ltc3541 Linear Technology Corporation, ltc3541 Datasheet

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... Small, Thermally Enhanced, 10-Lead (3mm × 3mm) ■ DFN Package APPLICATIO S U PDAs/Palmtop PCs ■ Digital Cameras ■ Cellular Phones ■ PC Cards ■ Wireless and DSL Modems ■ Other Portable Power Systems ■ TYPICAL APPLICATIO U LTC3541 Typical Application V IN 2.9V TO 5.5V SW ENVLDO V MODE 2.2µH IN LTC3541 243k ENBUCK GND V OUT1 BUCKFB LFB 22pF 2.5V ...

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... LFB (Note PACKAGE/ORDER I FOR ATIO + 0.3V) IN EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB ORDER PART NUMBER LTC3541EDD Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. The denotes the specifications which apply over the full operating ● = 25° 3.6V unless otherwise specified (Note 2) ...

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... Input Pin Current MODE I , ENBUCK I ENVLDO Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3541 is guaranteed to meet performance specifications from 0°C to 85°C. VLDO/linear regulator output is tested and specified under pulse load conditions such that T ≈ and are 100% production J A tested at 25°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Minimum operating LV ...

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... LTC3541 TYPICAL PERFOR A CE CHARACTERISTICS W U Efficiency vs Input Voltage for Buck (Burst) 100 V = 1.8V OUT 500mA OUT 100mA OUT 30mA OUT INPUT VOLTAGE (V) 3541 G01 Efficiency vs Load Current for Buck (Pulse Skip) 100 V = 1.8V OUT ...

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... Buck (Burst) Load Step from 1mA to 500mA V OUT 100mV/DIV AC COUPLED I L 500mA/DIV I LOAD 500mA/DIV 3541 G16 V = 3.6V 40µs/DIV 1.8V OUT I = 1mA TO 500mA LOAD LTC3541 VLDO/Linear Regulator Reference vs Temperature 0.410 V = 3.6V IN 0.408 0.406 0.404 0.402 0.400 0.398 0.396 0.394 0.392 0.390 –50 – TEMPERATURE (° ...

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... LTC3541 TYPICAL PERFOR A CE CHARACTERISTICS W U VLDO Load Step from 100mA to 300mA LV OUT 20mV/DIV AC COUPLED I LOAD 250mA/DIV V = 3.6V 400µs/DIV 1.5V OUT I = 100mA TO 300mA LOAD VLDO to Linear Regulator Transient Step, Load = 1mA LV OUT 10mV/DIV AC COUPLED I LOAD 50mA/DIV 1.5V OUT I = 1mA LOAD ...

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... LV (Pin 5): VLDO/Linear Regulator Output Pin. This OUT pin provides the regulated output voltage from the VLDO or linear regulator. LV (Pin 6): VLDO/Linear Regulator Input Supply Pin. IN This pin provides the input supply voltage for the VLDO power FET. GND (Pin 7): Analog Ground Pin. Table 1. LTC3541 Control Pin Truth Table PIN NAME OPERATIONAL DESCRIPTION ENBUCK ENVLDO MODE LTC3541 Powered Down Buck Powered Down, VLDO Regulator Powered Down, Linear Regulator ...

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... GND GND PGND 7 11 Figure 1. LTC3541 Functional Block Diagram when using the buck regulator to provide the power for both the VLDO and for external loads. With the ENBUCK pin driven to a logic low and ENVLDO driven to a logic high, the LTC3541 enables the linear regulator, providing a low noise regulated output voltage at the LV OUT from the brought into regulation without the presence OUT of the LV With the ENBUCK and ENVLDO pins both driven to a ...

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... If the input supply voltage is decreased to a value ap- proaching the output voltage, the duty cycle of the buck is increased toward maximum on-time and 100% duty cycle. The output voltage will then be determined by the input voltage minus the voltage drop across the main switch and the inductor. VLDO/Linear Regulator Loop In the LTC3541, the VLDO and linear regulator loops consist of an amplifier and N-channel MOSFET output stages that, when connected with the proper external components, will servo the output to maintain a regulator output volt- age The internal reference voltage provided to the OUT amplifier is 0 ...

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... C To ensure reliable operation and adherence to the load regulation limits presented in the Electrical Characterstics table, the load current must not exceed the linear regulator I limit of 30mA 1ms prior to ENBUCK transitioning to a OUT logic low and thereafer. Further, for configurations that do not use the LTC3541’s buck regulator to provide the VLDO input voltage (LV stable LV voltage no less than 1ms after ENBUCK has IN transitioned to a logic low. due to this transition is a OUT and the load current. Waveforms given of 2.2µF and ...

