Application Notes

Order a DC-DC Converter

AC to DC Switching Power Supplies

Switching power supplies, sometimes referred to as SMPS power supplies, switchers, or switch mode power supplies, regulate the output voltage using a complex high frequency switching technique that employs pulse width modulation and feedback. Acopian’s switching power supplies also employ extensive EMI filtering and shielding to attenuate both common and differential mode noise conducted to the line and load. Galvanic isolation is standard in our switchers, affording our users input to output and output to ground isolation for maximum versatility. Switching regulated power supplies are highly efficient, small and lightweight, and are available in both AC-DC single and wide-adjust output and DC-DC configurations. Our Low Profile wide adjust output switching power supplies can be voltage or current regulated and are externally programmable.

Why use switching power supplies?
Switching power supplies are smaller, lighter, and more efficient than linear power supplies. For example, a 250Watt linear power supply would require 600 in3 of mounting space and weighs 26 lbs, while a comparable ac-dc switching power supply would require 60 in3 of mounting space and weighs 2 lbs. Linear power supplies have efficiencies in the 40%-60% range, while switching power supplies fall in the 70%-90% range. This means less power wasted as heat, thus a lower operating cost.

What is a wide adjust output power supply?
Typical power supplies have a fixed output voltage with an adjustable range of ± 0.5volts. Wide adjust output power supplies are continually adjustable over the whole output range, from 0 volts to rated output voltage. Acopian makes ac to dc power supplies in both styles, with our low profile switched mode wide adjust power supply having an output voltage and current adjustable with an internal screwdriver pot or an external 0-10VDC or 0-5VDC signal. Options are available for remote adjustment through an Ethernet, RS232, RS485 or USB connection.

Do Acopian power supplies require a minimum load for proper regulation?
No. All Acopian power supplies are internally pre-loaded. DC output voltage regulation will be within specifications from 0% load to 100% load.

What is a universal input?
A typical power supply has a fixed AC input and must be ordered with either a 115VAC or 230VAC input. Acopian’s low profile and narrow profile switching power supplies come with a universal input, accepting 90-265VAC, 49-420HZ, or 110-350VDC. This allows for maximum flexibility and minimum spares especially when designing a system to be used both in the United States and overseas.

What is power factor correction?
Most electrical devices, such as power supplies, have an inductive component to their AC inputs which results in a power factor of less than unity (1). This means that the volt-amp (VA) rating of the power generating device must be higher than the actual Watts being consumed. This raises the cost of generation to utilities because they have to supply VARS, which do no work, along with the Watts. Acopian’s low profile and narrow profile switching power supplies are designed with an electronic power factor correcting input, which brings the power factor to near unity (typically .99). Many utilities charge a “power factor penalty” to industrial users and using Acopian’s power factor corrected switch mode power supplies will reduce operating costs.

What is a current regulated power supply?
Typical power supplies are voltage regulated, which means that the output voltage will remain constant throughout the output current range. Acopian’s low profile switched mode wide adjust power supplies can be voltage regulated or current regulated, depending on the load and power supply settings. For example, imagine a 10VDC, 5A power supply with a connected load that draws 3A at 10V. If the Vadj and Iadj pots are fully clockwise, the power supply will regulate the voltage at 10VDC and the output current will be 3A. If the Vadj pot is slowly turned counterclockwise, the output voltage will track the pot setting. If it is left at 5VDC, the output will remain at 5VDC and the current will be reduced to 1.5A. Current regulation mode is different. Leave the Vadj pot fully clockwise and turn the Iadj pot counterclockwise. When the Iadj reaches 3A, the power supply will start to current regulate. As the Iadj pot is turned lower, the output voltage will start to decrease to maintain the current that the Iadj pot is set at. If it is left at 2A, the output current will remain at 2A, the output voltage adjusting to the voltage required to keep it at 2A (6.7V in this case).

What is a programmable power supply?
Wide adjust power supplies typically have adjustment potentiometers (pots) mounted on the power supply to adjust the output voltage and current. Acopian’s low profile switching power supplies are wide adjust and can also be programmed remotely. Our standard units can be remotely programmed with a 0-10VDC external programming voltage (0-5VDC optional). That means that the output voltage and current can be remotely “set” by an analog output from a PLC, computer, or other control device. Our 1U and 1400Watt units, as well as our special custom power systems, can also be remotely programmed using Ethernet, RS232, RS484 or USB interfaces. This means that the user interface can set the output voltage, output current, and power supply enable. Also, the output voltage, output current, and power supply status can be monitored through this interface.

Can switching power supplies be paralleled for a higher current output?
Acopian’s low profile switching power supplies, when ordered with the “P” option, can be paralleled for a higher output current. Up to four units can be connected in parallel to obtain a maximum 2880 watts. Through Acopian’s unique “Sbus” connection, the power supplies will actually share current.

Can switching power supplies be connected to provide a redundant output?
Acopian’s low profile switching power supplies, when ordered with the “N” option, can be connected (up to four units) for an N+1 redundant output. N+1 redundancy means that there is one more power supply connected than the load actually requires, and that even with the loss of one power supply, the load will continue to function normally. For example, if a load requires 15A to operate properly, connect four (4) 5A power supplies in parallel. If one power supply fails, there will still be 15A available.

What is soft start?
All power supplies have an inductive component to their front end circuitry. When power is applied, the power supply will momentarily appear as a short circuit to the AC line and can draw many times its full load amps, causing unwanted circuit breaker trips. Acopian’s low profile, gold box, and narrow profile switchers are designed with an electronic “soft start” circuit that will reduce the inrush to a value that can be accommodated by “D” curve circuit breakers.

AC-DC switching power supplies (Mini Encapsulated)

AC-DC switching power supplies (Narrow Profile)

AC-DC switching power supplies (Low profile)

AC-DC switching power supplies (Gold Box)

DC-DC converters (Mini encapsulated)

DC-DC converters (Narrow profile)

Typical applications for switching power supplies:

Click here to view a table that compares a
switching power supply vs. a linear power supply vs. an unregulated power supply.

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