Analog Devices announces the Power by Linear™ LT8708/-1,
a 98% efficient bidirectional buck-boost switching regulator controller
that operates between two batteries that have the same voltage, which
are ideal for redundancy in self-driving cars. The
LT8708/-1 can use an input voltage that is above, below or equal to the
output voltage, making it well suited for two each 12V, 24V or 48V
batteries commonly found in electric and hybrid vehicles. It operates
between two batteries and prevents system shutdown should one of the
batteries fail. The LT8708/-1 can also be used in 48V/12V and 48V/24V
dual battery systems.
The LT8708/-1 operates with a single inductor over
a 2.8V to 80V input voltage range and can produce an output voltage
from 1.3V to 80V, delivering up to several kilowatts of power depending
on the choice of external components and number of phases. It simplifies
bidirectional power conversion in battery/capacitor backup systems that
need regulation of VOUT, VIN, and/or IOUT, IIN,
both in the forward or reverse direction. This device’s six independent
forms of regulation allow it to be used in numerous applications.
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. One or more slaves can be connected
to a single master, proportionally increasing power and current
capability of the system.
Another application is for an input voltage to
power a load, where this same input voltage is used to power a LT8708/-1
circuit that charges a battery or bank of supercapacitors. When the
input voltage goes away, the load maintains power without disruption
from the battery or supercaps by way of the LT8708’s bidirectional
capability.
Forward and reverse current can be monitored and
limited for the input and output sides of the converter. All four
current limits (forward input, reverse input, forward output and reverse
output) can be set independently using four resistors. In combination
with the DIR (direction) pin, the chip can be configured to process
power from VIN to VOUT or from VOUT to VIN ideal for automotive, solar, telecom and battery-powered systems
The LT8708 is available in a 5mm × 8mm QFN-40
package. Three temperature grades are available, with operation from –40
to 125°C for the extended and industrial grades and a high temp
automotive range of –40°C to 150°C.
