Datasheet LTC3785 (Analog Devices) - 5
| Fabricante | Analog Devices |
| Descripción | 10V, High Efficiency, Synchronous, No RSENSE Buck-Boost Controller |
| Páginas / Página | 20 / 5 — TA = 25°C, unless otherwise noted. Normalized Oscillator Frequency. VFB … |
| Formato / tamaño de archivo | PDF / 287 Kb |
| Idioma del documento | Inglés |
TA = 25°C, unless otherwise noted. Normalized Oscillator Frequency. VFB vs Temperature. vs Temperature
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LTC3785 Typical perForMance characTerisTics
TA = 25°C, unless otherwise noted. Normalized Oscillator Frequency VFB vs Temperature vs Temperature Oscillator Frequency vs RT
1.2255 1.0 1200 1.2250 0.8 1000 0.6 1.2245 0.4 800 1.2240 0.2 (V) 1.2235 0 600 V FB 1.2230 –0.2 400 –0.4 1.2225 CHANGE FROM 25°C (%) –0.6 OSCILLATOR FREQUENCY (kHz) 200 1.2220 –0.8 1.2215 –1.0 0 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 20 40 60 80 100 TEMPERATURE (°C) TEMPERATURE (°C) RT (kΩ) 3785 G07 3785 G08 3785 G09
VIN Start-Up Voltage VIN Burst Quiescent Current OV and UV Thresholds vs Temperature vs Temperature vs Temperature
2.490 100 12 10 2.485 8 OV THRESHOLD 95 6 µA) 2.480 4 90 2 2.475 CURRENT ( 0 THRESHOLD (%) START-UP VOLTAGE (V) V IN –2 V IN 85 2.470 –4 UV THRESHOLD –6 2.465 80 –8 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 3785 G10 3785 G11 3785 G12 pin FuncTions
RUN/SS (Pin 1):
Run Control and Soft-Start Input. An
VC (Pin 2):
Error Amp Output. A frequency compensa- internal 1µA charges the soft-start capacitor and will tion network is connected from this pin to the FB pin to charge to approximately 2.5V. During a current limit fault, compensate the loop. See Closing the Feedback Loop in the soft-start capacitor will incrementally discharge. Once the Applications Information section for guidelines. the pin drops below 1.225V the IC will enter fault mode,
FB (Pin 3):
Feedback Pin. Connect resistor divider tap turning off the outputs for 32 times the soft-start time. If here. The feedback reference voltage is typically 1.225V >5µA (at RUN/SS = 1.225V) is applied externally, the part The output voltage can be adjusted from 2.7V to 10V ac- will latch off after a fault is detected. If >40µA (at RUN/SS cording to the following formula: = 1.225V) is applied externally, current limit faults will not discharge the SS capacitor. R1+R2 V OUT = 1.225V • R2 3785fc Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Package Description Revision History Typical Application Related Parts
TA = 25°C, unless otherwise noted. Normalized Oscillator Frequency VFB vs Temperature vs Temperature Oscillator Frequency vs RT
1.2255 1.0 1200 1.2250 0.8 1000 0.6 1.2245 0.4 800 1.2240 0.2 (V) 1.2235 0 600 V FB 1.2230 –0.2 400 –0.4 1.2225 CHANGE FROM 25°C (%) –0.6 OSCILLATOR FREQUENCY (kHz) 200 1.2220 –0.8 1.2215 –1.0 0 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 20 40 60 80 100 TEMPERATURE (°C) TEMPERATURE (°C) RT (kΩ) 3785 G07 3785 G08 3785 G09
VIN Start-Up Voltage VIN Burst Quiescent Current OV and UV Thresholds vs Temperature vs Temperature vs Temperature
2.490 100 12 10 2.485 8 OV THRESHOLD 95 6 µA) 2.480 4 90 2 2.475 CURRENT ( 0 THRESHOLD (%) START-UP VOLTAGE (V) V IN –2 V IN 85 2.470 –4 UV THRESHOLD –6 2.465 80 –8 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 3785 G10 3785 G11 3785 G12 pin FuncTions
RUN/SS (Pin 1):
Run Control and Soft-Start Input. An
VC (Pin 2):
Error Amp Output. A frequency compensa- internal 1µA charges the soft-start capacitor and will tion network is connected from this pin to the FB pin to charge to approximately 2.5V. During a current limit fault, compensate the loop. See Closing the Feedback Loop in the soft-start capacitor will incrementally discharge. Once the Applications Information section for guidelines. the pin drops below 1.225V the IC will enter fault mode,
FB (Pin 3):
Feedback Pin. Connect resistor divider tap turning off the outputs for 32 times the soft-start time. If here. The feedback reference voltage is typically 1.225V >5µA (at RUN/SS = 1.225V) is applied externally, the part The output voltage can be adjusted from 2.7V to 10V ac- will latch off after a fault is detected. If >40µA (at RUN/SS cording to the following formula: = 1.225V) is applied externally, current limit faults will not discharge the SS capacitor. R1+R2 V OUT = 1.225V • R2 3785fc Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Package Description Revision History Typical Application Related Parts