55V buck controller targets automotive applications

4th August 2014
Nat Bowers

Claimed to be the most versatile high voltage buck solution available, Intersil has introduced a 55V synchronous buck controller with 3A integrated high side and low side drivers. The ISL78268 provides up to 96% step-down efficiency for a wide variety of load currents from under 5 to over 25A to support 12, 24, or 48V high current buck requirements for automotive and industrial applications.

Designers often have to balance power conversion efficiency against size and noise constraints for heavy load applications. This often requires the power stage to be tailored to the load in question, as well as trade-offs among component selection, switching frequency and output ripple. Designed specifically to be flexible, the ISL78268 can be used regardless of the optimisation balance. Average current limiting extends battery life in battery charging applications and avoids inductor current runaway in supercap charging applications.

The synchronous buck controller, integrates a peak current mode synchronous PWM controller, a dedicated constant current control loop and high-side and low-side FET drivers featuring adaptive dead time control. The ISL78268 facilitates easy conversion from high primary (typically 12, 24 or 48V) rails to lower secondary (typically 3.3, 5.0 or 12V) rails. The AEC-Q100 qualified device features a low shutdown current of 3uA.

With 55V inputs, the controller is suited for automotive applications. Minimising dead time to reduce switching losses, improve efficiency and reduce excess heat dissipation, the integrated 3A driver allows it to sharply switch small power FETs or parallel combinations of large FETs. Therefore designs are simplified and time-to-market reduced since a single buck controller can be used across a variety of load requirements.

Philip Chesley, Vice President, Precision Products, Intersil, comments: “The ISL78268 was designed to enable power conversion with very high efficiency and improved performance over traditional solutions. The unique combination of features provides customers with a very versatile solution that can be used and re-used across their high voltage designs.”

Available now in a 24 lead 4x4mm QFN package, the ISL78268 is priced from $2.45 (USD) in 1,000 unit quantities. Intersil also provides the ISL78268EVAL1Z evaluation kit for $83.33 (USD).

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