The Power by Linear bidirectional buck-boost controller targets redundant battery systems in electric, hybrid, and autonomous vehicles

By
Gina Roos, editor-in-chief

Analog
Devices Inc.
has launched the Power by Linear LT8708/-1 bidirectional buck-boost switching regulator controller
that operates between two batteries that have the same voltage, making it
well-suited for redundancy in autonomous vehicles. The 98% efficient LT8708/-1,
which operates from an input voltage that can be above, below, or equal to the
output voltage, can also be used in electric and hybrid vehicles, where
redundant 12-V, 24-V, or 48-V batteries are commonly found. The LT8708/-1 can
also be used in 48-V/12-V and 48-V/24-V dual-battery systems.

Operating between the two batteries, the LT8708/-1 prevents
system shutdown if one of the batteries fails. The LT8708-1 is used in parallel
with the LT8708 to add power and phases. “The LT8708-1 always operates as a
slave to the master LT8708, can be clocked out of phase, and has the capability
to deliver as much power as the master,” said ADI. In addition, one or more
LT8708-1s can be connected to a single master, which will proportionally
increase power and current capability of the system.

The LT8708/-1 operates with a single inductor over a 2.8-V to
80-V input voltage range and can produce an output voltage from 1.3 V to 80 V.
This can deliver up to several kilowatts of power depending on the choice of
external components and number of phases, said ADI. It also simplifies
bidirectional power conversion in battery/capacitor backup systems that need
regulation of VOUT, VIN, and/or IOUT/IIN
in the forward or reverse direction.

ADI said that the device’s six independent forms of regulation
allow it to be used in numerous applications, including automotive, solar,
telecom, and battery-powered systems.

Key features:

  • Operates with two batteries with the same or different voltages
  • Synchronous rectification: up to 98% efficiency
  • Delivers up to several kilowatts with multiphase operation
  • Single inductor allows VIN above, below, or equal to
    VOUT
  • Six independent forms of regulation:
    o   VIN
    current (forward and reverse)
    o   VOUT
    current (forward and reverse)
    o   VIN
    and VOUT voltage
  • Forward and reverse discontinuous conduction mode supported
  • Supports MODE and DIR pin changes while switching
  • VIN range: 2.8 V (Need EXTVCC > 6.4 V) to
    80 V
  • VOUT range: 1.3 V to 80 V
  • Available in 40-lead 5 × 8-mm QFN with high-voltage pin spacing

The LT8708 is available in three temperature grades, with
operation from –40°C to 125°C for the extended and industrial grades and a
high-temp automotive range of –40°C to 150°C.

Available now, pricing for the LT8708/-1
(5 × 8-mm QFN-40) starts at $6.60.