Datasheet LTC7804 (Analog Devices) - 9

LTC7804
TYPICAL PERFORMANCE CHARACTERISTICS EXTVCC Switchover and INTVCC Maximum Current Sense SENSE Pin Input Current Voltage vs T V emperature oltages vs Temperature Threshold vs ITH V Threshold vs ITH V oltage oltage vs VSENSE Voltage SENSE
5.8 60 800 750 5.6 50 PULSE–SKIPPING MODE 700 SENSE+ PIN 5.4 40 650 TAGE (mV) INTV 600 CC Burst Mode 5.2 TAGE (V) 30 OPERATION 550 5.0 500 VOL 20 450 V CC 4.8 EXTVCC RISING 400 10 350 4.6 EXTVCC FALLING 300 OR EXT 0 4.4 250 SENSE CURRENT (µA) V CC 200 4.2 –10 INT 150 4.0 –20 100 FORCED CONTINUOUS MODE MAXIMUM CURRENT SENSE VOL 50 SENSE– PIN 3.8 –30 0 –55 25 5 35 65 95 125 155 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 5 10 15 20 25 30 35 40 TEMPERATURE (°C) ITH VOLTAGE (V) VSENSE COMMON MODE VOLTAGE (V) 7804 G19 7804 G20 7804 G21
SENSE Pin Input Current SENSE Pin Input Current vs ITH Oscillator Frequency vs Temperature Voltage vs Temperature TH
800 800 7 750 750 RFREQ = 374k (100kHz) 6 700 SENSE+ = 12V 700 V R SENSE = 12V FREQ = 75k (500kHz) 650 650 5 RFREQ = 12.5k (3MHz) 600 600 4 RFREQ = GND (375kHz) 550 550 RFREQ = INTVCC (2.25MHz) 3 500 500 450 450 2 400 400 1 350 350 0 300 300 SENSE– PIN 250 SENSE– PIN –1 SENSE CURRENT (µA) 250 200 SENSE CURRENT (µA) 200 SENSE+ < 2.9V –2 SENSE+ < 2.9V 150 150 CHANGE IN FREQUENCY (%) –3 100 SENSE+ = 3.2V 100 50 SENSE+ = 3.2V 50 –4 0 0 –5 –55 –25 5 35 65 95 125 155 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 –55 –25 5 35 65 95 125 155 TEMPERATURE (°C) ITH VOLTAGE (V) TEMPERATURE (°C) 7804 G22 7804 G23 7804 G24
Charge Pump Charging Current Charge Pump Charging Current vs Operating Frequency vs Switch Voltage Output Voltage Noise Spectrum
100 100 0 VSW = 12V VBOOST – VSW = 4V FIGURE 12 CIRCUIT VBOOST – VSW = 4V 90 –10 V 90 IN = 18V, VOUT = 24V DETECTOR = PEAK–HOLD T = 155°C 80 –20 FREQ = GND RBW = 5.1kHz 80 70 –30 PLLIN/SPREAD = GND T = 25°C 70 60 –40 FREQ = INTVCC 50 –50 PLLIN/SPREAD = INTVCC 60 T = –55°C 40 –60 50 30 AMPLITUDE (dBm) –70 20 –80 40 10 –90 CHARGE PUMP CHARGING CURRENT (µA) CHARGE PUMP CHARGING CURRENT (µA) 30 0 –100 0 600 1200 1800 2400 3000 0 5 10 15 20 25 30 35 40 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 OPERATING FREQUENCY (kHz) SWITCH VOLTAGE (V) FREQUENCY (MHz) 7804 G25 7804 G26 7804 G27 Rev. 0 For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Main Control Loop INTVCC/EXTVCC Power Boost Supply and Dropout (BOOST and SW Pins) Shutdown and Start-Up (RUN, SS Pins) Light Load Current Operation: Burst Mode Operation, Pulse-Skipping or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum and Phase-Locked-Loop (FREQ and PLLIN/SPREAD Pins) Operation When VIN > VOUT Operation at Low Input Voltage BOOST Supply Refresh and Internal Charge Pump Applications Information SENSE+ and SENSE– Pins Low Value Resistor Current Sensing Inductor DCR Sensing Inductor Value Calculation Inductor Core Selection Power MOSFET Selection CIN and COUT Selection Setting Output Voltage RUN Pin Soft-Start (SS Pin) INTVCC Regulators Topside MOSFET Driver Supply (CB, DB) Phase-Locked Loop and Frequency Synchronization Setting the Operating Frequency Selecting the Light-Load Operating Mode Minimum On-Time Considerations Fault Conditions: Overtemperature Protection Efficiency Considerations Checking Transient Response Design Example PC Board Layout Checklist PC Board Layout Debugging Package Description Typical Application Related Parts