Automotive Electronics

Versatile Buck Controller for High-Current Industrial and Automotive Designs

Intersil Corporation today announced the ISL78268 55V synchronous buck controller with 3A integrated high-side and low-side drivers. Claimed to be the most-versatile high-voltage buck solution available, the ISL78268 buck controller provides high step-down efficiency for a wide variety of load currents from under 5 to over 25A, enabling it to support virtually every 12-, 24-, or 48-V high-current buck requirement for automotive and industrial applications.

For heavy load applications, designers often have to balance power conversion efficiency against size and noise constraints. This requires making trade-offs among component selection, switching frequency, and output ripple and often requires the power stage to be tailored to the load in question. The ISL78268 buck solution was designed specifically to be flexible so that it can be used regardless of the optimization balance.

The ISL78268 buck controller enables easy conversion from high primary rails (typically 12-, 24- or 48-V) to lower secondary rails (such as 3.3-, 5.0- or 12-V). It fully integrates both a peak current-mode synchronous pwm controller and a dedicated constant-current control loop as well as high-side and low-side FET drivers that have adaptive dead-time control. The ISL78268 device's tolerance of 55V inputs makes it suited for automotive applications, including support for the 12V clamped load-dump specifications and new 48V power system being adopted by European OEMs.

The integrated 3A driver allows the ISL78268 buck controller to sharply switch small power FETs or parallel combinations of large FETs while minimizing dead time to reduce switching losses, improve efficiency and reduce excess heat dissipation. This allows a single buck controller to be used across a wide variety of load requirements, simplifying design and reducing time-to-market.

"The ISL78268 was designed to enable power conversion with very high efficiency and improved performance over traditional solutions," said Philip Chesley, vice president of Intersil's Precision Products. "The unique combination of features provides customers with a very versatile solution that can be used and re-used across their high voltage designs."

Features and Specifications: Supports 5-25A loads and can be used in a two-phase, current sharing configuration to support loads up to 50A; 55V input tolerance (60V absolute maximum); Integrated 3A FET drivers and PWM controller for cycle-by-cycle peak current limiting; Provides average current limiting to extend battery life in battery charging applications and avoid inductor current runaway in supercap charging applications; Adaptive dead-time control to prevent overlap current and minimize body diode conduction losses with varying sized power FETs; Selectable diode emulation and burst mode for light loads; Adjustable switching frequency from 50kHz to 1.1MHz; Low shutdown current of 3uA; and it is AEC-Q100 qualified.

The ISL78268 is available now. Pricing for the ISL78268 buck controller starts at $2.45 USD in 1k quantities. The ISL78268 is offered in a 24 lead 4x4mm QFN package. The ISL78268 is supported by the ISL78268EVAL1Z, evaluation kit available for $83.33 USD each.

Intersil Corporation
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