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MAX16984：Automotive High-Current Step-Down Converter with USB Protection/Host Charger Adapter Emulator

Industry's First USB Data Protection Switch that Integrates a High-Voltage, Feedback-Adjustable DC-DC Converter

The MAX16984 combines a 5V automotive-grade step-down converter capable of driving up to 2.5A, a USB host charger adapter emulator, and USB protection switches for automotive USB host applications. The USB protection switches provide high-ESD, short-circuit protection and feature integrated host-charger port-detection circuitry adhering to the USB 2.0 Battery Charging Specification BC1.2 battery charging specification and Chinese Telecommunication Industry Standard YD/T 1591-2009. They also include circuitry for iPod®/iPhone® 1.0A and iPad® 2.1A dedicated charging modes. The HVD+ and HVD- ESD protection features include protection to ±15kV Air/±8kV Contact on the HVD+ and HVD- outputs to the IEC 61000-4-2 model and 330Ω, 330pF ESD model. The high-efficiency step-down DC-DC converter operates from a voltage up to 28V and is protected from load dump transients up to 42V. The device is optimized for high-frequency operation and includes resistor-programmable frequency selection from 220kHz to 2.2MHz to allow optimization of efficiency, noise, and board space based on application requirements. The converter has an internal high-side n-channel switch and uses a low forward-drop freewheeling Schottky diode for rectification. There is a small low-side n-channel switch to maintain fixed frequency under light loads. For lower quiescent current operation requirements, the low-side n-channel switch can be disabled to allow skip mode operation under light loads. The converter can deliver up to 2.1A of continuous current at 105°C. The MAX16984S has an integrated spread-spectrum oscillator to improve EMI performance. The MAX16984 also includes a USB load current-sense amplifier and configurable feedback adjustment circuit designed to provide automatic USB voltage adjustment to compensate for voltage drops in captive cables associated with automotive applications. The MAX16984 limits the USB load current using both a fixed internal peak current threshold of the DC-DC converter and a user-configurable external USB load current-sense amplifier threshold.

Key Features Integrated DC-DC and USB Host Charge Emulator Enables 1-Chip Solution Directly from Car Battery to Portable Device 4.5V to 28V (42V Load Dump) Operating Voltage 5V, 2.5A Output Current Capability Low-Q Current Skip and Shutdown Modes Soft-Start Reduces Inrush Current Low-Noise Features Prevent Interference with AM Band and Portable Devices Fixed-Frequency 220kHz to 2.2MHz Operation Forced-PWM Option at No Load Spread Spectrum for EMI Reduction SYNC Input for Frequency Parking Optimal USB Power and Communication for Portable Devices User-Adjustable Voltage Gain Adjusts Output Between 5V and 6.15V for Cable Compensation ±3% Accuracy User-Adjustable USB Current Limit 4Ω USB 2.0 480Mbps/12Mbps Data Switches Integrated iPod/iPhone/iPad Charge-Detection Termination Resistors Supports USB BC1.2 Charging Downstream Port(CDP) and Dedicated Charging Port (DCP) Modes Supports Chinese Telecommunication Industry Standard YD/T 1591-2009 Compatible with USB On-the-Go Specification High-Speed Pass-Through Mode Robust Design Keeps Vehicle System and Portable Devices Safe in Automotive Environment Short-to-Battery Protection on DC-DC Converter Short-to-Battery Protection on USB Pins ±25kV Air/±8kV Contact ISO 10605 ±15kV Air/±8kV Contact IEC 61000-4-2 ±15kV Air/±8kV Contact (330Ω, 330pF) Fault-Indication Active-Low, Open-Drain Output Reduced Inrush Current with Soft-Start Overtemperature Protection -40°C to +125°C Operating Temperature Range 28-Pin, 5mm x 5mm, TQFN and Side-Wettable QFND Packages

MAX16984: Typical Operating Circuit Applications/Uses Automotive Connectivity Automotive Radio and Navigation Dedicated USB Power Charger Telematics USB Port for Host and Hub Applications

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