16-01-2013, 02:24 PM
Switch Mode Power Supply(SMPS
[attachment=47178]
What is SMPS?
A Switch Mode Power Supply(SMPS) or Switcher is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a source, like mains power, to a load, such as a personal computer, while converting voltage and current characteristics. An SMPS is usually employed to efficiently provide a regulated output voltage, typically at a level different from the input voltage.
Regulation: A feedback circuit monitors the output voltage and compares it with a reference voltage, which shown in the block diagram serves this purpose. Depending on design/safety requirements, the controller may contain an isolation mechanism (such as opto couplers) to isolate it from the DC output. Switching supplies in computers, TVs and VCRs have these opto-couplers to tightly control the output voltage
Precaution: The main filter capacitor will often store high voltage long after the power cord has been removed from the wall. Not all power supplies contain a small "bleeder" resistor to slowly discharge this capacitor. Any contact with this capacitor may result in a severe electrical shock.
APPLICATIONS:
Personal computers
Battery chargers
Househeld appliances
Central power distribution
Vehicles
Consumer electronics
Space station
DISADVANTAGE:
Noise: The spikes can migrate into all areas of the circuits that the SMPS’s power if the spikes are not properly filtered. Additionally the spikes or transients can cause electromagnetic or RF interference which can affect other nearby items of electronic equipment, particularly if they receive radio signals.
Expert design required: It is often possible to put together a switch mode power supply that works. To ensure that it performs to the required specification can be more difficult. Ensuring the ripple and interference levels are maintained can be particularly tricky.
External components: external components are typically required. The most obvious is the reservoir capacitor, but filter components are also needed. These components all require space, and add to the cost.
[attachment=47178]
What is SMPS?
A Switch Mode Power Supply(SMPS) or Switcher is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a source, like mains power, to a load, such as a personal computer, while converting voltage and current characteristics. An SMPS is usually employed to efficiently provide a regulated output voltage, typically at a level different from the input voltage.
Regulation: A feedback circuit monitors the output voltage and compares it with a reference voltage, which shown in the block diagram serves this purpose. Depending on design/safety requirements, the controller may contain an isolation mechanism (such as opto couplers) to isolate it from the DC output. Switching supplies in computers, TVs and VCRs have these opto-couplers to tightly control the output voltage
Precaution: The main filter capacitor will often store high voltage long after the power cord has been removed from the wall. Not all power supplies contain a small "bleeder" resistor to slowly discharge this capacitor. Any contact with this capacitor may result in a severe electrical shock.
APPLICATIONS:
Personal computers
Battery chargers
Househeld appliances
Central power distribution
Vehicles
Consumer electronics
Space station
DISADVANTAGE:
Noise: The spikes can migrate into all areas of the circuits that the SMPS’s power if the spikes are not properly filtered. Additionally the spikes or transients can cause electromagnetic or RF interference which can affect other nearby items of electronic equipment, particularly if they receive radio signals.
Expert design required: It is often possible to put together a switch mode power supply that works. To ensure that it performs to the required specification can be more difficult. Ensuring the ripple and interference levels are maintained can be particularly tricky.
External components: external components are typically required. The most obvious is the reservoir capacitor, but filter components are also needed. These components all require space, and add to the cost.