Datasheet LTC7893 (Analog Devices) - 7

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Data Sheet LTC7893
(Specifications are at TJ = -40°C to +125°C for the minimum and maximum values, TA = 25°C for the typical values, VBIAS = 12V, RUN = 5V, VPRG = Floating, EXTVCC = 0V, DRVSET = 0V, DRVUV = 0V, DTCA and DTCB = 0V, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS/COMMENTS MIN TYP MAX UNITS
FREQ = 75kΩ, TA = 25°C 450 500 550 kHz FREQ = 12.4kΩ 3 MHz Synchronizable f Frequency Range SYNC PLLIN/SPREAD = External Clock 0.1 3 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 Outputs
PGOOD Voltage Low PGOOD = 2mA, TA = 25°C 0.2 0.4 V PGOOD Leakage PGOOD = 5V, T Current A = 25°C -1 0 +1 µA TA = 25°C PGOOD Trip Level (VFB VFB Rising 7 10 13 % with Respect to Set Hysteresis 1.6 % Regulated Voltage) VFB Falling -13 -10 -7 % Hysteresis 1.6 % PGOOD Delay for 25 µs Reporting a Fault .1 The LTC7893 is tested in a feedback loop that servos ITH voltage (VITH) to a specified voltage and measures the resultant feedback voltage (VFB). 2 SENSE+ bias current is reflected to the bias supply by the formula I + VBIAS = ISENSE × VBIAS/(VOUT × η), where η is the efficiency. 3 Rise and fall times are measured using 10% and 90% levels. Delay times are measured using 50% levels unless otherwise noted. 4 TGx falling to BGx rising and BGx falling to TGx rising delay times are measured at the rising and falling thresholds on TGx and BGx of approximately 1V. See Figure 40 and Figure 41. 5 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 7 of 48 Document Outline Features Applications General Description Typical Application TABLE OF CONTENTS Revision History Specifications Absolute Maximum Ratings Pin Configurations and Function Descriptions Typical Performance Characteristics Functional diagram 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) Startup and Shutdown (RUN and SS 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) Output Overvoltage Protection 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 Pin Tied to Ground (Adaptive Dead Time Control) DTCx Pin connected with a resistor to GND Power FET Selection CIN and COUT Selection Setting the Output Voltage RUN Pin and Undervoltage Lockout Soft-Start (SS Pin) INTVCC Regulators (OPTI-DRIVE) Topside FET Driver Supply (CB) Minimum On-Time Considerations Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Design Example PCB Board Layout Checklist PCB Layout Debugging Typical Applications Related Parts Outline Dimensions Ordering Guide