LT1956IGN#TR Linear Technology, LT1956IGN#TR Datasheet

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... A shutdown pin reduces supply current and the device can be externally synchronized from 580kHz to 700kHz with a logic level input. The LT1956/LT1956-5 are available in fused-lead 16-pin SSOP and thermally enhanced TSSOP packages. , LTC and LT are registered trademarks of Linear Technology Corporation. *U.S. PATENT NO. 6,498,466 MMSD914TI 0 ...

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LT1956/LT1956 ABSOLUTE AXI U RATI GS Input Voltage (V ) ................................................. 60V IN BOOST Pin Above SW ............................................ 35V BOOST Pin Voltage ................................................. 68V SYNC, SENSE Voltage (LT1956-5) ........................... 7V SHDN Voltage ........................................................... 6V BIAS Pin Voltage ...

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ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the full operating temperature range, otherwise specifications are 15V 1.5V, SHDN = 1V, Boost o/c, SW o/c, unless otherwise noted PARAMETER Switch Current Limit ...

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LT1956/LT1956 TYPICAL PERFOR A CE CHARACTERISTICS Switch Peak Current Limit 2.5 TYPICAL 2.0 GUARANTEED MINIMUM 1.5 1 100 DUTY CYCLE (%) 1956 G01 Lockout and Shutdown Thresholds 2.4 LOCKOUT 2.0 1.6 1.2 0.8 ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS Switching Frequency 575 550 525 500 475 450 425 0 –50 – 100 125 JUNCTION TEMPERATURE ( C) 1956 G10 V Pin Shutdown Threshold C 2.1 1.9 1.7 1.5 1.3 ...

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LT1956/LT1956 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 LT1956 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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LT1956/LT1956 APPLICATIO S I FOR ATIO FEEDBACK PIN FUNCTIONS The feedback (FB) pin on the LT1956 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 LT1956 AMPLIFIER Q2 V GND C with high input voltage. High frequency pickup will in- crease and the protection accorded by frequency and current foldback will decrease. CHOOSING THE INDUCTOR For most applications, ...

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LT1956/LT1956 APPLICATIO S I FOR ATIO Peak-to-peak output ripple voltage is the sum of a triwave (created by peak-to-peak ripple current (I and a square wave (created by parasitic inductance (ESL) and ripple current slew rate). Capacitive reactance ...

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... Additional Considerations After making an initial choice, consider additional factors such as core losses and second sourcing, etc. Use the experts in Linear Technology’s Applications department if you feel uncertain about the final choice. They have experience with a wide range of inductor types and can tell you about the latest developments in low profile, surface mounting, etc ...

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LT1956/LT1956 APPLICATIO S I FOR ATIO solution. The maximum output load current in discontinu- ous mode, however, must be calculated and is defined later in this section. Discontinuous mode is entered when the output load current is less ...

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U U APPLICATIO S I FOR ATIO where switching frequency t = switch minimum on time diode forward voltage input voltage IN I • inductor I • R voltage drop ...

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LT1956/LT1956 APPLICATIO S I FOR ATIO Output capacitor ripple current (RMS OUT IN I RIPPLE RMS ( ) Ceramic Capacitors Ceramic capacitors are generally chosen for their good high ...

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U U APPLICATIO S I FOR ATIO internal switch will ramp up V current into the diode attempt to get it to recover. Then, when the diode has finally turned off, some tens of nanoseconds later, the ...

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LT1956/LT1956 APPLICATIO S I FOR ATIO INPUT bypassed with a 1000pF capacitor to prevent coupling problems from the switch node. If hysteresis is desired in the undervoltage lockout point, a resistor R added ...

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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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LT1956/LT1956 APPLICATIO S I FOR ATIO Board layout also has a significant effect on thermal resis- tance. For the GN package, Pins and 16, GND, are a continuous copper plate that runs under the LT1956 ...

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U U APPLICATIO S I FOR ATIO Boost current loss OUT OUT P BOOST V IN Quiescent current loss 0015 . V 0 003 . Q IN OUT R = switch resistance ...

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LT1956/LT1956 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 Input Voltage vs Operating Frequency Considerations The absolute maximum input supply voltage for the LT1956 is specified at 60V. This is based on internal semiconduc- tor junction breakdown effects. The practical maximum input ...

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LT1956/LT1956 APPLICATIO S I FOR ATIO LT1956 CURRENT MODE SW POWER STAGE ERROR g = 2mho m AMPLIFIER – 2000 mho + R 1.22V O 200k GND ...

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U U APPLICATIO S I FOR ATIO D3 10MQ060N REMOVABLE INPUT R3 54k R4 25k Figure 12. Dual Source Supply with 25 A Reverse Leakage INPUT 12V C3 2.2 F CERAMIC current via the V pin to maintain a constant ...

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LT1956/LT1956 APPLICATIO S I FOR ATIO 12V (TRANSIENTS TO 36V) C3 2.2 F 50V CERAMIC GND *SUMIDA CDRH4D28-150 **SEE FIGURE 14c FOR V LOAD CURRENT RELATIONSHIP † IF LOAD CAN GO TO ZERO, AN ...

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U U APPLICATIO S I FOR ATIO current in L2 and C4 flows via the catch diode D3, charging the negative output capacitor C6. If the negative output is not loaded enough, it can go severely unregulated (be- come more ...

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LT1956/LT1956-5 PACKAGE DESCRIPTIO Minimum inductor continuous mode OUT L MIN – OUT P OUT For a 12V to –12V converter using the LT1956 with peak ...

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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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... LT1767 Monolithic 1.5A, 1.25MHz Step-Down Regulator LT1776 Wide Input Range, High Efficiency, Step-Down Switching Regulator LT1777 Low Noise Buck Regulator 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 U GN Package 16-Lead Plastic SSOP (Narrow ...