LTC1876EG#TRPBF Linear Technology, LTC1876EG#TRPBF Datasheet

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... In addition, its internal 1A switch allows high current outputs to be generated. Its current mode control scheme provides excellent line and load regulation. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode and OPTI-LOOP are trademarks of Linear Technology Corporation CER ...

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LTC1876 ABSOLUTE AXI U RATI GS (Note 1) Input Supply Voltage (V )......................... 36V to –0.3V IN Topside Driver Voltages (BOOST1, BOOST2) ................................... 42V to –0.3V Switch Voltage (SW1, SW2) ......................... 36V to –5V INTV EXTV , ...

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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER UVLO Undervoltage Lockout V Overvoltage Feedback Threshold OVL I Sense Pins Total Source Current SENSE V MS Master Shutdown Threshold STBYMD V KA Keep-Alive Power On-Threshold STBYMD DF Maximum ...

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LTC1876 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER 3.3V Linear Regulator V 3.3V Regulator Output Voltage 3.3OUT V 3.3V Regulator Load Regulation 3.3IL V 3.3V Regulator Line Regulation 3.3VL PGOOD Output V PGOOD Voltage Low PGL ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Output Current and Mode (Figure 1) 100 Burst Mode 90 OPERATION 80 70 FORCED 60 CONTINUOUS MODE 50 40 CONSTANT FREQUENCY 30 (BURST DISABLE 15V ...

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LTC1876 W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs V (Soft-Start) RUN/ 1.6V SENSE(CM (V) RUN/SS 1876 G10 Load Regulation (Controller) 0.0 ...

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W U TYPICAL PERFOR A CE CHARACTERISTICS EXTV and Switch Resistance vs CC Temperature –50 – 100 125 TEMPERATURE ( C) 1876 G19 Shutdown Latch Thresholds vs Temperature 4.5 LATCH ...

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LTC1876 W U TYPICAL PERFOR A CE CHARACTERISTICS Input Source/Capacitor Instantaneous Current (Figure 2A/DIV V IN 200mV/DIV V SW1 10V/DIV V SW2 10V/DIV 1876 G31 V = 15V 1 s/DIV OUT I = ...

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PIN FUNCTIONS provides a common control point to shut down both control- lers. See the Operation section for details. FCB (Pin 7): Forced Continuous Control Input. This input acts on both controllers and is normally used to ...

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LTC1876 U U FUNCTIONAL DIAGRA 1.19V 1M FREQSET CLK1 OSCILLATOR CLK2 PGOOD V WINDOW OSENSE1 COMPARATOR V OSENSE2 V SEC – 4.5V 0.18 A BINH + R6 FCB + FCB R5 – 3.3V 0.8V OUT + V REF – V ...

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U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC1876 uses a constant frequency, current mode scheme to provide excellent line and load regulation for all its outputs. The step-down controllers have two of its switch drivers operating at ...

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LTC1876 U OPERATIO (Refer to Functional Diagram) cycles, followed by a variable “sleep” interval depending upon the load current. The resultant output voltage ripple is held to a very small value by having the hysteretic comparator after the error amplifier ...

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U OPERATIO (Refer to Functional Diagram) controller has been started and been given adequate time to charge up the output capacitors and provide full-load current, the RUN/SS capacitor is used as a short-circuit time-out circuit. If the output voltage falls ...

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LTC1876 U OPERATIO (Refer to Functional Diagram) path, which could include batteries, switches, trace/con- nector resistances and protection circuitry. Improvements in both conducted and radiated EMI also directly accrue as a result of the reduced RMS input current and voltage. ...

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U U APPLICATIO S I FOR ATIO Selection of Operating Frequency The LTC1876 uses a constant frequency architecture with the frequency determined by an internal oscillator capacitor. This internal capacitor is charged by a fixed current plus an additional current ...

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LTC1876 U U APPLICATIO S I FOR ATIO then, sub-logic level threshold MOSFETs (V should be used. Pay close attention to the BV cation for the MOSFETs as well; most of the logic level MOSFETs are limited to 30V or ...

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U U APPLICATIO S I FOR ATIO Medium voltage (20V to 35V) ceramic, tantalum, OS-CON and switcher-rated electrolytic capacitors can be used as input capacitors, but each has drawbacks: ceramic voltage coefficients are very high and may have audible piezoelec- ...

