Datasheet LTC7899 (Analog Devices) - 7

Data Sheet LTC7899
(Specifications are for TJ = -40°C to +150°C for the minimum and maximum values, TA = 25°C for the typical values, all voltages are with respect to V - - IN unless otherwise noted. (GND to VIN ) = 12V, RUN = 5V, EXTVCC = INTVCC, 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
EXTVCC LDO DRVUV = INTVCC, TA = 25°C 7.5 7.7 8.0 V Switchover Voltage DRVUV = floating, TA = 25°C 5.9 6.1 6.4 V EXTVCC Rising DRVUV = 0V, TA = 25°C 4.6 4.8 5.1 V EXTVCC Switchover Hysteresis 250 mV EXTVCC Falling INTVCC Regulation 4.5 V Point
Spread Spectrum Oscillator and Phase-Locked Loop
PLLIN/SPREAD = 0V FREQ = 0V, TA = 25°C 320 370 420 kHz FREQ = INTV 2.0 2.25 2.5 MHz Fixed Frequency f CC OSC FREQ = 374kΩ 100 kHz FREQ = 75kΩ, TA = 25°C 450 500 550 kHz FREQ = 14.7kΩ 2.5 MHz Synchronizable f Frequency Range SYNC PLLIN/SPREAD = External Clock 0.1 2.5 MHz PLLIN Input High Level 2.2 V PLLIN Input Low Level 0.5 V Spread Spectrum PLLIN/SPREAD = INTVCC Frequency Range Minimum Frequency 0 % (Relative to fOSC) Maximum Frequency 20 %
PGOOD Output
PGOOD Voltage Low IPGOOD = 2mA, TA = 25°C 0.2 0.4 V PGOOD Leakage PGOOD = 5V, T Current A = 25°C -1 +1 μA TA = 25°C PGOOD Trip Level VFBB VFBB Rising 7 10 13 % with Respect to Set Hysteresis 2.5 % Regulated Voltage VFBB Falling -13 -10 -7 % Hysteresis 2.5 %
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Rev. 0 7 of 50 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 (VBIAS, EXTVCC, DRVCC, and INTVCC) High-Side Bootstrap Capacitor Dead Time Control (DTCA and DTCB Pins) Start-Up and Shutdown (RUN and SS Pins) Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) PolyPhase Applications (CLKOUT and PHASMD Pins) Output Overvoltage Protection Operation at Low Input Voltage BOOST Supply Refresh 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 VIN- (Adaptive Dead Time Control) DTCx pin connected with a resistor to VIN-: Power MOSFET Selection CIN and COUT Selection Setting the Output Voltage RUN Pin and Undervoltage Lockout Soft-Start (SS Pin) DRVCC and INTVCC Regulators (OPTI-DRIVE) Topside MOSFET Driver Supply (CB, DB) Minimum On-Time Considerations 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