SMPS (Switch Mode Power Supply) – Full Explanation in Simple Terms

SMPS (Switch Mode Power Supply) – Full Explanation in Simple Terms

In today’s electronics world, SMPS is everywhere – from elevators to laptops, LED TVs to mobile chargers.

But what exactly is SMPS?
Let’s understand it step-by-step, with all the internal parts explained clearly
—
What is SMPS?

SMPS stands for Switch Mode Power Supply.
It converts AC power to regulated DC power using high-speed switching.
Compared to old linear power supplies, SMPS is:
✅ More efficient
✅ Compact
✅ Generates less heat
—
⚙️ SMPS Working – Step by Step:

1️⃣ AC Input

➡️ 230V AC from mains is given as input.

2️⃣ EMI Filter

➡️ Removes unwanted noise & interference from AC line.
➡️ Protects sensitive electronics.

3️⃣ Bridge Rectifier

➡️ Converts AC to unregulated DC using 4 diodes.

4️⃣ Filter Capacitor

➡️ Smooths the DC and removes ripples.

5️⃣ Switching Transistor (MOSFET)

➡️ Converts DC into high-frequency pulses.
➡️ Works like a super-fast ON/OFF switch.

6️⃣ PWM Controller IC

➡️ Controls the switching speed and duty cycle of MOSFET.
➡️ Maintains a stable DC output voltage.

7️⃣ High-Frequency Transformer

➡️ Transfers energy from primary to secondary side.
➡️ Provides voltage step-up/down and isolation.

8️⃣ Secondary Rectifier (Schottky Diodes)

➡️ Converts high-frequency AC from transformer back to DC.

9️⃣ Output Filter (LC Filter)

➡️ Cleans the output DC further using Inductors + Capacitors.
➡️ Final output is smooth and ripple-free.

Feedback Circuit + Opto-Isolator

➡️ Monitors output voltage.
➡️ Sends signal to PWM IC to adjust switching accordingly.
➡️ Provides electrical isolation between input and output.

1️⃣1️⃣ Protection Circuit

➡️ Protects from over-voltage, over-current, short-circuit, and heat.
➡️ Ensures safety – especially important in elevator systems.
—
Why SMPS is Preferred?

✔️ Compact size
✔️ High efficiency (80%–90%)
✔️ Handles voltage fluctuations
✔️ Long life, low maintenance
✔️ Essential in modern control systems

Disclaimer – This post has only been shared for an educational and knowledge-sharing purpose related to Technologies. Information was obtained from the source above source. All rights and credits are reserved for the respective owner(s).

Keep learning and keep growing

Source: LinkedIn

Credits: Mr. Syed Abthahir