Datasheet LTC7899 (Analog Devices)

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Data Sheet LTC7899
140V, Low IQ, Negative to Positive Synchronous Boost Controller with 10V Gate Drive
FEATURES GENERAL DESCRIPTION
 Converts Negative Input to Positive Output The LTC®7899 is a high performance DC/DC negative to Regulated with Respect to Ground positive switching regulator controller that drives all N-  Wide |V - channel synchronous MOSFET stages and can operate IN |+VOUT Range: 4V to 135V (140V ABS MAX)  Internal Feedback Level Shifter for Easy Output from input voltages up to 135V. The positive output Voltage Programming with Two Resistors voltage can easily be programmed with only two resistors by using the integrated feedback level shifter.  Adjustable Gate Drive Level: 5V to 10V (OPTI-DRIVE, The LTC7899 can alternatively be configured as a step- 14V ABS MAX) up (Boost) operation with pass-through.  Adjustable Driver Voltage UVLO  Adaptive or Resistor-Adjustable Dead Times The gate drive voltage for the LTC7899 can be pro-  Split-Output Gate Drivers for Adjustable Turn-On grammed from 5V to 10V to allow the use of logic or and Turn-Off Driver Strengths standard-level MOSFETs to maximize efficiency.  Supports Positive Input to Positive Output Boost Up The low no-load quiescent current extends operating to 135V with Pass-Through run time in battery-powered systems. OPTI-LOOP®  Operation Down to 1V after Start-Up compensation allows the transient response to be  CLK Output for High Power PolyPhase Operation optimized over a wide range of output capacitance and  Spread Spectrum Frequency Modulation ESR values. The user can adjust the dead times of the  Programmable Frequency (100kHz to 2.5MHz) LTC7899 with external resistors for margin or to tailor  Phase-Lockable Frequency (100kHz to 2.5MHz) the application for higher efficiency and allow for high  28-Pin (4mm x 5mm) QFN Package frequency operation. The LTC7899 additionally features spread spectrum
APPLICATIONS
operation, which significantly reduces the peak  Industrial Power Systems radiated and conducted noise on both the input and output supplies, making it easier to comply with  Military/Avionics electromagnetic interference (EMI) standards.  Telecommunications Power Systems
TYPICAL APPLICATION 2mΩ 15µH VOUT 100 48V 56µF DRV 10µF 68µF 10µF CC UP TO 8.8A 99 ×4 ×4 ×4 ×3 RUN V – BIAS SENSE+ SENSE– VIN BOOST 98 –32V TO –54V 0.1µF 0.22µF 97 CLKOUT SW ×4 ) PGOOD LTC7899 V – (% 96 IN PHASMD Y BGUP C 249kΩ PLLIN/SPREAD BGDN FREQ 95 ENI MODE CI V – F 94 20kΩ IN ILIM TGUP DTCA EF 402kΩ TGDN 93 DTCB 21kΩ VFBA DRVUV BURST MODE VFBB 92 DRVSET f ITH SW = 150kHz EXTVCC SS V 91 OUT = +48V – 15nF INTV 10kΩ CC DRVCC VIN VIN– = –48V 0.1µF 470pF 90 0.1µF 4.7µF 10kΩ 0.01 0.1 1 9
001
LOAD CURRENT (A)
002
Figure 1. High Power -48V Input to 48V Output Converter Figure 2. VOUT Efficiency for Figure 1
Rev. 0 DOCUMENT FEEDBACK
TECHNICAL SUPPORT
One Analog Wa y, Wilmington, MA 01887 -2356, U.S.A. Tel: 781.329.47 00 ©2025 A n a l o g D e v i c e s , I n c . A l l r i g h t s r e s e r v e d . 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