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... The selection of C the desired buck loop transient response, required effective series resistance (ESR) and burst ripple performance. The LTC3541 minimizes the required number of external components by providing internal loop compensation for the buck regulator loop. Loop stability, transient re- sponse and burst performance can be tailored by choice of output capacitance. For many applications, desirable stability, transient response and ripple performance can LTC3541 VALUE DCR MAX DC (µH) (Ω MAX) CURRENT (A) W × L × H (mm 1.0 0.025 2.0 3.9 × ...

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... The external resistive divider is connected to the output, allowing remote voltage sensing as shown in Figure 6. Checking Transient Response The regulator loop response can be checked by looking at the load transient response. Switching regulators take several cycles to respond to a step in load current. When a load step occurs, V equal to (Δ best, this IN , Figure 6. Setting the LTC3541 Output Voltage       ...

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... OUT The LTC3541 VLDO and linear regulator loops operate at a relatively high gain of –3.5µV/mA and –3.4µV/mA respectively, referred to the LFB input. Thus, a load cur- rent change of 1mA to 300mA produces a 1.05mV drop at the LFB input for the VLDO and a load current change of 1mA to 30mA produces a 0.1mV drop at the LFB input ...

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... Efficiency = 100% – ( ...) where L1, L2, etc. are the individual loss terms as a per- centage of input power. Although all dissipative elements in the circuit produce losses, three main sources typically account for the majority of the losses in the LTC3541 circuits losses and loss across VLDO output device. When operating with both the buck and VLDO active (ENBUCK and ENVLDO equal to logic high), V loss and loss across the VLDO output device dominate the efficiency loss at low load currents, whereas the I loss and loss across the VLDO output device dominate the efficiency loss at medium to high load currents. At ...

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... LOADBUCK (LV For the 3mm × 3mm DFN package, the θ Thus, the junction temperature of the regulator is 85°C + (0.167)(43) = 92°C J which is well below the maximum junction temperature of 125°C. Note that at higher supply voltages, the junction tempera- ture is lower due to reduced switch resistance R LTC3541 • θ given by voltage of 1.8V OUT of the P-channel switch at 85°C is DS(ON) of the N-channel switch DS(ON • R ...

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... LFB node. 5. Keep the (–) plates of C and C IN sible. DESIGN EXAMPLE As a design example, assume the LTC3541 is used in a single lithium-ion battery powered cellular phone ap- plication. The V will be operating from a maximum of IN 4.2V down to about 3V. The load current requirement is a maximum of 0.5A for the buck output but most of the time it will be in standby mode, requiring only 2mA. Ef- ficiency at both low and high load currents is important. ...

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... GND 165k 2V/DIV LFB 576k V OUT2 1.8V OUT 300mA 2.2µF 3541 TA02a 2V/DIV LV 2V/DIV 165k 2V/DIV 576k V OUT2 1.8V 300mA 2.2µF 3541 TA03a LTC3541 V OUT OUT V IN 4ms/DIV I = 200mA VOUT I = 300mA LVOUT V OUT OUT 200mA 4ms/DIV VOUT I = 300mA LVOUT 3541 TA02b ...

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... IN 10µF 73k PGND Dual Output Using Minimal External Components with V Signal, Buck in Burst Mode Operation for High Efficiency Down to Low Load Currents V IN 2.9V TO 4.2V SW ENVLDO MODE V 2.2µH IN ENBUCK LTC3541 22pF 143k V OUT1 BUCKFB 1. 200mA IN 10µF 115k PGND  OUT2 ...

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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 LTC3541 R = 0.115 0.38 ± 0.10 TYP 6 10 ...

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... DC/DC Regulator, 2.25MHz 2 LTC3445 I C Controllable Buck Regulator with Two LDOs and Backup Battery Input LTC3446 Triple Output Step-Down Converter 1A Output Buck, Two Each 300mA VDLOs LTC3448 600mA (I ), High Efficiency, 1.5MHz/2.25MHz OUT Synchronous Step-Down Regulator with LDO Mode LTC3541-2 High Efficiency Buck plus VLDO Regulator LTC3541-3 High Efficiency Buck plus VLDO Regulator LTC3547 Dual 300mA (I ), 2.25MHz, Synchronous OUT Step-Down DC/DC Converter LTC3548/LTC3548-1 Dual 800mA/400mA (I OUT LTC3548-2 Step-Down DC/DC Converter LTC3700 Step-Down DC/DC Controller with LDO Regulator PowerPath is a trademark of Linear Technology Corporation. 0 Linear Technology Corporation 1630 Mccarthy Blvd ...