SMPS

SMPS

Power is important for the working of any electronic device, such as computers. The Power Supply is essential for the functioning of the computer and its conditional components. Power issues probably are more responsible for more PC Problems than any other single source.
                                  A Switched Mode Power Supply (SMPS), is an electronic power supply unit. It helps to convert the input power to a supply unit. It helps you to convert the input power to a controlled Voltage. A computer works on DC power supply; however, the power socket provides you with AC power supply.
                                              

Fig: SMPS

Power Supply:
The power is supplied to the computer in two stages. In the first stage, the power is transmitted to the computer through a power transmitted to the computer through a power cord from the power socket. In the second stage, the internal power supply transforms this standard household electricity into the form that the computer needs.
Elements of Power Supply:
There are three main elements in a basic power supply namely Transformer, Rectifier and Filter Depending on the requirements of the user.
1. Transformer: It converts the AC Line voltage to a more appropriate voltage level according to the needs of the circuit to be powered. The AC Line voltage is not suitable for electronic circuits. Most of the circuits require considerably lower voltage while a few require higher voltage.

2. Rectifier: It Prevent the occurrence of alteration between the transformer and the AC line. It also forces the current to flow in one direction is known as rectification and the circuit that accomplishes this task is known as the rectifier.

3. Filter: It reduces the pulses from the rectifier to a much smaller ripple voltage. A properly designed filter provides a DC output voltage with only a small AC ripple.
                                                        

Types of Power Supply:
In the reference to electronic devices, power supply can be classified into two major categories:
1. Liner Power Supply
2. SMPS

1. Liner Power Supply: - A Liner Power Supply powered by AC, uses a transformer to convert the voltage from the mains to a different, usually lower voltage. If you are using it to produce a DC, then you need to use a rectifier. To smooth the pulsating current from the rectifier, a capacitor is used. But still there is some small periodic deviation from smooth direct current will remain which is known as a ripple. The unregulated power supply produces the voltage that varies depending on the load and on variation in the AC supply voltage.

2. SMPS: - In SMPS, to obtain DC voltage, the AC mains input is directly rectified without the use of a transformer. Then, a high speed electronic switch is used to slice this voltage into small pieces. As the power output requirements increases, the size of these slices also grows.
                                                        

Power Connectors:
Power Connector is an electrical connector that is used to carry DC or low frequency AC power with the help of power connectors, the power supply unit provides current to the different components of a system which includes motherboard, hard disk drive, floppy disk drive and different other components.
                                                         

Fig: Different Types of Connector

AT Power Connectors:
AT (Advanced Technology) power connector have two 6-wire connectors named P8 and P9 which are to be connected to the motherboard with black wires facing each other, inside. The various form factors of the power supply such as PC/XT, AT, Baby AT and LPX use a pair of 6-wires connectors known as AT style connectors to connect the power supply to the motherboard.

ATX Power Connectors:
ATX (Advance Technology Extended) Power Connector is a 20-pins connector which outputs 6 types of voltages. ATX style power connectors are used by ATX/NLX form factors.

PIN Signal  Colour1 Colour2
1 3.3 v Orange              Violet
2 3.3 v Orange              Violet
3          Ground Black Black
4 5 v Red Red
5 Ground Black Black
6 5 v Red Red
7 Ground Black Black
8 PW-ok Orange Orange
9 5 v – SB Brown Brown
10 12 v Yellow Yellow
11 3.3 v Orange Violet
12 -12 v Blue Blue
13 Ground Black Black
14 PS – on Green Grey
15 Ground Black Black
16 Ground Black Black
17 Ground Black Black
18 -5 v White White
19 5 v Red Red
20 5 v Red Red

Standard Peripheral Power Connector:
It is also known as “4-pin Molex”. The 4-wire connectors are used by the disk drive power connectors.
Pin Color Description
1 Yellow +12v
2 Black Ground
3 Black Ground
4 Red +5v


Floppy Drive Power Connector:
It also known as mini-plug are used in the 3.5-inch floppy disk drive.

Power Switch:
The older form factor desktop PC/XT cases had the power switch at the back of machine, usually on the right side of case. The switch was actually inside the power supply itself, with a hole cut out in the case. So that it could be reached from the outside.

Power Supply Fan:
It is the primary source to dissipate heat from the entire computer, since the earliest computers. The fan is traditionally located at the rear of the power supply, and special vents are provided for it in the case of the supply itself to allow for it to exhaust. Most fans use +12v power to operate, despite the fact that the wires that run to them are normally red for the +12v line, and black for the ground. The standard size of a computer cooling fan is about 3.25 or 80 mm sq.

Cooling System:
For cooling the system components, drive coolers and baby coolers are used. The drive coolers contain a fan that blows the air and cools the hard disk. They are attached to the hard disk drive using a thermal conductive tape. The bay cooler is also used for cooling the hard disk. the bay cooler has fans to cool the device which is mounted in the "5.25". The hard disk is placed in the bay.

Types of Cooling System:

a) Fan:
The system power supply and the system case contains a fan in it that helps conduit air flow in or out from the system case. This helps in cooling the components located inside the system case and prevents them from being damaged. To cool the microprocessor, you can attach a fan on it.

b) Heat Sink:
A Heat Sink is an object that absorbs and dissipates heat from another object using thermal interns of the computers a heat sink absorbs heat from the processor and the air flowing over the heat sink cools the microprocessor. it is used to cool the microprocessor and other chips on the system.