Power Semiconductors

Two-Phase Synchronous Boost Controllers Enable Robust Step-Up DC/DC Converter Design

07 March 2016

For smaller, robust step-up DC/DC converters aimed at automotive, industrial and telecom applications, Intersil Corp. has released two new 55 V two-phase synchronous boost controllers with integrated high-side and low-side MOSFET drivers. Operating from a 12 V battery supply, the new synchronous controllers, ISL78227 and ISL78229, boost output voltage to 24 V, 36 V or 48 V for premium 200 W to 800 W trunk audio amplifiers, start-stop systems, and headlamp LED strings. The controllers, in fact, are designed to deliver high power from a smaller footprint.

Integrated two-phase synchronous boost controllers streamline automotive power system design.Integrated two-phase synchronous boost controllers streamline automotive power system design.The ISL78227 and ISL78229 controllers support wide input and output voltage ranges of 5 V to 55 V and deliver greater than 95% efficiency to reduce power loss and heat dissipation. Plus, for higher power output, two controllers can be interleaved for a four-phase solution that effectively doubles the output power and reduces input/output ripple. It also allows designers to use smaller capacitors to save board space and lower their bill of materials (BOM) cost. Furthermore, the boost controllers also offer numerous protection features for operating under virtually any condition. To keep the power supply safe under all start-up conditions, their soft-on function ensures smooth transition from discontinuous-conduction mode (DCM) to continuous-conduction mode (CCM) after completing a soft-start.

To meet system load demands, ISL78227 and ISL78229 also offer an envelope-tracking feature that dynamically adjusts or scales the output voltage on the fly. For example, whenever the battery supply is low, power consumption of various components such as the audio amplifier must be limited, especially if the radio is on while the engine is off. Transient events such as the start-stop system restarting the engine also require on-the-fly voltage adjustments. Also, to simplify the task of attaining the ISO 26262 automotive safety integrity level (ASIL) rating, the ISL78229 offers a digital PMBus interface for advanced control, telemetry and diagnostics.

Intersil's PowerNavigator software simplifies the ISL78229's PMBus configuration, validation, monitoring, and telemetry. The tool makes it easy to change features and functions of a digital power supply design without writing a single line of code.

While the 55 V synchronous boost controller ISL78227 comes in a 5 mm x 5 mm, 32-lead WFQFN package, ISL78229 with PMBus is available in a 6 mm x 6 mm, 40-lead WFQFN package. In 1k quantities, ISL78227 is priced at $3.45 USD and ISL78229 at $3.95 USD, respectively.

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