LTC3405 Linear Technology, LTC3405 Datasheet
LTC3405
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LTC3405 Summary of contents
Page 1
... TM Package back reference voltage. The LTC3405 is available in a low profile (1mm) ThinSOT package. For new designs, refer to the LTC3405A data sheet. For fixed 1.5V and 1.8V output versions, refer to the LTC3405A-1.5/LTC3405A-1.8 data sheet. ThinSOT is a trademark of Linear Technology Corporation ...
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... J dissipation P according to the following formula: D LTC3405 Note 4: The LTC3405 is tested in a proprietary test mode that connects V to the output of the error amplifier. FB Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency ORDER PART ...
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... TEMPERATURE ( C) 3405 G06 Input Voltage DS(ON 1.2 1.1 1.0 0.9 MAIN SWITCH 0.8 0.7 0.6 SYNCHRONOUS 0.5 SWITCH 0.4 0.3 0.2 0.1 0 400 500 600 INPUT VOLTAGE (V) 3405 G09 LTC3405 V = 1.8V OUT 10 100 1000 3405 G04 50 75 100 125 3405 G07 3405 G10 sn3405 3405fs 3 ...
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... LTC3405 TYPICAL PERFOR A CE CHARACTERISTICS (From Figure 1a Except for the Resistive Divider Resistor Values Temperature DS(ON) 1 4. 0.8 0.6 0.4 0.2 SYNCHRONOUS SWITCH MAIN SWITCH 0 50 –50 – TEMPERATURE ( C) Switch Leakage vs Temperature 160 V = 5.5V IN RUN = 0V 140 120 100 80 60 SYNCHRONOUS 40 SWITCH ...
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... COUPLED I L 200mA/DIV I LOAD 200mA/DIV V = 3.6V 40 s/DIV 1.8V OUT I 0mA TO 250mA LOAD = Burst Mode OPERATION 3405 G21 (Pin 4): Main Supply Pin. Must be closely decoupled (Pin 5): Feedback Pin. Receives the feedback voltage . Grounding this pin selects Burst IN LTC3405 3405 G22 sn3405 3405fs 5 ...
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... U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC3405 uses a constant frequency, current mode step-down architecture. Both the main (P-channel MOSFET) and synchronous (N-channel MOSFET) switches are internal. During normal operation, the internal top power MOSFET is turned on each cycle when the oscillator ...
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... Another important detail to remember is that at low input supply voltages, the R increases (see Typical Performance Characteristics). There- fore, the user should calculate the power dissipation when the LTC3405 is used at 100% duty cycle with low input voltage (See Thermal Considerations in the Applications Information section). > ...
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... LTC3405 U U APPLICATIO S I FOR ATIO The basic LTC3405 application circuit is shown in Figure 1. External component selection is driven by the load require- ment and begins with the selection of L followed OUT Inductor Selection For most applications, the value of the inductor will fall in the range of 3 ...
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... V 1 OUT 22pF C TO 4.2V R2B IN LTC3405 2 CER RUN 6 5 MODE V FB R2A GND R1 215k 200k 2 Figure 5. Feedforward Injection in an All Ceramic Capacitor Application LTC3405 V OUT 1.5V C OUT 4.7 F CER V OUT 1.5V C OUT1 4.7 F CER 3405 F05 sn3405 3405fs 9 ...
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... LTC3405 U U APPLICATIO S I FOR ATIO In pulse skipping mode, the LTC3405 is stable with a 4.7 F ceramic output capacitor with V applications operating in pulse skipping mode, the circuit shown in Figure 6 can be used When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage charac- teristics of all the ceramics for a given value and size ...
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... where T is the ambient temperature example, consider the LTC3405 in dropout at an input voltage of 2.7V, a load current of 300mA and and the duty cycle ambient temperature From the typical perfor- DS(ON) mance graph of switch resistance, the R P-channel switch approximately 0.94 . There- )(1 – ...
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... U 4. Keep the switching node, SW, away from the sensitive V Design Example As a design example, assume the LTC3405 is used in a single lithium-ion battery-powered cellular phone application. The V 4.2V down to about 2.7V. The load current requirement is a maximum of 0.25A but most of the time it will be in standby mode, requiring only 2mA ...
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... OUTPUT CURRENT (mA) Figure 11b V OUT 1.8V † C OUT 4.7 F CER MURATA LQH3C4R7M34 TAIYO YUDEN CERAMIC JMK107BJ105MA † TAIYO YUDEN CERAMIC JMK212BJ475MG V OUT 100mV/DIV AC COUPLED I L 200mA/DIV I LOAD 200mA/DIV V = 3.6V 40 s/DIV IN I 100mA TO 250mA LOAD = LTC3405 8 87k 1000 3405 F11b 3405 TA01c sn3405 3405fs 13 ...
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... IN 10 100 1000 3405 TA02b Single Li-Ion to 1.8V/200mA Regulator Using All Ceramic Capacitors Optimized for Smallest Footprint 3 2. 22pF TO 4. LTC3405 CER RUN 6 5 MODE V FB 332k GND 200k 2 ** 3405 TA03a = 3. 100 1000 3405 TA03b ...
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... CER 3405 TA04a V OUT 100mV/DIV AC COUPLED I L 200mA/DIV I LOAD 200mA/DIV V = 3.6V 40 s/DIV IN I 100mA TO 250mA LOAD = 3405 TA04c 2.80 – 3.10 (.110 – .118) (NOTE 3) PIN ONE ID .95 .25 – .50 (.037) (.010 – .020) REF (6PLCS, NOTE 2) 1.90 (.074) A1 REF S6 SOT-23 0401 LTC3405 sn3405 3405fs 15 ...
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... 600mA OUT 1.4MHz, MS8 6V 600mA OUT Stable with Ceramic Output Capacitor Fixed Output Version of LTC3405A LT/TP 0302 2K • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2001 3405 TA05c to 600mA 3. 3.3V IN sn3405 3405fs ...