USB power supply is designed for automotive environments

October 05, 2015 // By Christoph Hammerschmidt
The E.522.43 from chipmaker Elmos AG is a USB 2.0 compatible power supply with comprehensive protection functions for deployment in vehicles. It detects automatically dedicated BC1.2 charging ports as well as the removal of the connected USB device, which makes the chip ideally suited for stand-alone applications without external microprocessor.

The IC offers extensible pin configurability and supports all USB charging downstream loads according to the Battery Charging Specification rev. 1.2; in addition it can emulate all currently known specific USB charging devices. The bus voltage can be increased as a function of the current (negative resistance), enabling an optimal charging process even at high current with cable-bound losses.


The system setup can be performed through three configuration pins with a resistance dividers for the internal power supply. It is possible to set up any combination of USB port, switching frequency, overcurrent handling and their limit values. Multiple mechanisms to detect erroneous resistance coding prevent activating the IC in the case of failures.


The internal switching power regulator guarantees an efficient USB supply voltage of 5 V ±3% at a maximum output current of 2.5A from an input voltage between 6 and 32V. The switching frequency can be adjusted to the 250 kHz, 500 kHz and 2 MHz which can be synchronised within ±25% when connected with another device in master-slave configuration.


The design of the E.522.43 took into account the specific robustness requirements of automotive environments. For instance, it meets ISO7637 for input surges, short circuit protection for the USB interface (bus and data lines), over- and undervoltage monitoring of the USB supply voltage, monitoring of the internal reference voltages and signalisation of failure states and errors through an interrupt output. The component is certified according to AEC-Q100. It comes in a 20-pin QFN package with high thermal efficiency to withstand operating temperatures up to 105°C.


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