LTC1773 LINER [Linear Technology], LTC1773 Datasheet
LTC1773
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LTC1773 Summary of contents
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... Synchronous rectification increases efficiency and elimi- nates the need for a Schottky diode, saving components and board space. The LTC1773 comes in a 10-lead MSOP package. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. ...
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... Maximum Current Sense Voltage C = 3000pF (Note 6) LOAD C = 3000pF (Note 6) LOAD C = 3000pF (Note 6) LOAD C = 3000pF (Note 6) LOAD ORDER PART NUMBER 10 SW – LTC1773EMS 9 SENSE PART MARKING 6 BG LTMV = 120°C/W http://www.linear.com/leadfree/ MIN TYP MAX UNITS 20 60 ● ...
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... P according to the following formula: D LTC1773: T Note 4: The LTC1773 is tested in a feedback loop which servos V balance point for the error amplifier (V Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. Note 6: Rise and fall times are measured using 10% and 90% levels. ...
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... LTC1773 W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs V RUN/SS 120 100 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 V (V) RUN/SS 1773 G07 Oscillator Frequency vs Temperature 560 550 540 530 520 – 60 –40 – 100 120 140 TEMPERATURE (°C) 1773 G10 Start-Up ...
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... COMP OSC – 0. FREQ SHIFT EA 0.22V – 1.5µ RUN/SOFT RUN/ 2 SOFT-START START RUN/SS R – OVDET + 0.86V – FCB + Figure 2. LTC1773 . 0.4V 9 SENSE EN + – – SLEEP I COMP 50mV + BURST COMP SWITCHING LOGIC AND ANTI BLANKING SHOOT-THRU CIRCUIT ...
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... The top MOSFET turn-on follows the rising edge of the external source. When the LTC1773 is clocked by an external source, Burst Mode operation is disabled; the LTC1773 then operates in PWM pulse skipping mode preventing current reversal. In this mode, when the output load is very low, current ...
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... SENSE sets the peak of the inductor current, yielding a maximum Low Supply Operation The LTC1773 is designed to operate down to a 2.65V supply voltage. For proper operation at this low input voltage, sub-logic level MOSFETs are required. When the value of the output voltage is very close to the input voltage, the converter is running at high duty cycles or in dropout where the main switch is on continuously ...
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... Power MOSFET and Schottky Diode Selection Two external power MOSFETs must be selected for use with the LTC1773: a P-channel MOSFET for the top (main) switch, and an N-channel MOSFET for the bottom (syn- chronous) switch. . Remember, ...
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... However, due to differ- ences in test and specification methods of various MOSFET manufacturers, the P-channel MOSFET ultimately should be evaluated in the actual LTC1773 application circuit to ensure proper operation. A Schottky diode can be placed in parallel with the syn- chronous MOSFET to improve efficiency. It conducts during the dead-time between the conduction of the two power MOSFETs ...
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... W U Run/Soft-Start Function The RUN/SS pin is a dual purpose pin that provides the soft-start function and a means to shut down the LTC1773. Soft-start reduces surge currents from V increasing the internal current limit. Power supply se- quencing can also be accomplished using this pin. An internal 1.5µA current source charges up an external ...
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... L1, L2, etc. are the individual losses as a percentage of input power Although all dissipative elements in the circuit produce losses, four main sources usually account for most of the losses in LTC1773 circuits: V power MOSFET gate charge current, I topside MOSFET transition losses. 1. The given in the electrical characteristics, it excludes MOSFET driver and control currents ...
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... Minimum On-Time Considerations Minimum on-time, t time that the LTC1773 is capable of turning the top MOSFET on and off again determined by internal timing delays and the gate charge required to turn on the top MOSFET. The minimum on-time for the LTC1773 is about 250ns ...
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... BOLD LINES INDICATE HIGH CURRENT PATHS W U Design Example As a design example, assume the LTC1773 is used in a single lithium-ion battery powered cellular phone applica- tion. The V down to about 2.7V. The load current requirement is a maximum of 2A but most of the time it will be on standby mode, requiring only 2mA ...
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... LTC1773 U U APPLICATIONS INFORMATION For the selection of the external MOSFETs, the R must be guaranteed at 2.5V since the LTC1773 has to operate down to 2.7V. This requirement can be met by the Si9801DY. For the feedback resistors, choose R1 = 80.6k. R2 can then be calculated from equation (2) to be: 33pF 200pF 30k 0.1µF ...
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... DALE WSL-2010 SENSE Figure 9. Single Lithium-Ion to 2.5V/5A Regulator Efficiency Curve for Figure 9 100 3. 100 1000 I (mA) OUT 1773 • G17 LTC1773 2.7V ≤ V ≤ 8. OUT2 5V 100mA + 22µF 6.2V 422k V OUT1 + C 2.5V IN 100µF 2A 10V 80. OUT 220µF 6.3V 1773 TA01 2.7V ≤ ...
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... V SYNC/FCB GND 80. SANYO POSCAP 6TPA150M AVX TPSD227M006R0100 OUT L1: COILTRONICS CTX2-4/BH ELECTRONICS 511-1010 R : IRC LR1206-01-R033-F SENSE Figure 10. Single Lithium-Ion to 3.3V/1A Synchronous Zeta Converter 16 LTC1773 SENSE TH 0.025Ω 9 – SENSE Si9803DY 47µ Si9804DY BG ...
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... SENSE 0.01µ SHDN BYP GND SENSE 0.01Ω 9 – SENSE 0.1µF Si7540DP D2* MBRS340T3 *NOTE: D2 NOT NECESSARY. IF REMOVED, EFFICIENCY DROPS BY 1% LTC1773 2.7V ≤ V ≤ 4.2V IN SENSE V OUT 2. 47µF 3µH 6.3V 4.7µF 6. OUT 47µF 6.3V 1773 TA06 V OUT3 2.5V 150mA 10µF ...
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... RUN/SS SENSE 8 V SYNC/FCB GND BG 118k Si9801DY 1% 100pF D2* 0.1µF MBR0530LT1 *NOTE: D2 NOT NECESSARY. IF REMOVED, EFFICIENCY DROPS BY 1% Current Foldback LTC1773 SENSE 0.01Ω 9 – SENSE 100k 0.1µF Si7540DP 1% 100pF *NOTE: D2 NOT NECESSARY. ...
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... DETAIL “A” SEATING PLANE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX LTC1773 4.5V ≤ V ≤ 5. OUT 1.8V L1 ...
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... LTC1773 U TYPICAL APPLICATIO 33pF 200pF LTC1773 30k RUN/SS SENSE 0.1µ SYNC/FCB GND 40.2k 169k SANYO POSCAP 6TPA150M IN OUT1 OUT2 R : IRC LR1206-01-R050-F SENSE D1: BAS16 RELATED PARTS PART NUMBER DESCRIPTION LTC1622 Low Voltage Current Mode Step-Down DC/DC Controller ...