Datasheet LTC7899 (Analog Devices) - 8

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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
PGOOD Delay for 25 Reporting a Fault μs .1 This specification is not tested in production. 2 The LTC7899 is tested in a feedback loop that servos VITH to a specified voltage and measures the resultant VFBB. 3 Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See Applications Information. 4 Rise and fall times are measured using 10% and 90% levels. Delay times are measured using 50% levels. 5 TGxx falling to BGxx rising and BGxx falling to TGxx rising delay times are measured at rising/falling thresholds on TGxx and BGxx of approximately 1.5V. See Figure 37 and Figure 38 . 6 The minimum on-time condition specified for inductor peak-to-peak ripple current is >40% of the maximum load current (IMAX) (see the Minimum On-Time Considerations section).
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Rev. 0 8 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