What’s inside a phone charger ?

Have you ever wondered what inside a charger that gives our phone the power to sustain a day or longer.

Keep reading fellas as we will be exploring the phone charger today.

Here is the block diagram of the most basic type of a charger circuit.


The input to the charger is 220V AC VOLTAGE . But the phone batteries are rated at 5V .So there is a need to bring down the 220V to a lower voltage. This is done using a step down transformer.

STEP DOWN TRANSFORMER : Step down transformers converts the 220V AC to a lower AC voltage.The lower voltage depends on the transformer being used. The transformer is selected based on the voltage and current ratings of the load

RECTIFIER : The output of the transformer is AC. But the cell phone batteries need DC supply. So the AC needs to be converted into DC and that is done by a circuit called rectifier. Rectifier is basically diodes connected together such that it converts the AC into pulsating DC signal. The output of the Rectifier is not pure DC. It is pulsating i.e it contains ripples that needs to be removed.

FILTER : Filter circuit is used to remove the ripples from the DC signal. It usually involves capacitors. Capacitors bypasses the DC signal and blocks the AC signal .So we get a DC signal without ripples at the output.

REGULATOR : As the name suggests it is used to regulate the output voltage. The input to battery shouldn’t be fluctuating . It should be a steady DC supply which is ensured by the regulator. The output of the regulator is then fed to the phone using a USB or any other type of connector.

So this is whats inside a charger. Well this isn’t enough to charge a phone battery .There are different circuits to ensure proper and safe charging of the batteries. All those will be discussed in detail in the next blog .

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