Switching Regulator - Part 4

Boost Converter:

Simple circuit diagram:

A boost converter (step-up converter) is a DC-to-DC power converter with an output voltage greater than its input voltage.

Operation:

Basic Elements DC source, Switch, inductor,capacitor,Diode and PWM controller. PWM controller controls switch ON/OFF timings.

MOSFET ON Condition:

1. MOSFET is Short
2. Diode is Reverse biased. Blocks the current flow
3. Current flow path DC Source (+) --> Inductor -->MOSFET --> Source (-)
4. Inductor stores the energy on this cycle. (Magnetic field action)

MOSFET OFF Condition:

During OFF condition, 

1. MOSFET is Open
2. Diode is forward biased
3. Current flow path DC Source (+)--> Inductor --> Diode --> Capacitor and Load --Source(-)
4. Inductor dissipates the energy on this cycle. (Magnetic field action)
5. Capacitors stores the energy. (Charging)

Next ON Cycle:

1. MOSFET is Short
2. Diode is Reverse biased. Blocks the current flow
3. Current flow path DC Source (+) --> Inductor -->MOSFET --> Source (-)
4. Another current path: Stored capacitor --> Load -- Source (-)
5. Inductor stores the energy on this cycle. (Magnetic field action)
6. Capacitor dissipates the energy to a load

DC output is depends on the 

1. DC input voltage
2. Duty cycle (0 to 100 %)
3. Switching frequency
4. Inductor and capacitor selection

Typical power boost converter -Low power application:

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