Datasheet LTC7890 (Analog Devices) - 5

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LTC7890 SPECIFICATIONS Table 1. Electrical Characteristics (Continued) Parameter Symbol Test Conditions/Comments Min Typ Max Unit
SPREAD SPECTRUM OSCILLATOR AND PHASE- LOCKED LOOP (PLL) Fixed Frequency fOSC PLLIN/SPREAD = 0 V Low Fixed Frequency FREQ = 0 V, TA = 25°C 320 370 420 kHz High Fixed Frequency FREQ = INTVCC 2.0 2.25 2.5 MHz Programmable Frequency FREQ = 374 kΩ 100 kHz FREQ = 75 kΩ, TA = 25°C 450 500 550 kHz FREQ = 12.5 kΩ 3 MHz Synchronizable Frequency Range fSYNC PLLIN/SPREAD = external clock 0.1 3 MHz PLLIN Input High Level 2.2 V PLLIN Input Low Level 0.5 V Spread Spectrum Frequency Range (Relative to fOSC) PLLIN/SPREAD = INTVCC Minimum Frequency 0 % Maximum Frequency 20 % PGOODx OUTPUTS PGOODx Voltage Low PGOODx = 2 mA, TA = 25°C 0.2 0.4 V PGOODx Leakage Current PGOODx = 5 V, TA = 25°C ±1 µA PGOODx Trip Level (VFBx with Respect to Set TA = 25°C Regulated Voltage) % VFBx Rising 7 10 13 Hysteresis 1.6 % VFBx Falling –13 –10 –7 % Hysteresis 1.6 % PGOODx Delay for Reporting a Fault 25 μs 1 This specification is not tested in production. 2 The LTC7890 is tested in a feedback loop that servos ITHx voltage (VITHx) to a specified voltage and measures the resultant feedback voltage (VFBx). 3 SENSE1– bias current is reflected to the input supply by the formula IVIN = ISENSE1– × VOUT1/(VIN × η), where η is the efficiency. 4 Rise and fall times are measured using 10% and 90% levels. Delay times are measured using 50% levels. 5 SWx falling to BGxxx rising and BGxxx falling to SWx rising delay times are measured at the rising and falling thresholds on SWx and BGxxx of approximately 1 V. See Figure 41 and Figure 42. 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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Document Outline Features Applications Typical Application Circuit General Description Specifications Electrical Characteristics Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Theory of Operation Functional Diagram Main Control Loop Power and Bias Supplies (VIN, EXTVCC, DRVCC, and INTVCC) High-Side Bootstrap Capacitor Dead Time Control (DTCA and DTCB Pins) Startup and Shutdown (RUNx and TRACK/SSx 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) 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 GND (Adaptive Dead Time Control) DTCx Pins Tied to INTVCC (Smart Near Zero Dead Time Control) DTCx Pins Connected with a Resistor to GND Power FET Selection CIN and COUT Selection Setting the Output Voltage RUNx Pins and Undervoltage Lockout Soft Start and Tracking (TRACK/SSx Pin) 2-Phase Single Output Operation INTVCC Regulators (OPTI-DRIVE) Topside FET Driver Supply (CB) 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 PCB Layout Checklist PCB Layout Debugging Typical Applications Related Products Outline Dimensions Ordering Guide Evaluation Boards