Integrated boost controllers enable smaller designs

Operating from a 12V battery supply, these devices boost the output voltage to 24, 36 or 48V for premium 200 to 800W trunk audio amplifiers, start-stop systems and headlamp LED strings. Both controllers also address the rigorous demands of industrial and telecom applications where a step-up DC/DC converter must deliver high power in a small solution size.

The ISL78227 and ISL78229 enable a modular design for systems requiring power and thermal scalability. They support wide input and output ranges of 5 to 55V and deliver greater than 95% efficiency to reduce power loss and heat dissipation. The ability to interleave two controllers for a four-phase application effectively doubles the output power and reduces input/output ripple, allowing power supply designers to use smaller capacitors to save board space and lower their bill of materials cost.

Numerous protection features keep the ISL78227 and ISL78229 operating under virtually any condition. Their unique soft-on function ensures smooth transition from discontinuous-conduction mode (DCM) to continuous-conduction mode (CCM) after completing a soft-start, keeping the power supply safe under all start-up conditions.

The ISL78227 and ISL78229 also offer a unique envelope-tracking feature that dynamically adjusts or scales the output voltage on the fly to meet all system load demands. 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. And to simplify the task of attaining the ISO 26262 Automotive Safety Integrity Level (ASIL) rating, the ISL78229 offers a digital PMBus(TM) interface for advanced control, telemetry and diagnostics. Having the PMBus interface on-chip eliminates the need for dedicated telemetry circuitry required to configure fault types, system recovery and monitoring.

"The ISL78227 and ISL78229 enable high power step-up applications in a small solution size that deliver high efficiency and offer multiple layers of power supply protection," said Philip Chesley, Senior Vice President of Precision Products, Intersil. "A unique combination of innovative features, integrated tracking and a PMBus option provides customers with robust and easy to use solutions for their high voltage designs."

Key Features and Specifications of ISL78227 and ISL78229

• Provides input/output voltage from 5 to 55V, and withstands transients up to 60V
• Supports synchronous or standard boost topology, and uses peak current mode control for fast line response with adjustable slope compensation
• Configurable for single phase, 2-phase and 4-phase operation, enabling high efficiency
• Adjustable switching frequency from 50kHz to 1.1MHz, and external synchronization
• Two layers of over-current protection prevents inductor current run-away system damage
• Negative current protection prevents large currents that can damage the high-side FET
• Average current limiting allows high current for brief heavy load periods, and prevents longer periods that can cause overheating
• Soft-on capability provides a smooth transition from soft-start to full operation in CCM
• Adaptive and programmable dead-time control prevents shoot-through current
• Selectable diode emulation and phase dropping optimises light load efficiency
• AEC-Q100 qualified for operation from -40 to +125°C
• Wettable flank QFN package allows optical inspection of solder joints for lower manufacturing cost

PowerNavigator GUI Simplifies Digital Power Designs 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.

The ISL78227 and ISL78229 can be combined with the ISL78206 40V/2.5A synchronous buck controller, ISL78310 1A LDO, and ISL78233 3A synchronous buck regulator to provide a complete power solution for an automotive audio amplifier power supply.