Datasheet LTC7818 (Analog Devices) - 5
| Manufacturer | Analog Devices |
| Description | 40V, Low IQ, 3MHz, Triple Output Buck/Buck/Boost Synchronous Controller |
| Pages / Page | 44 / 5 — ELECTRICAL CHARACTERISTICS. The. indicates specifications which apply … |
| Revision | A |
| File Format / Size | PDF / 5.4 Mb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. indicates specifications which apply over the specified operating
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LTC7818
ELECTRICAL CHARACTERISTICS The
l
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
Sleep Mode Current (Note 3) V – SENSE1 ≥ 3.2V Only Channel 1 On VBIAS Current, EXTVCC = 0V 5 9 µA VBIAS Current, EXTVCC = 4.8V 1 4 µA EXTVCC Current, EXTVCC ≥ 4.8V 5 10 µA SENSE1– Current 10 18 µA Sleep Mode Current (Note 3) V – SENSE1 ≥ 3.2V, EXTVCC ≥4.8V All Channels On VBIAS Current 1 4 µA EXTVCC Current 8 14 µA SENSE1– Current 16 26 µA Pulse-Skipping or Forced Continuous Mode One Channel On 1.5 mA VBIAS or EXTVCC Current (Note 3) All Channels On 3 mA
Gate Drivers
TG or BG On-Resistance Pull-up 2.0 Ω Pull-down 1.0 Ω TG or BG Transition Time (Note 6) Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 15 ns TG Off to BG On Delay CLOAD = 3300pF Each Driver Synchronous Switch-On Delay Time Bucks (Channels 1, 2) 15 ns Boost (Channel 3) 15 ns BG Off to TG On Delay CLOAD = 3300pF Each Driver Top Switch-On Delay Time Bucks (Channels 1, 2) 15 ns Boost (Channel 3) 15 ns tON(MIN)1,2 Buck TG Minimum On-Time (Note 7) 40 ns tON(MIN)3 Boost BG Minimum On-Time (Note 7) 80 ns Maximum Duty Factor for TG Bucks (Channels 1,2), FREQ = 0V 98 99 % Boost (Channel 3) in Overvoltage 100 % Maximum Duty Factor for BG Bucks (Channels 1,2) in Overvoltage 100 % Boost (Channel 3), FREQ = 0V 93 % BOOST3 Charge Pump Available VBOOST3 = 16V, VSW3 = 12V, FREQ = 0V, 20 50 µA Output Current Forced Continuous Mode IMON3 Current Monitor Output Voltage V + + – SENSE3 = 12V, VSENSE3 − VSENSE3 = 50mV 1.3 1.4 1.5 V V + + – SENSE3 = 12V, VSENSE3 − VSENSE3 = 15mV 0.6 0.7 0.8 V
INTVCC Low Dropout (LDO) Linear Regulator
INTVCC Regulation Point 4.9 5.1 5.3 V INTVCC Load Regulation ICC = 0mA to 100mA, VBIAS ≥ 6V 1.2 2 % ICC = 0mA to 100mA, VEXTVCC ≥ 6V 1.2 2 % EXTVCC LDO Switchover Voltage EXTVCC Rising 4.5 4.7 4.8 V EXTVCC Switchover Hysteresis 250 mV UVLO Undervoltage Lockout INTVCC Rising l 4.10 4.20 4.35 V INTVCC Falling l 3.75 3.85 4.00 V
Spread Spectrum Oscillator and Phase-Locked Loop
