LTC3546 Linear Technology, LTC3546 Datasheet
LTC3546
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LTC3546 Summary of contents
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... IN 22μF V FB1 30.1k BMC1 30.1k V TRACK/SS1 IN FREQ I TH1 13k GNDA PGND1 10pF 1000pF 3546 TA01a LTC3546 or 2A/2A Confi gurable ® 3546 is a dual, constant-frequency, synchronous ® operation, pulse V Effi ciency (Burst Mode Operation) OUT2 100 SW1D CONNECTED TO SW2 2.5V 95 OUT 90 ...
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... LTC3546IUFD LTC3546IUFD#TR LTC3546EFE LTC3546EFE#TR LTC3546IFE LTC3546IFE#TR Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ...
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... SW2A/B Externally Connected to SW1D BMC2 = V (Note 8) IN BMC2 = 0.4V (Note 3.6V IN2 V = 3.6V IN2 V = 3.6V IN2 V = 3.6V IN2 V = 3.6V IN1 V = 3.6V IN1 ITH1 RUN1 LTC3546 = 3.6V, unless otherwise specifi ed. (Note 2) CCA MIN TYP = V 2.25 CCD l 0.588 0.6 0.04 l 0.02 l –0.02 1400 0.8 1. 600 400 RUN1 0V, 400 ...
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... The LTC3546I is guaranteed to meet performance specifi cations over the full –40°C to 125°C operating junction temperature range Note 3: The LTC3546 is tested in feedback loop which servos V midpoint for the error amplifi 0.6V) and V ITH1 the error amplifi ...
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... LOAD OUT2 Pulse-Skipping Mode Operation V OUT 20mV/DIV I LOAD 500mA/DIV 3546 G08 1μs/DIV SW1D CONNECTED TO SW2 1.8V OUT I = 200mA LOAD LTC3546 OUT1 Forced Continuous Mode Operation V OUT 20mV/DIV I LOAD 250mA/DIV 3546 G03 1μs/DIV SW1D CONNECTED TO SW1 1.2V OUT I = 100mA LOAD ...
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... LTC3546 TYPICAL PERFORMANCE CHARACTERISTICS OUT2 Burst Mode Operation V OUT 20mV/DIV I LOAD 500mA/DIV www.DataSheet4U.com 1μs/DIV SW1D CONNECTED TO SW1 2.5V OUT I = 300mA LOAD OUT1 Effi ciency vs Load Current 95 SW1D CONNECTED TO SW1 1.8V OUT Burst Mode OPERATION PULSE SKIP 65 FORCED ...
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... SW1D CONNECTED TO SW2 3. 1.8V 86 OUT I = 200mA LOAD 85 3.5 4.0 0.5 1.0 1.5 2.0 2.5 FREQUENCY (MHz) 3546 G26 LTC3546 OUT1 Load Step V OUT 100mV/DIV I LOAD 1A/DIV 2A 100μs/DIV SW1D CONNECTED TO SW1 V = 3.6V IN 4.75 5. 1.2V OUT I = 200mA TO 1.9A LOAD 3546 G21 OUT2 Load Step V OUT 100mV/DIV I LOAD ...
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... LTC3546 TYPICAL PERFORMANCE CHARACTERISTICS OUT2 Effi ciency vs Frequency SW1D CONNECTED TO SW1 87 www.DataSheet4U.com 2.5V 86 OUT I = 400mA LOAD 85 0.5 1.0 1.5 2.0 2.5 3.0 3.5 FREQUENCY (MHz) OUT2 DS(ON) IN 0.080 SW1D CONNECTED TO SW2 T = 27°C A 0.075 0.070 0.065 P-CHANNEL IMP 0.060 0.055 N-CHANNEL IMP ...
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... When PHASE the SW1 regulator and the SW2A/B regulator are switching 180° out-of-phase. I (Pin 19/Pin 22): Error Amplifi er Compensation for TH1 to IN2 Channel 1. Peak current increases with an increase in the voltage on this pin. Nominal voltage range for this pin 1.5V. LTC3546 to IN2 or GND. When disabled, SW1D IN 3546fb 9 ...
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... LTC3546 PIN FUNCTIONS (UFD/FE) V (Pin 20/Pin 23): Feedback voltage from external FB1 resistive divider from Channel 1 output. Nominal voltage for this pin is 0.6V. TRACK/SS1 (Pin 21/Pin 24): Tracking input for Channel 1 output or optional external soft-start input external voltage at this pin. Leaving this pin fl oating allows V to start-up using the internal soft-start ...
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... DEPENDENT SWITCH AUTO DETECT AND CONTROL INTERNAL SOFT-START MUX – 0.63V LOGIC + – + 0.552V – – LIMIT TH I BMC2 TH2 LTC3546 V 1A REGULATOR IN1 + – SLOPE COMPENSATION SW1 ANTI-SHOOT THRU + – – PGND1 + PGOOD1 PHASE OSCILLATOR FREQ V IN1D 1A DEPENDENT SWITCHES ...
