Datasheet LTC7818 (Analog Devices) - 4

LTC7818
ELECTRICAL CHARACTERISTICS The
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indicates specifications which apply over the specified operating junction temperature range, otherwise specifications are for TA = 25°C, VBIAS = 12V, RUN1,2,3 > 1.25V, EXTVCC = 0V, VPRG3 = FLOAT unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Input Supply (VBIAS, VIN)
VBIAS Bias Input Supply Operating Voltage Range 4.5 40 V VIN Boost Converter Input Supply Operating VBIAS ≥ 4.5V 1 40 V Range IQ VIN Current in Regulation Front Page Circuit, 14V to 3.3V, No Load, 14 µA RUN2,3 = 0V
Controller Operation
VOUT1,2 Buck Output Voltage Operating Range 0.8 40 V VOUT3 Boost Output Voltage Operating Range 40 V VFB1,2 Buck Regulated Feedback Voltage (Note 4) VBIAS = 4.5V to 40V, ITH1,2 Voltage = 0.6V to 1.2V l 0.788 0.800 0.812 V 0ºC to 85ºC, All Grades 0.792 0.800 0.808 V VFB3 Boost Regulated Feedback Voltage (Note 4) VBIAS = 4.5V to 40V, ITH3 Voltage = 0.6V to 1.2V, VPRG3 = FLOAT l 1.177 1.195 1.213 V VPRG3 = 0V l 7.81 8.00 8.13 V VPRG3 = INTVCC l 9.77 10.0 10.17 V Buck Feedback Current (Note 4) ±5 ±50 nA Boost Feedback Current (Note 4) VPRG3 = FLOAT ±5 ±50 nA RUN3 = 0V, VPRG3 = 0V or INTVCC ±5 ±50 nA RUN3 = 2V, VPRG3 = 0V or INTVCC 1 µA Buck Feedback Overvoltage Protection Measured at VFB1,2 Relative to 7 10 13 % Threshold Regulated VFB1,2 gm1,2,3 Transconductance Amplifier gm (Note 4) ITH1,2,3 = 1.2V, Sink/Source = 5μA 1.8 mmho V – SENSE(MAX) Maximum Current Sense Threshold VFB1,2 = 0.7V, VSENSE1,2 = 3.3V l 45 50 55 mV V + FB3 = 1.1V, VSENSE3 = 12V Matching for Channels 1& 2 V – SENSE1,2 = 3.3V, VFB2 = INTVCC –3.5 0 3.5 mV I + + SENSE1,2 SENSE1,2+ Pin Current VSENSE1,2 = 3.3V ±1 µA I – – SENSE3 SENSE3– Pin Current VSENSE3 = 12V ±1 µA I – SENSE1– SENSE1– Pin Current VSENSE1 ≤ 2.7V 2 µA 3.2V ≤ V – SENSE1 < INTVCC – 0.5V 40 µA V – SENSE1 > INTVCC + 0.5V 660 µA I – SENSE2– SENSE2– Pin Current VSENSE2 = 3.3V ±2 µA V – SENSE2 > INTVCC + 0.5V 620 µA I + + SENSE3 SENSE3+ Pin Current VSENSE3 = 3.3V ±2 µA V + SENSE3 > INTVCC + 0.5V 660 µA Soft-Start Charge Current VTRACK/SS1,2 = 0V, VSS3 = 0V 10 12.5 15 µA RUN Pin ON Threshold VRUN1,2,3 Rising l 1.15 1.20 1.25 V RUN Pin Hysteresis VRUN1,2,3 Falling 100 mV
DC Supply Current (Note 5)
VBIAS Shutdown Current RUN1, 2, 3 = 0V 1.5 µA V – BIAS Sleep Mode Current VSENSE1 < 3.2V, EXTVCC = 0V One Channel On 15 24 µA All Channels On 18 30 µA Rev. A 4 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 (VBIAS, EXTVCC, and INTVCC) Shutdown and Start-Up (RUN1, RUN2, RUN3 and TRACK/SS1, TRACK/SS2, SS3 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) Boost Controller Operation When VIN > VOUT Boost Controller at Low Input Voltage Buck Controller Output Overvoltage Protection Buck Foldback Current Channel 1 Power Good (PGOOD1) Boost Overvoltage Indicator (OV3) Applications Information Inductor Value Calculation Inductor Core Selection Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Current Sensing Setting the Operating Frequency Selecting the Light-Load Operating Mode Power MOSFET Selection Boost CIN and COUT Selection Buck CIN and COUT Selection Setting the Buck Output Voltage Setting Boost Output Voltage (VPRG3 Pin) RUN Pins and Undervoltage Lockout Soft-Start and Tracking (TRACK/SS1, TRACK/SS2, SS3 Pins) Single Output Two-Phase Operation INTVCC Regulators Topside MOSFET Driver Supply (CB, DB) Minimum On-Time Considerations Boost Channel Current Monitor (IMON3) Fault Conditions: Buck Current Limit and Foldback Fault Conditions: Buck Overvoltage Protection (Crowbar) Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Buck Design Example PC Board Layout Checklist PC Board Layout Debugging Typical Applications Package Description Revision History Typical Application Related Parts