fOSC Low Fixed Frequency VFREQ = 0V, PLLIN/SPREAD = 0V 330 380 430 kHz High Fixed Frequency VFREQ = INTVCC, PLLIN/SPREAD = 0V l 2.0 2.25 2.5 MHz Programmable Frequency RFREQ = 374kΩ, PLLIN/SPREAD = 0V 100 kHz RFREQ = 75kΩ, PLLIN/SPREAD = 0V 450 500 550 kHz RFREQ = 12kΩ, PLLIN/SPREAD = 0V 3 MHz Synchronizable Frequency Range PLLIN/SPREAD = External Clock l 0.1 3 MHz Rev. A For more information www.analog.com 5 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
ELECTRICAL CHARACTERISTICS The
l
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
Sleep Mode Current (Note 3) V – SENSE1 ≥ 3.2V Only Channel 1 On VBIAS Current, EXTVCC = 0V 5 9 µA VBIAS Current, EXTVCC = 4.8V 1 4 µA EXTVCC Current, EXTVCC ≥ 4.8V 5 10 µA SENSE1– Current 10 18 µA Sleep Mode Current (Note 3) V – SENSE1 ≥ 3.2V, EXTVCC ≥4.8V All Channels On VBIAS Current 1 4 µA EXTVCC Current 8 14 µA SENSE1– Current 16 26 µA Pulse-Skipping or Forced Continuous Mode One Channel On 1.5 mA VBIAS or EXTVCC Current (Note 3) All Channels On 3 mA
Gate Drivers
TG or BG On-Resistance Pull-up 2.0 Ω Pull-down 1.0 Ω TG or BG Transition Time (Note 6) Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 15 ns TG Off to BG On Delay CLOAD = 3300pF Each Driver Synchronous Switch-On Delay Time Bucks (Channels 1, 2) 15 ns Boost (Channel 3) 15 ns BG Off to TG On Delay CLOAD = 3300pF Each Driver Top Switch-On Delay Time Bucks (Channels 1, 2) 15 ns Boost (Channel 3) 15 ns tON(MIN)1,2 Buck TG Minimum On-Time (Note 7) 40 ns tON(MIN)3 Boost BG Minimum On-Time (Note 7) 80 ns Maximum Duty Factor for TG Bucks (Channels 1,2), FREQ = 0V 98 99 % Boost (Channel 3) in Overvoltage 100 % Maximum Duty Factor for BG Bucks (Channels 1,2) in Overvoltage 100 % Boost (Channel 3), FREQ = 0V 93 % BOOST3 Charge Pump Available VBOOST3 = 16V, VSW3 = 12V, FREQ = 0V, 20 50 µA Output Current Forced Continuous Mode IMON3 Current Monitor Output Voltage V + + – SENSE3 = 12V, VSENSE3 − VSENSE3 = 50mV 1.3 1.4 1.5 V V + + – SENSE3 = 12V, VSENSE3 − VSENSE3 = 15mV 0.6 0.7 0.8 V
INTVCC Low Dropout (LDO) Linear Regulator
INTVCC Regulation Point 4.9 5.1 5.3 V INTVCC Load Regulation ICC = 0mA to 100mA, VBIAS ≥ 6V 1.2 2 % ICC = 0mA to 100mA, VEXTVCC ≥ 6V 1.2 2 % EXTVCC LDO Switchover Voltage EXTVCC Rising 4.5 4.7 4.8 V EXTVCC Switchover Hysteresis 250 mV UVLO Undervoltage Lockout INTVCC Rising l 4.10 4.20 4.35 V INTVCC Falling l 3.75 3.85 4.00 V
Spread Spectrum Oscillator and Phase-Locked Loop
fOSC Low Fixed Frequency VFREQ = 0V, PLLIN/SPREAD = 0V 330 380 430 kHz High Fixed Frequency VFREQ = INTVCC, PLLIN/SPREAD = 0V l 2.0 2.25 2.5 MHz Programmable Frequency RFREQ = 374kΩ, PLLIN/SPREAD = 0V 100 kHz RFREQ = 75kΩ, PLLIN/SPREAD = 0V 450 500 550 kHz RFREQ = 12kΩ, PLLIN/SPREAD = 0V 3 MHz Synchronizable Frequency Range PLLIN/SPREAD = External Clock l 0.1 3 MHz Rev. A For more information www.analog.com 5 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
