Power Supply PPT1

Power SupplyPower SupplyPower supply - Internet URLPower supply - Internet URL

http://www.pcguide.com/ref/power/sup/index.htm

1UNIT-2:POWER SUPPLY04/07/23

Purpose of the Power Purpose of the Power SupplySupply

• The Power Supply converts AC The Power Supply converts AC (alternating current) which is external (alternating current) which is external power to DC (direct current) internal power to DC (direct current) internal power that the computer can use.power that the computer can use.

• Convert household power into a form Convert household power into a form the computer can use.the computer can use.

• Power supply is a device that supply Power supply is a device that supply electrical energy to various component electrical energy to various component including motherboard of PC.including motherboard of PC.


WattageWattageRegulationRegulationRippleRippleLoad RegulationLoad RegulationLine RegulationLine RegulationEfficiencyEfficiency

04/07/23 UNIT-2:POWER SUPPLY 3

Characteristics of power supply


• Wattage-It is the total maximum output power that the power supply provides.Typical power ranges from 200W to 500W.

• Regulation-The ability of power supply to control or maintain the output voltage level when the load ie DC output on power supply increases or decreses or when the AC input voltage varies.

• Ripple-Periodic noise in constant output voltage of power supply is called “Ripple”.



• Load Regulation-The ability of power supply to control or maintain the output voltage level when the load ie DC output on power supply increases or decreses.

• Line Regulation-The ability of power supply to control or maintain the output voltage level when the AC input voltage varies.

• Efficiency-The power output divided by total electrical power consumed is called “Efficiency”.


Power ProblemsPower Problems

0V

230V

300V

Normal

Surge

Brownout

blackout

Spike

140V


Power ProblemsPower Problems

• Power ProblemsPower Problems that may lead to power that may lead to power supply problems.supply problems.– Line NoiseLine Noise– SurgesSurges– SpikesSpikes– BrownoutsBrownouts– BlackoutsBlackouts


Line NoiseLine Noise

• Line NoiseLine Noise - Line noise - Line noise consists of small variations in consists of small variations in the voltage level delivered to the voltage level delivered to the computer. the computer.


SurgesSurges

• This is This is a temporary increase of voltage a temporary increase of voltage i.e small over voltage conditions i.e small over voltage conditions that that can last just a few thousandths of a can last just a few thousandths of a second, but in this time the voltage can second, but in this time the voltage can increase from 110 to 1,000 volts or increase from 110 to 1,000 volts or even higher.even higher.

• Excessive Voltage creates overheating Excessive Voltage creates overheating in the supply damage your computer in the supply damage your computer equipment and will destroy it.equipment and will destroy it.


SpikeSpike

• A Spike is a large over voltage A Spike is a large over voltage condition,that occurs in some condition,that occurs in some milliseconds.Heavy equipment like milliseconds.Heavy equipment like drill,presses,grinders and other highly drill,presses,grinders and other highly motorized device can produce tremendous motorized device can produce tremendous power spikes during normal operation.If power spikes during normal operation.If PC is on the same circuitas that of heavy PC is on the same circuitas that of heavy equipment ,the spikes can damage the equipment ,the spikes can damage the power supplypower supply


Brownout Brownout

• BrownoutBrownout - when a brownout occurs, the - when a brownout occurs, the voltage drops from its normal level to a voltage drops from its normal level to a lower voltagelower voltage and then returns; in some and then returns; in some ways, it's like the opposite of a surge. ways, it's like the opposite of a surge.

• i.e.the under voltage condition i.e.the under voltage condition is called is called “Brownout”.high load items draw so “Brownout”.high load items draw so much current that the AC voltage level much current that the AC voltage level drops.under voltage conditions can also drops.under voltage conditions can also damage the power supply.damage the power supply.


BlackoutBlackout

• BlackoutBlackout - A blackout, of course, is - A blackout, of course, is when the power totally failswhen the power totally fails. Blackout . Blackout is a complete loss of electrical power is a complete loss of electrical power where voltage and current drop is a where voltage and current drop is a very low value i.e.0very low value i.e.0.Blackout is usually .Blackout is usually caused by a physical interupption in caused by a physical interupption in the power line due to accidental the power line due to accidental damage by a person or act of the damage by a person or act of the nature.the loss of AC shut down the nature.the loss of AC shut down the computer in milliseconds.computer in milliseconds.


