Automotive LED lighting controller is quiet and quick

Automotive LED lighting controller is quiet and quick

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By Graham Prophet

MAX20078 synchronous buck, high-brightness LED controller, positioned as the only product available which provides both fast response time and low electromagnetic interference (EMI) for exterior LED lighting and improved safety applications, and which is suitable for matrix lighting designs.


In advanced lighting applications such as matrix lighting, Maxim comments, LED drivers and controllers have challenges when switching LEDs at high speeds which can cause overshoots and undershoots in current. These applications are not easy to design, as they require numerous LEDs located in a densely-concentrated area and EMI can be especially difficult to eliminate. Car makers attempt to achieve low EMI as they experiment with different layouts and filtering methods.


The MAX20078 provides ultra-fast response times enabling smoother transient responses. While eliminating the need for external compensation components, it also offers a wide dimming ratio and features both integrated fault protection and monitoring circuitry. The device allows for fast LED switching and low EMI so that designers no longer need to sacrifice one for the other. No compensation components are required and the part can be programmed for switching frequencies from 100 kHz up to 1 MHz.

The IC is a high-voltage, synchronous n-channel MOSFET controller for high-current buck LED drivers. It uses an average current-mode-control scheme to regulate the inductor current. This control method does not need any control-loop compensation while maintaining nearly constant switching frequency. Inductor current sense is achieved by sensing the current in the bottom synchronous n-channel MOSFET. It does not require any current sense at high voltages. The device operates over a 4.5V to 65V input range. High- and low-side gate drivers have peak source and sink current capability of 2A. The driver block also includes a logic circuit that provides an adaptive non-overlap time to prevent shoot-through currents during transition. The device includes both analogue and PWM dimming, and includes a 5V VCC regulator capable of delivering 10 mA to external circuitry. The device also includes a current monitor that provides an analogue voltage proportional to the inductor current. The device has a fault flag that indicates open and shorts across the output. Protection features include inductor current-limit protection, overvoltage protection, and thermal shutdown. The MAX20078 is available in a 3 × 3mm), 16-pin TQFN or a 16-pin TSSOP package.


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