Analog Devices announces the Power by Linear LTC7815, a high frequency (up to 2.25MHz) triple output (buck, buck, boost) synchronous DC/DC controller that maintains regulation of all output voltages under automotive cold crank conditions.

12V automotive batteries can droop to below 4V during engine restarts or cold cranking, which can cause infotainment systems and other electrical components that operate at 5V or higher to reset.

This high-efficiency synchronous boost converter prevents output voltage dropout when the car battery voltage droops by powering two step-down converters. This is a very useful feature in automotive start/stop systems that shut off the engine when the car is idle to save fuel. Alternatively, these buck controllers can be powered from the input for a general-purpose triple-output controller.

The LTC7815 operates over an input voltage of 4.5V to 38V during startup, and maintains operation down to 2.5V after startup. The synchronous boost converter can produce an output voltage up to 60V and operates with the synchronous switch in the "ON" state at 100% duty cycle to pass through the input voltage at high inputs to reduce noise and maximize efficiency. The two step-down converters can produce output voltages from 0.8V to 24V with the entire system capable of producing an output voltage of up to 95%. The low minimum on-time of 45 ns enables voltage conversion at a high step-down ratio while switching at 2 MHz, avoiding critical noise-sensitive frequency bands such as AM radio and reducing the size of external components.

The LTC7815 can be configured for Burst Mode operation, which regulates the output voltage at no load, a useful feature for preserving battery run time in always-on systems, while reducing quiescent current to only 28μA per channel (38μA for all three channels). The powerful 1.1Ω onboard all N-channel MOSFET gate drivers minimize switching losses and provide output currents of over 10s of amps per channel, depending on external components. Additionally, the output current of each converter can be sensed by monitoring the voltage drop across the inductor (DCR) or by using a separate sense resistor.

The LTC7815's constant frequency current mode architecture provides a selectable switching frequency between 320kHz and 2.25MHz or can be synchronized to an external clock over the same range.