Synchronous Buck, High-Brightness LED Controller

Description

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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 V_CC 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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Key Features

• 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

Applications/Uses

• Automotive Front Lights
• Automotive Matrix Lights
• Constant-Current Regulators
• Head-Up Displays