LTC3871 is a 100V/30V bidirectional two phase synchronous buck or boost controller, for 48V/12V automotive dual battery systems; it provides bidirectional DC/DC control and battery charging between the 12V and 48V boardnets, operating in buck mode from the 48V bus to the 12V bus or in boost mode from 12V to 48V. by Graham Prophet @ edn-europe.com
The LTC®3871 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 LTC3871 allows both batteries to supply energy to the load simultaneously by converting energy from one battery to the other.
48V/12V DC/DC for automotive dual-rails offers bidirectional power flows – [Link]