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... SW1 output or the SW2A/SW2B output. Internal circuitry auto detects which output SW1D is connected to and controls them accordingly. With this fl exibility, the LTC3546 can be confi gured as either a 2A/2A dual regula- tor (when SW1D is connected to SW1 3A/1A dual regulator (when SW1D is connected to SW2A/SW2B). ...
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... When the BMC pin is pulled to V Burst Mode clamp level is used. For lower output voltage ripple at low currents, pulse- skipping mode can be used. In this mode, the LTC3546 www.DataSheet4U.com continues to switch at constant frequency down to very low currents, where it will eventually begin skipping pulses. ...
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... LTC3546 APPLICATIONS INFORMATION A general LTC3546 application circuit is shown in Figure 7. External component selection is driven by the load require- ment, and begins with the selection of the inductors L1, and L2. Once L1 and L2 are chosen, C can be selected. Operating Frequency Selection of the operating frequency is a trade-off between effi ciency and component size. High frequency operation allows the use of smaller inductor and capacitor values ...
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... Burst Mode Operation Considerations There are two factors that determine the load current at which the LTC3546 enters Burst Mode operation: the inductor value and the BMC pin voltage. The transition from low current operation begins when the peak inductor current falls below a level set by the burst clamp ...
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... LTC3546 APPLICATIONS INFORMATION the maximum RMS current. The RMS current calculation is different if the part is used in-phase or out-of-phase. For in-phase, there are two different equations: V > OUT1 OUT2 I = RMS ( • • • – > ...
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... Ceramic Input and Output Capacitors Higher value, lower cost ceramic capacitors are now becoming available in smaller case sizes. Because the LTC3546 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 line. Shutdown, Soft-Start and Tracking Start-Up www.DataSheet4U.com The LTC3546 start-up works by comparing two inputs, an internal 1.2ms linear soft-start ramp and the TRACK/SS pin. Whichever input is lower in voltage is the controlling voltage used for start-up. The internal start-up ramps to 0.6V in 1.2ms slower start-up is desired, the TRACK/SS pin has a 1.15μ ...
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... Regardless of the mode implemented, the TRACK/SS pin should never be pulled high externally as this will result in excessive current during shutdown. The LTC3546 can smoothly handle starting up into a pre- biased output. The tracking function will pick up from the pre-biased voltage and ramp the output up from there. ...
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... During initial start-up, pulse-skipping mode is forced until the PGOOD pin goes high. www.DataSheet4U.com The LTC3546 can also be synchronized to an external clock signal by the SYNC/MODE pin. An internal phase locked loop locks to the incoming signal to provide for 180° out-of-phase operation as well as correct slope compensation ...
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... IN Thermal Considerations The LTC3546 requires the backplane metal (Pin 29 current results in a well soldered to the PC board. This gives the UFD pack even at age exceptional thermal properties, compared to similar IN packages of this size, making it diffi ...
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... Design Example As a design example, consider using the LTC3546 in a portable application with a Li-Ion battery. The battery provides 2.5A in active mode, and 1mA in standby mode. The other output requires 1.2V at 800mA in active mode, and 500μ ...
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... R3 then equals 600k. A close 1% resistor is 604k. The compensation should be optimized for these com- ponents by examining the load step response but a good place to start for the LTC3546 is with a 13kΩ and 1000pF fi lter on both I and I . The output capacitor may ...
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... IN TRACK/SS2 TRACK/SS1 PHASE I TH2 R ITH2 PGND2 GNDA PGND1 13k C ITH2 1000pF EXPOSED PAD Figure 7. Typical Schematic for 2A/2A Regulator V CC RUN2 PGOOD2 PGOOD1 SYNC/MODE L1 LTC3546 1.0μH SW2A C6 SW2B SW1D 10pF V FB2 FREQ PHASE I TH2 R9 R6 TRACK/SS2 TRACK/SS1 90.9k 5. 0.1μF BMC2 GND BMC1 470pF = 2 ...
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... TRACK/SS2 TRACK/SS1 PHASE I TH2 R ITH2 PGND2 GNDA PGND1 13k C ITH2 1000pF EXPOSED PAD Figure 9. Typical Schematic for 3A/1A Regulator 100 10 1 0.1 0.01 0.001 0.0001 0.1 1 3546 F09b LTC3546 R6 IN2 100k L1 1.2μH V OUT1 SW1 1.8V FF1 100pF RUN1 OUT1 V 22μF FB1 R1 R2 59k 30.1k V ...
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... LTC3546 PACKAGE DESCRIPTION 4.50 ± 0.05 3.10 ± 0.05 2.50 REF 2.65 ± 0.05 www.DataSheet4U.com RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 5.00 ± 0.10 (2 SIDES) NOTE: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WXXX-X). 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4 ...
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... BSC (.020 – .030) 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LTC3546 9.60 – 9.80* (.378 – .386) 4.75 (.187) 28 2726 ...
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