How many portable devices do you have on you right now? How many of these can be charged from a USB port? How many times do you have to charge each of these?
Now, think about how much time you spend in your car every day. You commute to and from the office, then out to lunch and back. Maybe, you go to a soccer or baseball game in the evening with your friends or children. What if your portable devices could be charging for all of the time that you’re in your car? They would always be charged and ready to go when needed.
Automobile manufacturers are continuously adding more and more USB ports to new vehicles. Insufficient are just two ports for the entire back seat. Now, at least two ports are needed per seat—and maybe more will be needed in the future. Of course, with this increase in the number of USB ports comes an increase in the current drawn by each device plugged in. In order to avoid making the car heavier and more expensive, the wire gauge from the engine control unit (ECU) remains the same, while more current is delivered. Clearly, there is a higher voltage drop across this wire and less voltage at the port. I explain why this matters in more detail in a previous blog.
In order to provide sufficient voltage to these USB ports, a simple change is needed to the existing power delivery circuit. By adding the INA213 current sense amplifier, the voltage at the USB port where your portable devices are can be dynamically adjusted, based on the current delivered to the USB ports. In this way, the 5V at your device is well-regulated even with small gauge wires and the long distance from the ECU to the backseat ports.
By adding a small and low cost current sense amplifier to the existing TPS62130A-Q1 power supply, the same USB port power architecture is kept with minimal increases in Bill of Materials (BOM) cost or Printed Circuit Board (PCB) size. The result is overcoming a key technical issue with multiple USB ports in vehicles—overcoming the voltage drop on the wiring to deliver the right voltage to the portable devices to charge them quickly.