Datasheet LTC7897 (Analog Devices) - 5

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Data Sheet LTC7897
(Specifications are for TJ = -40°C to +150°C for the minimum and maximum values, TA = 25°C for the typical values, VIN = 12V, RUN = 12V, VPRG = floating, EXTVCC = 0V, DRVSET = 0V, DRVUV = 0V, TGUP = TGDN = TGxx, BGUP = BGDN = BGxx, and DTCA and DTCB = 0V, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS/COMMENTS MIN TYP MAX UNITS
Soft-Start Charge TRACK/SS = 0V 7 9 11 µA Current RUN Pin ON Threshold RUN Rising 1.15 1.20 1.25 V RUN Pin Hysteresis 120 mV OVLO Pin OFF Threshold OVLO OVLO Rising 1.15 1.20 1.25 V OVLO Pin Hysteresis 120 mV
DC Supply Current
VIN Shutdown Current RUN = 0V 1 μA VIN Sleep Mode SENSE− < 3.2V, EXTV Current CC = INTVCC 15 μA Sleep Mode Current
3
VIN Current SENSE− ≥ 3.2V, EXTVCC = INTVCC 5 μA VIN Current SENSE− ≥ 3.2V, EXTVCC ≥ 12V 1 μA EXTVCC Current SENSE− ≥ 3.2V, EXTVCC ≥ 12V 6 μA SENSE− Current SENSE− ≥ 3.2V 10 μA Pulse-Skipping or Forced Continuous 2 mA Mode (FCM), VIN or EXTVCC Current
3 Gate Drivers
DRVSET = INTV TGxx or BGxx CC Pull-up 2.0 On-Resistance Ω Pull-down 1.0 Ω TGxx or BGxx Transition Time
4
Rise Time CLOAD = 3300pF 25 ns Fall Time CLOAD = 3300pF 15 ns TGxx Off to BGxx On DTCA = 0V 50 ns Adaptive Delay Time
4
DTCA = INTVCC 30 ns BGxx Off to TGxx On DTCB = 0V 50 ns Adaptive Delay Time
4
DTCB = INTVCC 30 ns
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Rev. A 5 of 53 Document Outline Features Applications General Description Typical Application TABLE OF CONTENTS Revision History Specifications Absolute Maximum Ratings Pin Configurations and Function Descriptions Block Diagram Typical Performance Characteristics Theory of Operation Main Control Loop Power and Bias Supplies (VIN, EXTVCC, DRVCC, and INTVCC) High-Side Bootstrap Capacitor Dead Time Control (DTCA and DTCB Pins) Start-Up and Shutdown (RUN, OVLO, and TRACK/SS Pins) Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and PhaseLocked Loop (FREQ and PLLIN/SPREAD Pins) Input Supply Overvoltage Lockout (OVLO Pin) Output Overvoltage Protection Foldback Current Power Good 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 Dead Time Control (DTCA and DTCB Pins) DTCX Pins Tied to INTVCC or Ground (Adaptive Dead Time Control) DTCX Pin Connected with a Resistor to GND Power MOSFET Selection CIN and COUT Selection Setting the Output Voltage RUN Pin and Overvoltage/Undervoltage Lockout Soft-Start and Tracking (TRACK/SS Pin) DRVCC and INTVCC Regulators (OPTI-DRIVE) Topside MOSFET Driver Supply (CB, DB) Minimum On-Time Considerations Fault Conditions: Current Limit and Foldback Fault Conditions: Overvoltage Protection Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Design Example PC Board Layout Checklist PC Board Layout Debugging Typical Application Related Parts Outline Dimensions Ordering Guide