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

The MAX16984 combines a 5V automotive-grade step-down converter capable of driving up to 2.5A of current, a USB host charger adapter emulator, and a USB protection switch for automotive USB host applications. The USB provides high-ESD protection switches, short-circuit protection, and integrated host charging port detection circuits that adhere to the USB 2.0 battery charging specification, BC1.2 battery charging specification, and Chinese communications industry standard YD/T 1591-2009. They also include circuits for dedicated charging modes for iPod®/iPhone® 1.0A and iPad® 2.1A. HVD+, and HVD-ESD protection features include protection to ±15kV air/±8kV contact discharge for 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 voltages 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 from 220kHz to 2.2MHz options to optimize efficiency, noise, and board space based on application requirements. The converter features an internal high-side n-channel switch and uses a low forward-voltage-drop freewheeling Schottky diode for rectification. There is a small low-side n-channel switch to maintain a fixed frequency at light loads. For low quiescent-current operation requirements, the low-side n-channel switch can be disabled, allowing skip-mode operation at 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 circuitry designed to provide automatic USB voltage adjustment to compensate for captive cable voltage drops associated with automotive applications. The MAX16984 limits USB load current using a fixed internal peak-current threshold of the DC-DC converter and a user-configurable external threshold of the USB load-current sense amplifier.

Key Features

High efficiency DC-DC controller

Operating voltage 4.5V to 28V (42V load dump)

5V, 2.5A output current capability

User-Adjustable USB Current Limit

Fixed frequency operation from 220kHz to 2.2MHz

Forced PWM no-load option

Spread spectrum to reduce EMI

SYNC input frequency stop

Low Q current period skip mode and low Q shutdown

Soft start to reduce inrush current

Integrated output cable voltage drop adjustment

User-adjustable voltage gain

Up to 3m cable length / 600mΩ

USB D+/D- Protection and Host Charger Emulator

4ΩUSB 2.0480Mbps/12Mbps data switch

Integrated iPod/iPhone/iPad charging detection terminal resistor

Supports USB BC1.2 Charging Downstream Port (CDP) and Dedicated Charging Port (DCP) modes

China Communications Industry Standard YD/T 1591-2009

High-speed pass-through mode

Short-to-battery and short-to-VBUS protection

Compatible with USB On-the-Go specifications

Split power supply SUP SUPSW to reduce power consumption

Active-low open-drain fault indication output

Automotive grade ESD protection (HVD±)

±25kV air/±8kV contact discharge ISO 10605

±15kV air/±8kV contact discharge IEC 61000-4-2

±15kV air/±8kV contact discharge (33Ω, 330PF)

Overheat and short circuit protection

Available in 5mm x 5mm, 28-pin TQFN and side-wettable QFND packages

-40°C to +125°C operating temperature range