Synchronous Buck, High-Brightness LED Controller

The MAX20078 is a high-voltage, synchronous n-channel MOSFET controller for high-current buck LED drivers. The device uses a proprietary 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 wide 4.5V to 65V input range. The device is designed for high-frequency operation and can operate at switching frequencies as high as 1MHz. The 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 nonoverlap time to prevent shoot-through currents during transition. The device includes both analog and PWM dimming. The device includes a 5V VCC regulator capable of delivering 10mA to external circuitry. The device also includes a current monitor that provides an analog 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 space-saving (3mm × 3mm), 16-pin TQFN or a 16-pin TSSOP package and is specified to operate over the -40°C to +125°C automotive temperature range.

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Applications

* Automotive Front Lights

* Automotive Matrix Lights

* Constant-Current Regulators

* Head-Up Displays

* Automotive Ready: AEC-Q100 Qualified

* Wide Input Voltage Range: 4.5V to 65V

* Easy to Design

* No Compensation Components

* Programmable Switching Frequency

* Wide Dimming Ratio Allows High Contrast Ratio

* Analog Dimming

* PWM Dimming

* Suitable for Matrix Lighting

* Maintains Current Regulation While Shorting/Opening Individual LEDs in the String

* Ultra-Fast Response Control Loop Prevents Overshoots and Undershoots

* Fault Detection and Protection

* Overvoltage Protection

* Open and Short Detection

* Thermal Shutdown

* Inductor Current Monitor

* Low-Power Shutdown Mode