Susie Maestre

user Electronics Engineer

city Innovuze Solutions Inc.

  • Automotive USB Charging Port Controller and Power Switch

  • Created: Jan 12, 2017

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The use of universal USB charging port in the automotive industry has provided a solution to bulky and inefficient dedicated chargers. It offers flexibility to use any device with a USB charging cable. This design is a great use to eliminate the use of cigarette lighter receptacle in cars, and use a USB port charger to charge 5-V portable devices. This design features TPS2549 power management IC from Texas Instruments. This particular IC is a USB charging port controller and power switch with a current-sense output that is able to control an upstream power supply. It maintains 5V at the USB port even with heavy charging currents.

This reference design enables full evaluation of the TPS2549 device. Since the required voltage of the USB is 5V, the voltage from the automotive, which is typically 12V, must be regulated. The 12V is applied through the connector J3. The input stage consists of an input switch (Q1), protection (D2), and an input filter (L1, C1, C2, C3, C5). The voltage at the 5VDC node is regulated by the LM53603AQ buck regulator (U1) and associated circuitry. This provides a nominal 5V, 3A output for the TPS2549 (U2). The TPS2549 internal power switch connects the 5VDC node to VBUS at the downstream facing USB connector, J1. When the internal power switch is ON, the LED5 (green) will illuminate. Additionally, the TPS2549 device integrates short-to VBUS protection for D+ and D– to prevent damage when D+ and/or D– unexpectedly short to VBUS. The LED4 and LED3 are used to detect the status and fault conditions of TPS2549.

This design provides the electrical signatures on DP_IN and DM_IN to support all current charging schemes. It incorporates USB cable voltage drop compensation by linearly sensing the port current and automatically adjusting the output voltage of the LM53603AQ to keep the cable end device voltage within the normal operating range. It is made specifically for automotive chargers, but it also useful in wall charging chargers and USB ports (host and hubs).



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