DC DCDC AC

BlockBlock diagram of diagram of SMPS

Bridge RectifierAnd Filter

Switching Transistor Transformer

PULSEWIDTHMODULAITION

Optoisolator

Fullwave Rectifier

AC MAINS SUPPLY

DC output

Reference volatge

filter

Comparator


SMPSSMPS((Switch Mode Power SupplySwitch Mode Power Supply))


• The Bridge Rectifier The Bridge Rectifier converts The AC converts The AC input voltage into DC voltage.input voltage into DC voltage.

• The FilterThe Filter removes ripple at the output removes ripple at the output voltage.voltage.

• The Switching Transistor The Switching Transistor converts the DC converts the DC voltage into square wave AC.voltage into square wave AC.

• The Transformer The Transformer step down the voltage.step down the voltage.• This AC square wave is rectified This AC square wave is rectified by a full by a full

wave rectifier.wave rectifier.

SMPSSMPS((Switch Mode Power SupplySwitch Mode Power Supply))


SMPSSMPS

• Th DC output which ripples from Th DC output which ripples from the rectifier is the rectifier is filtered by a filterfiltered by a filter..

• The DC output voltage is The DC output voltage is compared with a reference voltage compared with a reference voltage by a by a comparator.comparator.

• The error voltage at the The error voltage at the comparator output is fed to comparator output is fed to the the Pulse Width Modulation,Pulse Width Modulation,


SMPS Output Voltages

Voltage Current Application/Use

+5V 2.3A All logic chips CMOS

-5V 1A -VCC for DRAM

+12V 1A Drive motors DRAM

-12V 1A Serial Port 17UNIT-2:POWER SUPPLY04/07/23

• Power switches to the power supply have Power switches to the power supply have changed over time. changed over time.

• AT connectorAT connector– added a remote switch on – added a remote switch on the front of the computer connected to the front of the computer connected to the power supply in the back.the power supply in the back.

• ATX/NLX connectorATX/NLX connector – uses an electric – uses an electric switch connected to the motherboard switch connected to the motherboard that uses a feature called Soft_Power to that uses a feature called Soft_Power to turn on the computer.turn on the computer.

Motherboard Power ConnectorMotherboard Power Connector



• Most important Most important connection.connection.

• Supplies power Supplies power to other devices to other devices through the through the motherboard.motherboard.

• Wires are made Wires are made of copper.of copper.

ATX 20 pin

Older P8 & P9

Or P1 & P219UNIT-2:POWER SUPPLY04/07/23

P8 P9

ATX AT



AT connectorAT connector

• The AT power connector provides DC The AT power connector provides DC output on two 6-pin connectors i.e. P8 output on two 6-pin connectors i.e. P8 and P9,connected to the and P9,connected to the motherboard.motherboard.

• Carry +5V,-5V,+12V,-12V voltages Carry +5V,-5V,+12V,-12V voltages and PW-OK signal ie power good and PW-OK signal ie power good signal,is a signal indicating that the signal,is a signal indicating that the output voltages are stable and usable output voltages are stable and usable by the CPU.by the CPU.


ATX connectorATX connector

The ATX power supply provides 5 voltages to the motherbard:The ATX power supply provides 5 voltages to the motherbard: +5V+5V -5V-5V +12V+12V -12V-12V +3.3V+3.3V

Through a 20 pin connector.Through a 20 pin connector.

The 3.3V supply is added to support the broad use of lo-The 3.3V supply is added to support the broad use of lo-voltage logic.voltage logic.

It has 3 special signals :It has 3 special signals :

1)PS-ON 2) 5 VSB 3)PW-OK1)PS-ON 2) 5 VSB 3)PW-OK22UNIT-2:POWER SUPPLY04/07/23

ATX connector

• -12V: Used for some types of serial port.

• PS-ON: is an input to SMPS.only when this signal

s low,the SMPS output should be ON.otherwise,the output should be OFF.

• PW-OK: is a power good signal.


ATX power connectorATX power connector

• 5 VSB: The 5 VSB is a standby voltage which

supplies power to special circuits,when the SMPS and the system are OFF.

• -5V: used for compatibility with older

hardware.used with floppy controller.


Protection DevicesProtection Devices

• To run computer system properly,it To run computer system properly,it require a steady power supply with require a steady power supply with clean and noise free power.clean and noise free power.

• It acheives through protection It acheives through protection devices.devices.

