Features and Benefits
- Unique Architecture Allows Dynamic Regulation of Input Voltage, Output Voltage or Current
- Operates with External Gate Drivers and MOSFETs
- VHIGH Voltages Up to 100V; VLOW Voltages Up to 60V
- Synchronous Rectification: Up to 98% Efficiency
- ADI-Proprietary Advanced Current Mode Control
- ±1% Voltage Regulation Accuracy Overtemperature
- Accurate, Programmable Inductor Current Monitoring and Bidirectional Regulation
- SPI Compliant Serial Interface
- Operation Status and Fault Report
- Programmable VHIGH, VLOW Margining
- Phase-Lockable Frequency: 60kHz to 750kHz
- Optional Spread Spectrum Modulation
- Multiphase/Multi-ICs Operation Up to 24 Phases
- Selectable CCM/DCM/Burst Mode Operation
- Thermally Enhanced 64-Lead LQFP Package
- AEC-Q100 Qualification in Progress
The LTC7871 is a high performance bidirectional buck or boost switching regulator controller that operates in either buck or boost mode on demand. It regulates in buck mode from VHIGH-to-VLOW and boost mode from VLOW-to-VHIGH depending on a control signal, making it ideal for 48V/12V automotive dual battery systems. An accurate current programming loop regulates the maximum current that can be delivered in either direction. The LTC7871 allows both batteries to supply energy to the load simultaneously by driving energy from either battery to the other.
Its proprietary constant frequency current mode architecture enhances the signal-to-noise ratio enabling low noise operation and provides excellent current matching between phases. Additional features include an SPI-compliant serial interface, discontinuous or continuous mode of operation, OV/UV monitors, independent loop compensation for buck and boost operation, accurate inductor current monitoring and overcurrent protection.
The LTC7871 is available in a 64 pin 10mm × 10mm LWE package.
- Automotive 48V/12V Dual Battery Systems
- Backup Power Systems
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (1)
Demonstration circuit DC2886A is a high power, high efficiency six-phase bidirectional converter featuring the LTC7871 and LTC7060. The terminals labeled VHIGH and VLOW are either inputs or outputs depending on the direction of power flow. When the switch at SW1 is in the BUCK position, VLOW provides a 14V output and VHIGH is the input with a range of 30V to 70V. When the switch is in the BOOST position, VHIGH provides a 48V output and VLOW is the input with a range of 10V to 14V. The maximum VLOW current is 180A in both directions. The maximum output power is 2.5kW when operating as a buck within the input voltage range. When operating as a boost, the maximum output power is 2.4kW when the input voltage is 14V. External airflow is required when operating at maximum power. The MOSFETs in each phase are driven by the LTC7060 half bridge driver. Each LTC7060 gate driver is placed next to the MOSFETs and receives a PWM signal from the LTC7871.
The inductor current for each phase is sensed with a low 1mΩ sense resistor using a highly accurate AC/DC current sensing architecture with low power dissipation. The LTC7871’s constant-current loop provides a DC current limit for the current flowing in or out of the VLOW terminal depending on the state of the BUCK pin. This current can be programmed with the SETCUR pin and monitored with the IMON pin.
The DC2886A provides a SPI compatible serial port. With a DC2026C (Linduino® One) demo board and QuikEval™ software on a host computer, the user can:
- Margin the regulated VLOW or VHIGH up or down.
- Margin the DC current limit up or down with the SETCUR pin.
- Adjust the frequency spread and modulation rate of the spread spectrum circuit, when spread spectrum is enabled.
- Monitor the operational status and faults of the LTC7871.
Additional features of the DC2886A include:
- Pin selectable light load operating modes
- Buck: FCM, pulse-skipping and Burst Mode® Operation
- Boost: FCM and pulse-skipping
- SYNC and CLKOUT pins
- Optional jumper to enable spread spectrum modulation
- RUN, FAULT, PGOOD and PWNEN pins
- BUCK pin to externally control the direction of power flow
- Footprint for an optional heatsink
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
Models for the following parts are available in LTspice:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
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Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.