Power bank is a device that stores power in a Li-Ion battery. It is being increasingly used as reserve charger for hand held/portable devices like mobile phones, tablets etc. A typical power bank has these components:
Charging circuit: it implements the complete charging logic for a Lithium Ion battery
Battery Protection circuit: it takes care of over charge and over temperature protections during charging and over discharge, over load and temperature protections during discharge.
Boost Converter: it steps up the 3V - 4.2V battery voltage to 5V.
Controller functions:
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Monitors output voltage and controls the pulse-width of gate drive of the MOSFET in boost converter.
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Measures battery voltage and disables boost converter when battery voltage reaches the low voltage threshold.
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Monitors the load current, turns off the boost converter when load is disconnected or when there is an overload.
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Drives status LEDs to display battery level and charging or load status.
PSoC 1 provides a single-chip solution that integrates battery charging, battery protection and controller functions in a single chip; thus reducing BOM and PCB size. If required, an external hardware battery protection circuit can also be added for additional battery protection.