Datasheet LTC3871, LTC3871-1 (Analog Devices)

LTC3871/LTC3871-1 Bidirectional PolyPhase Synchronous Buck or Boost Controller
FEATURES DESCRIPTION
n
Unique Architecture Allows Dynamic Regulation of
The LTC®3871/LTC3871-1 is a high performance bidi-
Input Voltage, Output Voltage or Current
rectional buck or boost switching regulator controller n
VHIGH Voltages Up to 100V
that operates in either buck or boost mode on demand. n
VLOW Voltages Up to 30V
It regulates in buck mode from VHIGH-to-VLOW and boost n
Synchronous Rectification: Up to 97% Efficiency
mode from VLOW-to-VHIGH depending on a control signal, n
ADI-Proprietary Advanced Current Mode Control
making it ideal for 48V/12V automotive dual battery sys- n
±1% Voltage Regulation Accuracy Over Temperature
tems. An accurate current programming loop regulates n
Accurate, Programmable Output Current Monitoring
the maximum current that can be delivered in either direc-
and Regulation for Both Buck and Boost Operation
tion. The LTC3871/LTC3871-1 allows both batteries to n
Selectable Buck and Boost Current Sense Limits
supply energy to the load simultaneously by converting n Programmable DRVCC/EXTVCC Optimizes Efficiency energy from one battery to the other. n Programmable VHIGH UV and OV Thresholds Its proprietary constant-frequency current mode n Programmable VLOW OV Threshold architecture enhances the signal-to-noise ratio enabling n Phase-Lockable Frequency: 60kHz to 460kHz low noise operation and provides excellent current n Multiphase/Multi-ICs Operation Up to 12 Phases matching between phases. Additional features include n Selectable CCM/DCM Modes discontinuous or continuous mode of operation, OV/UV n Thermally Enhanced 48-Lead LQFP Package monitors, independent loop compensation for buck and boost operation, accurate output current monitoring and
APPLICATIONS
overcurrent protection. The LTC3871 and LTC3871-1 n Automotive 48V/12V Dual Battery Systems have different current limit foldback characteristics. n Backup Power Systems All registered trademarks and trademarks are the property of their respective owners.
TYPICAL APPLICATION High Efficiency Bidirectional Charger/Power Supply
VHIGH 26V TO 58V OV TE HIGH
Buck-to-Boost Transition
EXTVCC UVHIGH PGA V HIGH VFBLOW BUCK BUCK BOOST ITH SNS1– HIGH SNSD1+ VLOW SNSA1+ 5V/DIV ITH BST1 DRVCC I LOW L LTC3871/ 5A/DIV SS TG1 LTC3871-1 V SW1 V HIGH LOW 12V 10V/DIV BG1 BUCK BOOST BUCK BATTERY SW VFBHIGH 50V/DIV IMON SNS2– 3871 TA01b FREQ SNSD2+ 50μ/DIV VLOW SNSA2+ BST2 DRVCC OVLOW TG2 DRVCC SW2 V5 SGND PGND BG2
PINS NOT SHOWN IN THIS CIRCUIT:
3871 TA01a CLKOUT, DRVSET, FAULT, ILIM, MODE, PHSMD, RUN, SETCUR AND SYNC. Rev. B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts