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Company Logo TE Connectivity

  • PWM Controlled DC to DC Cell Phone Charger

  • Created: May 06, 2015

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Cellular phones are widely used nowadays for its convenience in communicating other people. However, it has limited battery life that is why it basically needs a battery charger to frequently energize the battery. Although battery chargers are available globally, anyone can also build their own for fun. This circuit is a simple micro USB charger that can be useful for most mobile phones. It specifically uses the TE connectivity's micro USB connector that provides a stable connection even after thousands of insertions.

The 4VDC supply cannot charge the cell phone battery unless the current is optimally dimensioned. The use of voltage regulator for making a DC-to-DC charger is not recommended since it requires a heatsink to keep it cool and operative. This makes the unit a bit bulkier and some significant amount of power is wasted in the form of heat, which make it inefficient. The involvement of PWM pulses helps to keep the output suitable to the cell phone circuitry and also the concept involves no heating of the output device, making the entire circuit truly efficient. The voltage input of the circuit is supplied through some standard DC source, ideally from an automobile battery. In addition, the power transistor is used for switching the DC voltage at its collector directly to the cell phone. However, only the average DC voltage is finally fed to the cell phone due to the presence of the 10uF capacitor, which effectively filters the pulsating current and provides a stable, standard 4V to the cell phone.

The TE's micro USB connectors are known for its reliable, robust and versatile system in meeting all USB applications. These are commonly observed in mobile devices that may be integrated for use in various applications such as charging mobile phones, MP3 player, GPS units, tablets, digital cameras/camcorders and other electronic devices.