What is SMPS and Its Function

What is SMPS (Switched Mode Power Supply)

Switched Mode Power Supply (SMPS) is an electronic device that is used to convert DC to DC, AC to DC loads, a switched-mode power supply allay no power and The main advantage of the SMPS is greater efficiency than linear regulators because the switching transistor allays little power when acting as a switch.

In early days linear power supplies were commonly used in personal computers, which used large transformers and linear regulators, which dissipate most of the excess energy as waste heat, that’s why they introduce SMPS which uses an inductor to store energy in a magnetic field


Power IN

The power-IN connector as shown in the figure it is an input for mains supply. A power cable is inserted in power in the socket, the input supply gets converted to DC supply.

Power OUT

The power-OUT connector which is shown in the above figure is connected directly to the Power-IN connector from inside the supply unit. It supplies the same AC supply that is fed to a power-IN socket. The power-OUT connector is used to give supply to any display unit like a monitor.

Types of SMPS

  1. DC-DC Converter 

This is the type of an SMPS converter in which you get the CURRENT near the SMPS, which is AC before converting it to DC, which passes through the current DC Converter first passes through the primary side of the Step-Down Transformer. , This is a part of a step-down transformer SMPS which is 50 Hz, this voltage rectified and filter holes passes in the second part of the transformer, now it goes out of the output voltage power and moves into different parts. The output of this is sent back to the switch once more to control the voltage.

  1. Forward Converter 

This is also a converter that can carry current through choke whether or not the transistor does its job or not. When the transistor is completely closed, then this work diode. So this is why the energy inside the load is done at the time of both the off and on, but choke keeps the energy, at ON Period and some energy he sends to the Output Load.

  1. Flyback Converter

In the Flyback Converter, when the switch on remains, the inductor’s Magnetic Field Energy Store does. When the switch on is in position, the energy output is empty in the voltage circuit. Duty Cycle determines the output voltage.

  1. Self-Oscillating Flyback Converter

This is the most posture and basic converter that works on the flyback. At the time of the transduction, the switching transistor increases from transfer to primarily linearly according to a slope.

Advantage of SMPS

  1. Highly efficient with lower levels of energy being dissipated as heat.
  2. Useful in voltage step up and step down applications as they provide with high-efficiency voltage conversions.

ATX Connector in SMPS

ATX Connector is a 24-pin female connector which is used to supply DC supply to the motherboards. Various color-coded wires connect to this connector and each colored wire supplies distinct DC voltage. it has a different code of wire which is explained below.

ATX Connector

Pin No. Name /Voltage Color Code Description
1 3.3V Orange +3.3V DC
2 3.3V Orange +3.3V DC
3 COM Black Ground
4 5V Red +5V DC
5 COM Black Ground
6 5V Red +5V DC
7 COM Black Ground
8 PWR-OK Gray +5V DC when power is OK
9 5VSB Purple +5V DC Standby Voltage
10 12V Yellow +12V DC
11 12V Yellow +12V DC
12 3.3V Orange +3.3V DC
13 3.3V Orange +3.3V DC
14 -12V Blue -12V DC
15 COM Black Ground
16 PS_ON Green Power Supply ON
17 COM Black Ground
18 COM Black Ground
19 COM Black Ground
20 -5V White It is used with older type AT class
21 +5V Red +5V DC
22 +5V Red +5V DC
23 +5V Red +5V DC
24 COM Black Ground

To know smps is working or not without motherboard you need to one copper wire and bend it in a  ‘U’ shape and insert one wire into the Green terminal (on third 3rd)  and another wire in Black terminal of 24 atx connector pin.

ATX 12V Connector (4 Pin Motherboard Power Connector)

This 4 pin connector is used to provide electrical current to the CPU and must be installed on the motherboard.

Pin No. Name /Voltage Color Code Description
1 COM Black Ground
2 COM Black Ground
3 +12VDC Yellow +12 VDC
4 +12VDC Yellow +12 VDC

4-PIN connectors

It is also known as Hard drive connector cable this cable can be used in various peripheral devices like Harddisk, DVD Drive, CD Drive Etc and this connector give DC power to each peripheral device

4 Pin ATX Connector

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