LTC3549 Linear Technology, LTC3549 Datasheet
LTC3549
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LTC3549 Summary of contents
Page 1
... OUT Supply current during Burst Mode operation is only 50µA dropping to < 1µA in shutdown. The 1.6V to 5.5V input voltage range makes the LTC3549 ideally suited for single cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd or NiMH battery-powered applications. 100% duty cycle capabil- ity provides low dropout operation, extending battery life in portable systems. Burst Mode operation can be user-enabled, increasing effi ...
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... IN 6-LEAD (2mm × 3mm) PLASTIC DFN ORDER PART NUMBER LTC3549EDCB Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. ...
Page 3
... Continuous operation above the specifi ed maximum operating junction temperature may impair device reliability. Note 4: The LTC3549 is tested in a proprietary test mode that connects V to the output of the error amplifi er. Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. Note 6: Δ ...
Page 4
... LTC3549 W TYPICAL PERFOR A CE CHARACTERISTICS (From Typical Application on the front page, except for the resistive divider resistor values) Effi ciency/Power Loss vs Load Current 1.5V, Burst Mode OUT 100 www.DataSheet4U.com 100 LOAD CURRENT (mA) EFFICIENCY POWER LOSS 1.8V ...
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... Switch Leakage vs Temperature V = 5.5V IN 250 200 150 SYNCHRONOUS SWITCH 100 MAIN SWITCH 50 0 125 –50 – TEMPERATURE (°C) 3549 G13 LTC3549 Output Voltage vs Load Current V = 1.6V 1.2V IN OUT 1.205 1.204 1.203 1.202 BURST 1.201 1.200 V OUT PULSE SKIP 1.199 5.5 0 100 ...
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... LTC3549 W TYPICAL PERFOR A CE CHARACTERISTICS (From Typical Application on the front page, except for the resistive divider resistor values) Start-Up from Shutdown Burst Mode Operation V OUT 500mV/DIV V 1V/DIV RUN I L www.DataSheet4U.com 50mA/DIV 1.2V OUT 1kΩ Load Load Step 25mA to 250mA Pulse Skip ...
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... GND (Pin 7): Exposed Pad. The Exposed Pad is ground. It must be soldered to PCB ground to provide both electrical contact and optimum thermal performance. W SLOPE COMP OSC – – + 0.4V EA BURST LATCH OV LTC3549 0.65V SLEEP 5Ω + – I COMP SWITCHING LOGIC ANTI- AND SHOOT- BLANKING THRU CIRCUIT + I RCMP – V ...
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... Another important detail to remember is that at low input supply voltages, the R increases (see Typical Performance Characteristics). Therefore, the user should calculate the power dissipation when the LTC3549 is used at 100% duty cycle with low input voltage (see Thermal Considerations in the Applica- tions Information section). Slope Compensation > ...
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... The start- APPLICATIO S I FOR ATIO The basic LTC3549 application circuit is shown on the fi rst page of this data sheet. External component selection is www.DataSheet4U.com driven by the load requirement and begins with the selection of L followed by C and C ...
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... Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. Because the LTC3549’s control loop does not depend on the output capacitor’s ESR for stable operation, ceramic capacitors can be used to achieve very low output ripple and small circuit size ...
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... Effi ciency = 100% – ( ...) where L1, L2, etc. are the individual losses as a percent- age of input power. www.DataSheet4U.com Although all dissipative elements in the circuit produce losses, two main sources usually account for most of the losses in LTC3549 circuits losses. The V quiescent current loss dominates IN the effi ...
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... A R where T is the ambient temperature example, consider the LTC3549 in dropout at an input voltage of 1.6V, a load current of 250mA and an ambient temperature of 75°C. In the Switch Resistance graph shown in the Typical Performance Characteristics, the R of the P-channel switch at 75°C is approximately DS(ON) 0.8Ω ...
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... APPLICATIO S I FOR ATIO Board Layout Considerations When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the LTC3549. These items are also illustrated graphically in the layout diagram of Figure 3. Check the following in your layout. 1. Does the capacitor C ...
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... U U APPLICATIO S I FOR ATIO Design Example As a design example, assume the LTC3549 is used in a 2-alkaline cell battery-powered application. The V operating from a maximum of 3.1V down to about 1.8V. The load current requirement is a maximum of 250mA but most of the time it will be in standby mode, requiring only 2mA. Effi ...
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... ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE LTC3549 R = 0.115 0.40 ± 0.10 TYP 4 6 PIN 1 NOTCH R0 ...
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... Step-Down DC/DC Converter VLDO and ThinSOT are trademarks of Linear Technology Corporation. Linear Technology Corporation 16 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● U L1, 4.7µ 2.5V TO RUN SW C 4.2V IN LTC3549 4.7µF CERAMIC MODE FB GND R2 137k *TDK VLF3012AT-4R7MR74 3549 TA03a = 3. 4. ...