Automotive High-Current Step-Down Converter with USB Protection/Host Charger Adapter Emulation

The MAX20037/MAX20038 ICs combine a 3.5A automotive- grade step-down converter, USB host charger adapter emulator, and USB protection switches for automotive USB host applications. The device family also includes a USB load current-sense amplifier and configurable feedback-adjustment circuit, designed to provide automatic USB voltage compensation for voltage drops in captive cables often found in automotive applications. The ICs limit 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.

The ICs allow flexible configuration options for both stand-alone and supervised applications, and can be programmed for desired operation using both external programming resistors and/or internal I2C registers through the I2C bus.

The ICs are optimized for high-frequency operation and include programmable frequency selection from 310kHz to 2.2MHz, allowing optimization of efficiency, noise, and board space based on application requirements. The fully synchronous DC-DC converters feature integrated high-side and low-side MOSFETs, an external SYNC input/output, and can be configured for spread-spectrum operation.

The MAX20037/MAX20038 are available in a small (5mm x 5mm) 28-pin TQFN package (side-wettable available) designed to minimize required components and layout area.

Design Solution: Add Even More USB Ports to Your Car—In Less Space ›

Applications

* Automotive Connectivity/Telematics * Automotive Radio and Navigation * Dedicated USB Charging Port (DCP) * USB Port for Host and Hub Applications

* One-Chip Solution Directly from Car Battery to Portable Device

* 4.5V to 28V (40V Load Dump) Input Voltage

* 5V, 3.5A Output Current Capability

* Device-Attach Detection Output

* Low-Q Current Skip and Shutdown Modes

* Low-Noise Features Prevent Interference with AM Band and Portable Devices

* Fixed-Frequency 275kHz to 2.2MHz Operation

* Fixed-PWM Option at No Load

* Spread Spectrum for EMI Reduction

* SYNC Input/Output for Frequency Parking

* Optimal USB Power and Communication for Portable Devices

* User-Programmable Voltage Gain Adjusts Output for Up to 600mΩ Cable Resistance

* User-Programmable USB Current Limit

* USB 480Mbps/12Mbps/1.5Mbps Data Switches

* Integrated iPod®/iPhone®/iPad® and Samsung® Charge-Detection Termination Resistors

* Supports USB BC1.2 CDP and DCP Modes

* Supports China YD/T 1591-2009

* Compatible with USB On-the-Go Specification

* Robust Design Keeps Vehicle System and Portable Devices Safe in Automotive Environment

* Short-to-Battery Protection on DC-DC Converter Pins

* Short-to-VBUS Protection on USB Pins (MAX20037)

* Short-to-Battery Protection on USB Pins (MAX20038)

* ± 15kV Air/±8kV Contact ISO 10605*

* ± 15kV Air/±8kV Contact IEC 61000-4-2*

* Reduced Inrush Current with Soft-Start

* Overtemperature Protection

* -40°C to +125°C Operating Temperature Range