Datasheet LTC7810 (Analog Devices) - 8

LTC7810
TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage Frequency Spectrum Output Voltage Frequency Spectrum Oscillator Frequency (Spread Spectrum Disabled) (Spread Spectrum Enabled) vs Temperature
0 0 700 FIGURE 15 CIRCUIT FIGURE 15 CIRCUIT RFREQ = 30k –10 f –10 SW = 600kHz fSW = 600kHz RFREQ = 70k 600 VOUT = 3.3V VOUT = 3.3V FREQ = 0V –20 –20 PLLIN/SPREAD = GND PLLIN/SPREAD = INTVCC FREQ = INTVCC –30 R –30 R 500 BW = 5.1kHz BW = 5.1kHz –40 –40 400 –50 –50 300 –60 –60 AMPLITUDE (dBm) AMPLITUDE (dBm) FREQUENCY (kHz) –70 –70 200 –80 –80 100 –90 –90 –100 –100 0 200 400 600 800 1000 1200 1400 200 400 600 800 1000 1200 1400 –55 –25 5 35 65 95 125 155 FREQUENCY (kHz) FREQUENCY (kHz) TEMPERATURE (°C) 7810 G10 7810 G11 7810 G12
BOOST Charge Pump Output BOOST Charge Pump Output BOOST Charge Pump Output Current vs Frequency Voltage in Dropout vs Input Voltage Current in Dropout vs Input Voltage
140 11.0 160 OUTPUT IN DROPOUT OUTPUT IN DROPOUT OUTPUT IN DROPOUT VIN = VSW = VSENSE– = 12V 120 10.5 VIN = VSW = VSENSE– 140 VIN = VSW = VSENSE– FREQ = GND FREQ = GND 100 10.0 120 9.5 100 80 (V) SW 9.0 80 60 – V 8.5 60 40 V BOOST 8.0 40 CHARGE PUMP CURRENT (µA) Normal Dropout, V V BOOST – VSW = 4V BOOST – VSW = 4V CHARGE PUMP CURRENT (µA) 20 Normal Dropout, V V BOOST – VSW = 7V BOOST – VSW = 7V 7.5 NORMAL DROPOUT 20 Low I V Q Dropout, VBOOST – VSW = 4V BOOST – VSW = 7V, LOW IQ DROPOUT LOW IQ DROPOUT Low I 0 Q Dropout, VBOOST – VSW = 7V 7.0 0 0 100 200 300 400 500 600 700 800 900 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 FREQUENCY (kHz) INPUT VOLTAGE (V) INPUT VOLTAGE (V) 7810 G13 7810 G14 7810 G15
SENSE Pins Total Input Maximum Current Sense Current vs VSENSE Voltage Threshold vs ITH Voltage Foldback Current Limit
700 100 100 CHANNEL 1 PULSE–SKIPPING CHANNEL 2 90 600 FORCED CONTINUOUS 80 BURST MODE (MODE=0V) 80 BURST MODE (MODE=1V) 500 60 70 400 40 60 50 300 20 40 SENSE CURRENT (µA) 200 0 30 20 100 –20 10 0 MAXIMUM CURRENT SENSE THRESHOLD (mV) –40 MAXIMUM CURRENT SENSE THRESHOLD (mV) 0 0 10 20 30 40 50 60 70 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 VSENSE COMMON MODE VOLTAGE (V) ITH VOLTAGE (V) VFB VOLTAGE (V) 7810 G16 7810 G17 7810 G18 Rev. A 8 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Main Control Loop Power and Bias Supplies (VIN, NDRV, EXTVCC, DRVCC, REGSD) Boost Supply and Dropout (BOOST and SW pins) Start-Up and Shutdown (RUN, TRACK/SS, OVLO Pins) Light Load 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) Applications Information Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Sensing Setting the Operating Frequency Selecting the Light-Load Operating Mode Inductor Value Calculation Inductor Core Selection Power MOSFET Selection CIN and COUT Selection Setting the Output Voltage RUN Pins and Overvoltage/Undervoltage Lockout Tracking and Soft-Start (TRACK/SS1, TRACK/SS2 Pins) Single Output Two-Phase Operation DRVCC Regulators Topside MOSFET Driver Supply (CB, DB) Burst Clamp Programming Fault Conditions: Current Limit and Current Foldback Fault Conditions: Overvoltage Protection (Crowbar) Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Minimum On-Time Considerations Efficiency Considerations Checking Transient Response Design Example PC Board Layout Checklist PC Board Layout Debugging Typical Applications Package Description Revision History Typical Application Related Parts