s applications 0.1 3 department if you feel uncertain about the final choice. 0.3 3 They have experience with a wide range of inductor ...

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U U APPLICATIO S I FOR ATIO Short-Circuit Considerations The LT1976 is a current mode controller. It uses the V node voltage as an input to a current comparator which turns off the output switch on a cycle-by-cycle basis as ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO C = GND SS V OUT 0.5V/DIV C = 0.1μ 47μF TIME (1ms/DIV) OUT I = 200mA LOAD V = 12V IN Figure 4. V dV/dt OUT ...

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U U APPLICATIO S I FOR ATIO drops to 15μA. The PG pin will be active low during the “on” portion of the SHDN waveform due to the C tor discharge when SHDN is taken low. See the Power Good ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO OPTIONAL V V BOOST IN IN LT1976 GND SW V – BOOST SW OUT BOOST(MAX) IN OUT (7a BOOST IN IN LT1976 ...

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U U APPLICATIO S I FOR ATIO OUT R2 See the Typical Performance Characteristics section for graphs of SHDN and V currents verses input voltage. IN SYNCHRONIZING Oscillator synchronization to an external input is achieved by connecting ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO (I ) from the C pin into the external capacitor. When the CT T voltage on the external capacitor reaches an internal clamp (V ), the PG pin becomes a high impedance ...

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U U APPLICATIO S I FOR ATIO LAYOUT CONSIDERATIONS As with all high frequency switchers, when considering layout, care must be taken in order to achieve optimal electrical, thermal and noise performance. For maximum efficiency switch rise and fall times ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO Board layout also has a significant effect on thermal resistance. Pin 8 and the exposed die pad, Pin 17, are a continuous copper plate that runs under the LT1976 die. This is ...

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U U APPLICATIO S I FOR ATIO HIGH TEMPERATURE OPERATION Extreme care must be taken when designing LT1976 applications to operate at high ambient temperatures. The LT1976H grade is designed to work at elevated tempera- tures but erratic operation can ...

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LT1976/LT1976B U U APPLICATIO S I FOR ATIO The LT1976 uses current mode control. This alleviates many of the phase shift problems associated with the inductor. The basic regulator loop is shown in Figure 12. The LT1976 can be considered ...

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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. V OUT 3 ...

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... I : 100μA, TSSOP-16E IN OUT Q : 3.3V to 60V 1.25V 100μ OUT(MIN 36V 0.8V 670μ 20μA, IN OUT(MIN LT/CGRAFX 0407 REV G PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2003 : 2.5μA, : 25μA, : 30μA, : 25μA, : <1μA, : <1μA, : 30μA, : 30μA, : <1μA, 1976bfg ...