Multiphase bidirectional current controller for dual automotive batteries

March 21, 2017 // By Graham Prophet
Texas Instruments claims a first with its fully integrated multiphase bidirectional DC/DC current controller, designed to efficiently transfer power of over 500W per phase between dual 48-V and 12-V automotive battery systems.

The highly integrated LM5170-Q1 analogue controller features an average current-mode control method that overcomes the challenges of high-component-count, full digital control schemes.


48-V battery and standard 12-V automotive batteries in HEVs are typically managed using a digital control scheme, which includes multiple discrete components such as current-sense amplifiers, gate drivers and protection circuits. These full digital control schemes are bulky and expensive. To solve this challenge while improving performance and system reliability, TI offers a mixed architecture in which the microcontroller handles higher-level intelligent management, and the highly integrated LM5170-Q1 analogue controller provides the power conversion.


The LM5170-Q1’s average current-mode control method improves performance, simplifies implementation and reduces cost, described in “ Selecting a bidirectional converter control schem e”. The controller’s 1%-accurate bidirectional current regulation ensures precise power transfer, with greater than 97 percent efficiency and current monitoring of up to 99% accuracy. Integrated 5-A peak half-bridge gate drivers offer high power capability, and diode emulation mode of the synchronous rectifier MOSFETs prevents negative current and enhances light load efficiency. The LM5170-Q1 is AEC-Q100 qualified.


The LM5170-Q1 in a 48-pin, 9 x 9-mm quad flat package (QFP) is priced at $5.84 (1,000). Support includes the LM5170EVM-BIDIR evaluation module , PSpice transient model and LM5170-Q1 quick-start DC/DC synchronous buck converter design tool .


TI has a blog post , “Interconnecting automotive 48V and 12V rails in dual battery systems” on the challenges of designing a power supply for hybrid electric vehicles.