• 2 types of protection devices:2 types of protection devices:

1)circuit Breaker1)circuit Breaker

2)Surge suppressor2)Surge suppressor25UNIT-2:POWER SUPPLY04/07/23

circuit Breakercircuit Breaker

• A circuit breaker is an A circuit breaker is an automatically operated electrical automatically operated electrical switch designed to protect an switch designed to protect an electrical circuit from damage electrical circuit from damage caused by overload or short caused by overload or short circuit.circuit.


Surge suppressorSurge suppressor

• A surge suppressor also called “surge A surge suppressor also called “surge protector”,is a device,used to prevent protector”,is a device,used to prevent damage to electronic equiment from damage to electronic equiment from voltage “spikes” called transients.voltage “spikes” called transients.

• Is a small box with a power supply and 3-Is a small box with a power supply and 3-wire chord for plugging. wire chord for plugging.

• The immediate threat of damage to your The immediate threat of damage to your electrical components and equipment by electrical components and equipment by high voltage transients, spikes, and surges high voltage transients, spikes, and surges would be eliminated. would be eliminated.


UPSUPS((Uninterruptible Power SupplyUninterruptible Power Supply))

• WHAT IS AN UPS?WHAT IS AN UPS?

• An Uninterruptible power supply (UPS) is An Uninterruptible power supply (UPS) is also also known as a battery back-upknown as a battery back-up, which provides , which provides emergency power to the connected equipment emergency power to the connected equipment by supplying power from a separate source by supplying power from a separate source when power is not availablewhen power is not available


GENERAL PURPOSE UPSGENERAL PURPOSE UPS


BASIC COMPONENTS OF UPS


Block diagram of UPSBlock diagram of UPS

Line filterAnd Transformer

Rectifier Inverter DC to AC

Battery charger

Load

Filters

AC MAINS SUPPLY

Battery

Static switch

230V

Static switch

AC MAINS Section


UPSUPS

It consist of following functional block:It consist of following functional block:

AC mains section(filter,transformer AC mains section(filter,transformer and rectifier)and rectifier)

Inverter and FilterInverter and FilterBattery charger circuit and BatteryBattery charger circuit and BatteryStatic SwitchStatic Switch


UPSUPS

• AC mains section:AC mains section: When AC main supply is applied,it has pass When AC main supply is applied,it has pass

through line filter and transformer.The through line filter and transformer.The rectifier rectifies AC.rectifier rectifies AC.

• Inverter and filter:Inverter and filter:This circuit work with power or without This circuit work with power or without power.when power is there it delivers constant power.when power is there it delivers constant 230 v output to the load.230 v output to the load.


UPSUPS

• Battery charger circuit and Battery:Battery charger circuit and Battery:

The Battery charger converts input AC supply to The Battery charger converts input AC supply to the desired DC level and charges the the desired DC level and charges the battery.Battery provide the backup if blackout battery.Battery provide the backup if blackout

occursoccurs..• Static Switch:Static Switch:

If power failure occurs,the invertor is connected If power failure occurs,the invertor is connected to load with the help of static switch.This to load with the help of static switch.This inverter changes DC from from battery to AC.inverter changes DC from from battery to AC.


Types of UPSTypes of UPS

• There are 2 types of UPS:There are 2 types of UPS:

ONLINE UPSONLINE UPSOFFLINE UPSOFFLINE UPS


OFFLINE UPSOFFLINE UPS

TransformerRectifierAC to DCFilter

Electronic Switching

Inverter DC to AC

Battery charger

Battery

AC Mains supply

230V

•It is a standby power supply.•In this type of UPS,Battery is charged when AC mains are ON and as soon as AC mains are OFF,battery discharges and supplies power to PC.•Switching is invloved.


ONLINE UPSONLINE UPS

• It is main power supply.It is main power supply.• Battery is continuously charged and then Battery is continuously charged and then

delivers DC power to inverter.delivers DC power to inverter.• Switching is not involved.Switching is not involved.

TransformerRectifierAC to DCFilter

Inverter DC to AC

Battery charger

Battery DC

AC Mains supply

230V


Difference Between On-Difference Between On-Line and Off-Line UPSLine and Off-Line UPS

On-line UPS Off-line UPS

1)It is main power supply

1)It is standby power supply

2) Battery is continuously charged and then delivers DC power to inverter.

2) Battery is charged when AC mains are ON and as soon as AC mains are OFF,battery discharges and supplies power to PC.

3)Switching is not involved.

3)Switching is invloved


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Power Supply PPT1