This document discusses switched mode power supplies (SMPS). It begins with a general description of power supplies and an overview of different types. It then defines SMPS and describes their advantages over linear power supplies, including lower weight, smaller size, higher efficiency and lower costs. The document outlines the typical block diagram of an SMPS, including input rectification, inversion, output transformation and regulation stages. It also discusses considerations for selecting SMPS topologies and provides examples of their applications.

1. Switched Mode Power Supply

2. Contents:-
• General description of Power Supply
• Advantages/Disadvantages of SMPS
• Block diagram of SMPS
• Uses of SMPS
• Applications of SMPS
• Conclusion

3. Power Supply:-
Any device that supplies electric
power to an electric load.
The different types of power
supplies include:
-Battery
-DC power supply
-AC power supply
-Linear regulated power supply
-Switched mode power supply
-Programmable power supply
-Uninterruptible power supply

4. Switched Mode Power Supply:
 An electrical power supply that incorporates a switching
regulator to convert electrical power efficiently.
 It transfers power from a source, to a load, while
converting voltage and current characteristics.
 Voltage regulation is achieved by varying the ratio of on-
to-off time.

5. Advantages of SMPS over Linear Power Supplies:
• 1. Lower weight
• 2. Smaller size
• 3. Higher efficiency
• 4. Lower power dissipation
• 5. Wide ac input voltage range
• 6. Reduced costs
Disadvantages of SMPS:
1. Complexity of the circuit

6. Block diagram of a SMPS
1. Input rectifier stage:
It is used to convert an ac input to dc. A SMPS with dc
input does not require this stage. The rectifier
produces unregulated dc which is then passed through
the filter circuit.

7. • 2. Inverter stage:
– The inverter stage converts DC, whether directly from the input
or from the rectifier stage described above, to AC by running it
through a power oscillator, whose output transformer is very
small with few windings at a frequency of tens or hundreds
of kilohertz.
3. Output transformer:
- If the output required is to be isolated from input, the inverted
AC is used to draw the primary windings of a high frequency
transformer. This converts the voltage up or down to the
required output level on it’s secondary winding.
4. Output rectifier:
- If the dc output is required, the ac output from the transformer
is rectified.
5. Regulation:
- Feedback circuit monitors the output voltage and compares it
with the reference voltage.

8. Factors to be considered while selecting a
topology for a particular application:-
• 1. Is input-to-output dielectric isolation required for the application?
• 2. Are multiple outputs required?
• 3. Does the prospective topology place a reasonable voltage stress
across the voltage semiconductors?
• 4. Does the prospective topology place a reasonable current stress
across the voltage semiconductors?
• 5. How much of the input voltage is placed across the primary
transformer winding or inductor?
• Typical maximum output power available from each topology:
Converter Topology Maximum output power
Flyback 200W
Forward 300W
Push-pull 500W
Half bridge 1000W
Full bridge >1000W

9. Use of non-isolated topologies:
• Non isolated topologies are the simplest, with the three basic types using a
single inductor for energy storage.
Type Power(W) Relative
Cost
Energy
Storage
Voltage Relation Features
Buck 0-1000 1.0 Single
inductor
0 ≤ Out ≤ In
V2=D.V1
Continuous
current at
output
Boost 0-150 1.0 Single
inductor
Out ≥ In
V2=V1.[(1)/(1-D)]
Continuous
current at
input
Buck-
boost
0-150 1.0 Single
inductor
Out ≤ 0
V2= -V1[(D)/(1-D)]
No
continuous
current

10. Applications of SMPS:-
• 1. Machine tool industries
• 2. Security Systems
• (Closed circuit cameras)
• 3. Support supplies with PLC’s
• 4. Personal Computers
• 5. Mobile Phone chargers

11. SMPS in Indian markets:
iball 600W
Rs. 4700
Antec 750W
Rs. 6600
Cooler master 550W
Rs. 3800
Corsair 750W
Rs. 10700
Seasonic 500W
Rs. 3600
UMAX 450W
Rs. 570

12. Conclusion:
• The most common SMPS
topologies: flyback, push-pull, half
bridge and full bridge converters
have been outlined.
• Each has it’s own particular
operating characteristics and
advantages, which makes it
suitable to particular applications.
• Some of the most common
applications of SMPS have been
discussed.

13. Thank you!!