LTC3547 LINER [Linear Technology], LTC3547 Datasheet
LTC3547
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LTC3547 Summary of contents
Page 1
... All outputs are internally compensated to work with ceramic capacitors. The LTC3547 is available in a low profi le (0.75mm) 3mm × 2mm DFN package. The LTC3547 is also available in a fi xed output voltage confi guration, eliminating the need for the external feedback networks (see Table 2) ...
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... FB1 A LTC3547, –40°C ≤ T ≤ 85°C A LTC3547-1, 0°C ≤ T ≤ 85°C A LTC3547-1, –40°C ≤ T ≤ 85° LTC3547, 0°C ≤ T ≤ 85°C FB2 A LTC3547, –40°C ≤ T ≤ 85°C A LTC3547-1, 0°C ≤ T ≤ 85°C A LTC3547-1, –40°C ≤ T ≤ 85°C ...
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... Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3547E is guaranteed to meet specifi ed performance from 0°C to 85°C. Specifi cations over the –40°C and 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls ...
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... LTC3547 W U TYPICAL PERFOR A CE CHARACTERISTICS Oscillator Frequency vs Temperature 2.6 2 4.2V IN 2.4 2 3. 2.7V IN 2.1 2.0 1.9 1.8 – 50 – 100 TEMPERATURE (°C) 3547 G04 Reference Voltage vs Temperature 612 608 604 600 596 592 588 – – TEMPERATURE (°C) 3547 G07 Effi ciency vs Load Current ...
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... V OUT 1V/DIV I L 200mA/DIV 200µs/DIV 1.8V OUT I = 300mA LOAD OUT COUPLED 100mV/DIV I L 200mA/DIV I LOAD 200mA/DIV 3547 G18 LTC3547 V = 1.8V OUT I = 100mA LOAD 3 3.5 4 4.5 5 5.5 V (V) IN 3547 G14 Load Step OUT COUPLED 100mV/DIV I L 200mA/DIV I LOAD 200mA/DIV 3547 G16 10µ ...
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... LTC3547 CTIO S V (Pin 1): Regulator 1 Output Feedback. Receives FB1 the feedback voltage from the external resistor divider across the regulator 1 output. Nominal voltage for this pin is 0.6V. RUN1 (Pin 2): Regulator 1 Enable. Forcing this pin to V enables regulator 1, while forcing it to GND causes IN regulator 1 to shut down ...
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... P-channel switch increases with decreasing input supply voltage (see Typical Performance Characteristics). Therefore, the user should calculate the worst-case power dissipation when the LTC3547 is used at 100% duty cycle with low input voltage (see Thermal Considerations in the ) is reached. The Applications Information Section). ...
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... The choice of which style inductor to use often depends more on the price vs size requirements, and any radiated fi eld/EMI requirements, decreases than on what the LTC3547 requires to operate. Table 1 L shows some typical surface mount inductors that work IN well in LTC3547 applications. ...
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... ESR make them ideal for switching regulator applications. Because the LTC3547 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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... The resistor divider is chosen such that the V input current is 3µA. For these versions the FB V pin should be connected directly the fi xed output voltages available for the LTC35476-1. Table 2. Fixed Output Voltage Versions PART NUMBER V OUT1 LTC3547 Adjustable LTC3547-1 1 ...
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... Effi ciency = 100% – ( ...) where L1, L2, etc., are the individual losses as a percent- age of input power. Although all dissipative elements in the circuit produce losses, four sources usually account for the losses in LTC3547 circuits quiescent current, 2) switching IN 2 losses losses, 4) other system losses ...
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... J RISE AMBIENT As a worst-case example, consider the case when the LTC3547 is in dropout on both channels at an input volt- age of 2.7V with a load current of 300mA and an ambi- ent temperature of 70°C. From the Typical Performance Characteristics graph of Switch Resistance, the R of the main switch is 0.9Ω. Therefore, power dissipated ...
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... U U APPLICATIO S I FOR ATIO V IN 2.5V TO 5.5V V OUT2 C OUT2 BOLD LINES INDICATE HIGH CURRENT PATHS Figure 2. LTC3547 Layout Diagram (See Board Layout Checklist) VIA TO GND VIA RUN2 V RUN1 IN LTC3547 L2 SW2 SW1 FB2 FB1 R4 GND FB1 ...
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... LTC3547 U U APPLICATIO S I FOR ATIO Design Example As a design example, consider using the LTC3547 in a portable application with a Li-Ion battery. The battery provides a V ranging from 2.8V to 4.2V. The load on IN each channel requires a maximum of 300mA in active mode and 2mA in standby mode. The output voltages are ...
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... I LOAD 200mA/DIV Figure 4c. Transient Response U DDB Package 8-Lead Plastic DFN (3mm × 2mm) (Reference LTC DWG # 05-08-1702 Rev B) 3.00 ±0.10 (2 SIDES) PIN 1 BAR TOP MARK (SEE NOTE 6) 0.200 REF LTC3547 3547 F04c 10µs/DIV 2.5V OUT I = 20mA TO 300mA LOAD R = 0.115 0.40 ± 0.10 TYP ...
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... L1, L2: MURATA LQH32CN4R7M33 1.8V/1.2V Dual 300mA Buck Converter IN C1 4.7µ RUN2 V RUN1 IN 4.7µH 4.7µH SW2 SW1 LTC3547 FB1 FB2 C GND OUT2 4.7µF C1 TAIYO YUDEN JMK316BJ475ML OUT1 OUT2 L1, L2: MURATA LQH32CN4R7M33 COMMENTS 95% Effi ciency <1µA, ThinSOT SD 96% Effi ...