ltc3405a Linear Technology Corporation, ltc3405a Datasheet
ltc3405a
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ltc3405a Summary of contents
Page 1
... The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.8V feed- back reference voltage. The LTC3405A is available in a low profile (1mm) ThinSOT package. For fixed 1.5V and 1.8V output versions, refer to the LTC3405A-1 ...
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... T J dissipation P according to the following formula: D LTC3405A Note 4: The LTC3405A 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 ...
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... TEMPERATURE (°C) Output Voltage vs Load Current 1.834 1.824 1.814 Burst Mode OPERATION 1.804 1.794 PULSE SKIPPING MODE 1.784 1.774 0 200 300 400 6 100 LOAD CURRENT (mA) LTC3405A Efficiency vs Output Current 100 1.8V 40 0.1 1000 ...
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... LTC3405A W U 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 50 100 125 –50 – TEMPERATURE (°C) 3405A G11 Switch Leakage vs Temperature 160 V = 5.5V IN RUN = 0V 140 ...
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... GND, Pin 2, with a 2.2µF or greater ceramic capacitor. V (Pin 5): Feedback Pin. Receives the feedback voltage FB from an external resistive divider across the output. MODE (Pin 6): Mode Select Input. To select pulse skip- ping mode, tie to V Mode operation. Do not leave this pin floating. LTC3405A Load Step V OUT 100mV/DIV AC COUPLED I ...
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... Comparator OVDET guards against transient overshoots > 6.25% by turning the main switch off and keeping it off until the fault is removed. Burst Mode Operation The LTC3405A is capable of Burst Mode operation in which the internal power MOSFETs operate intermittently pin, described in FB based on load demand. To enable Burst Mode operation, simply connect the MODE pin to GND ...
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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 LTC3405A is used at 100% duty cycle with low input voltage (See Thermal Considerations in the Applications Information section). Low Supply Operation The LTC3405A will operate with input supply voltages as low as 2 ...
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... The choice of which style induc- tor to use often depends more on the price vs size require- ments and any radiated field/EMI requirements than on (1) what the LTC3405A requires to operate. Table 1 shows some typical surface mount inductors that work well in LTC3405A applications. C ...
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... ESR make them ideal for switching regulator applications. Because the LTC3405A’s control loop does not depend on the output capacitor’s ESR for stable operation, ceramic capacitors can be used freely to achieve very low output ripple and small circuit size ...
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... SW node will become high impedance. To avoid the LTC3405A from exceeding the maximum junction temperature, the user will need to do some thermal analysis. The goal of the thermal analysis is to determine whether the power dissipated exceeds the maximum junction temperature of the part ...
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... A R where T is the ambient temperature example, consider the LTC3405A in dropout at an input voltage of 2.7V, a load current of 300mA and an ambient temperature of 70°C. From the typical perfor- mance graph of switch resistance, the R P-channel switch at 70°C is approximately 0.94Ω. There- fore, power dissipated by the part is: ...
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... OUT 5. Keep the switching node, SW, away from the sensitive V node. FB Design Example As a design example, assume the LTC3405A is used in a single lithium-ion battery-powered cellular phone application. The V will be operating from a maximum of IN 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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... Figure 7a 100 100 OUTPUT CURRENT (mA) 3405A F07b Figure 7b V OUT 100mV/DIV AC COUPLED I L 200mA/DIV I LOAD 200mA/DIV V = 3.6V 20µs/DIV 2.5V OUT I 100mA TO 300mA LOAD = 3405A F07c Figure 7c LTC3405A V OUT 2. OUT 4.7µF CER 1000 3405afa 13 ...
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... AVX TAJA226M006R 3405A TA01a V OUT 100mV/DIV AC COUPLED 200mA/DIV I LOAD 200mA/DIV 1000 3405A TA01b Single Li-Ion to 1V/200mA Regulator 3.3µ 22pF LTC3405A 4.7µF 1 CER RUN 6 5 MODE V FB 249k GND TAIYO YUDEN LM2016T3R3M ** TAIYO YUDEN CERAMIC JMK212BJ475MG OUT 100mV/DIV = 4 ...
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... U S6 Package 6-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1636) 1.22 REF 1.50 – 1.75 2.80 BSC 1.4 MIN (NOTE 4) 0.95 BSC 0.80 – 0.90 1.00 MAX 0.09 – 0.20 (NOTE 3) LTC3405A 2.90 BSC (NOTE 4) PIN ONE ID 0.30 – 0.45 6 PLCS (NOTE 3) 0.01 – 0.10 1.90 BSC S6 TSOT-23 0302 15 3405afa ...
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... Constant Frequency, I Regulation, V Constant Off-Time from 2.5V to 5.5V IN 1.19V V V from 2.65V to 8. 25V Input, 8-Lead MSOP Package 550kHz, 6-Lead ThinSOT, V 550kHz, MS8, V 550kHz, MS8, V 1.4MHz, MS8, V Fixed Output Versions of the LTC3405A www.linear.com ● V OUT 1. OUT 2.2µF CER OUT 3.6V 20µ ...