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LTC1876 U U APPLICATIO S I FOR ATIO discharge during the operating frequency period due to ripple current. The choice of using smaller output capaci- tance increases the ripple voltage due to the discharging term but can be compensated for ...

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U U APPLICATIO S I FOR ATIO operating frequency as discussed in the Efficiency Consid- erations section. The junction temperature can be esti- mated by using the equations given in Note 3 of the Electrical Characteristics. For example, the LTC1876 ...

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LTC1876 U U APPLICATIO S I FOR ATIO BAT85 V IN N-CH LTC1876 TG1 L1 EXTV SW CC BG1 N-CH PGND Figure 6b. Capacitive Charge Pump for EXTV Topside MOSFET Driver Supply (C External bootstrap ...

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U U APPLICATIO S I FOR ATIO Soft-Start/Run Function The RUN/SS1 and RUN/SS2 pins are multipurpose pins that provide a soft-start function and a means to shut down the LTC1876 step-down controllers. Soft-start re- duces the input power source’s surge ...

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LTC1876 U U APPLICATIO S I FOR ATIO The value of the soft-start capacitor C scaled with output voltage, output capacitance and load current characteristics. The minimum soft-start capaci- tance is given by: –4 C > (C )(V ) (10 ...

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U U APPLICATIO S I FOR ATIO approximately 220kHz. The FREQSET pin can be grounded to lower this frequency to approximately 140kHz or tied to the INTV pin to yield approximately 310kHz. The FREQSET CC pin may be driven with ...

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LTC1876 U U APPLICATIO S I FOR ATIO Voltage Positioning Voltage positioning can be used to minimize peak-to-peak output voltage excursions under worst-case transient loading conditions. The open loop DC gain of the control loop is reduced depending upon the ...

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U U APPLICATIO S I FOR ATIO quadrupling the importance of loss terms in the switching regulator system! 4. Transition losses apply only to the topside MOSFET(s), and only when operating at high input voltages (typically 20V or greater). Transition ...

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LTC1876 U U APPLICATIO S I FOR ATIO Low V Applications IN In applications where the input supply is low (<5V), the LTC1876 auxiliary regulator can be used to step-up the input to provide the gate drive to the external ...

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U U APPLICATIO S I FOR ATIO Once the value known, select an inductor that can handle at least 1A without saturating. In addition, ensure that the inductor has a low DCR (copper wire resistance ...

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LTC1876 U U APPLICATIO S I FOR ATIO Automotive Considerations: Plugging into the Cigarette Lighter As battery-powered devices go mobile, there is a natural interest in plugging into the cigarette lighter in order to conserve or even recharge battery packs ...

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U U APPLICATIO S I FOR ATIO Choosing 1% resistors 25.5k and R2 = 32.4k yields an output voltage of 1.816V. The power dissipation on the top side MOSFET can be easily estimated. Choosing a Siliconix Si4412DY results ...

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LTC1876 U U APPLICATIO S I FOR ATIO PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the LTC1876. These items are also illustrated graphically in the ...

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U U APPLICATIO S I FOR ATIO signal ground pin and the ground return of C return to the combined C (–) plates. Within the regula- OUT tor circuitry, are the signal and power grounds kept separate? The regulator signal ...

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LTC1876 U U APPLICATIO S I FOR ATIO – Are the SENSE and SENSE leads routed together with minimum PC trace spacing? The filter capacitor between + – SENSE and SENSE should be as close as possible to ...

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U U APPLICATIO S I FOR ATIO An embarrassing problem, which can be missed in an otherwise properly working switching regulator, results when the current sensing leads are hooked up backwards. The output voltage under this improper hookup will still ...

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LTC1876 U TYPICAL APPLICATIO S 100pF 1 RUN/SS1 2 SENSE1 17.4k 1000pF 1% 3 SENSE1 8.25k OSENSE1 0. FREQSET 0. STBYMD 100pF 7 FCB 8 I TH1 47k 6800pF 9 SGND 100pF 10 ...

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... FLASH SHALL NOT EXCEED .254mm (.010") 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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... SENSE LTC3716 2-Phase DC/DC Controller for Mobile Pentium Processors LTC3728 Dual, 2-Phase 550kHz Synchronous Step-Down Controller Adaptive Power and No R are trademarks of Linear Technology Corporation. SENSE Linear Technology Corporation 36 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 High Efficiency Triple 5V/ 3.3V/12V Power Supply ...