The latest SMPS combine good efficiency with attractive pricing

Continuously evolving technology has kept manufacturers on their toes as they are now coming up with new products to meet emerging requirements for enhanced efficiency and even better performance

By Kartiki Negi

Thursday, February 27, 2014: A switch mode power supply (SMPS) is an electronic device that uses a switching regulator to efficiently convert electric power from a source (AC mains) to the load by changing the current and voltage characteristics. Unlike a linear power supply, the pass transistor of an SMPS continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimises wasted energy.

SMPSs are the replacements for linear regulators as they offer higher efficiency and come in a smaller size and lighter weight. Ideally, switching regulators dissipate no power. Voltage regulation is achieved by varying the ratio of the on-to-off time. A linear power supply, on the other hand, regulates the output voltage by continually dissipating power in the pass transistor. So, this higher power conversion efficiency is an important advantage of a SMPS. It is also considerably smaller and lighter than a linear supply due to the smaller transformer size and weight.

There are various types of SMPSs available in the Indian market. These include desktop computer SMPSs, SMPS adapters for laptops, SMPS-based battery chargers, and the SMPSs used in medical appliances, PLC controllers, and in industrial applications such as motors, LED lighting, etc.

The latest in the market

Nippon India launched the new Meanwell boost-type DC/DC constant current LED drivers~LDH-45 series. The new drivers possess 9~18V DC input for LDH-45A-X models and 18~32V DC input for LDH-45B-X models.

“Both series feature 350mA/ 500mA/700mA/1050mA output current. In addition, the LDH-45 series has the built-in PWM and analogue dimming functions; thus, the on/off remote control and the output current adjustments can be done by connecting the external PWM signal or 0.25~1.3V DC analogue voltage, which cater to the needs of lighting fixtures that are designed to incorporate various energy-saving dimming features,” says Anil Joshi, managing director, Nippon India.

Nuteck Products has introduced the SD120 (24 V, 5 A) SMPS. “The product can cater to electrical control panels, PLC panels and medical devices, and offers features such as 100 per cent full load burn in tests and a universal AC input supply range with working range going upto 440 AC, which is the USP of the product,” says Rajesh Doultani, managing director, Nuteck Products.

In November 2013, EOS Power India launched its M(W)LT450 series of medical and commercial u-channel AC/DC products, which come with the special interleaved PFC feature. This range caters to the demand for high peak loads in all weathers for motors, the extended temperature range required for outdoor applications or the need to operate in hazardous environments. “Our M(W)LT450 series is used in a wide array of medical equipment including the MRI, X-Ray, CT and PET scanners, blood analysers, DNA equipment, patient monitors, ultrasound equipment, robotic surgical devices, heart-lung machines, diagnostic equipment and automated pharmaceutical dispensers,” says S G Thube, deputy manager, EOS Power India.

In October 2013, Digital Promoters introduced its RS series of SMPSs ranging from 15 W to 150 W. “The product meets the stringent EMS EN50082-2/EN61000-6-2 heavy industrial levels, as it complies with electromagnetic compatibility standards, that is, non-interference with other electronic devices,” says Anil Sood, director, Digital Promoters.

Technological advances

Continuously evolving technology has kept manufacturers on their toes. They are now coming up with technologically advanced SMPSs that meet new requirements, enhance efficiency and enable the working of different products. The SMPSs of today are more cost-effective. They include high voltage MOSFETs, control ICs and silicon carbide diodes for PFC and PWM stages, as well as low voltage MOSFETs for synchronous rectification. These products support low power consumption. They also offer extremely low on-state resistance and low capacitances. Today’s SMPS also combines good efficiency with attractive pricing.

The recently launched DH-45 series of Nippon India has an extremely high efficiency of up to 95 per cent and can operate between -40~+70°C of ambient temperature with only free air convection. All models in the series are potted to provide heat dissipation, while being dust and moisture resistant. Besides, they offer two options in input/output packages like pin style or wire style. With a built-in EMI filter, these LED drivers comply with the EMI requirements mandated by EN55015 lighting regulations, without connecting any external EMI restraint components. Other standard functions include short circuit, over voltage, and input under voltage protection. Suitable applications include street lighting, landscape lighting, tunnel lighting, household lighting, and all kinds of off-grid LED garden lights or LED streetlights that are powered by solar chargers.

EOS Power’s latest launch M(W)LT450 series of products particularly cater to customers who are energy conscious. “Our standby power consumption limits are below the requirements for open frame AC/DC power supplies with maximum values of 0.5 W and 0.8 W, respectively, at 115 V AC and 230 V AC inputs. It is one of the smallest-sized open frame AC/DC product in the market with class 1 options. With forced air cooling, the WLT450 can deliver in excess of 450 W,” explains SG Thube.

Another key specification for customers powering motors or capacitive loads is the peak power capability. The M(W)LT450 series can deliver up to 475 W for 24 V and 30 V; and 500 W for its 48 V model for only 5 seconds maximum, which can be crucial in such applications. Besides, it has no minimum load requirement and has voltage adjustability via an onboard pot and a 5 V standby output at 2 A. It comes with EN60601 third edition and EN60950 second edition approvals, respectively.

The RS series is highly efficient and has a long life. Load power consumption is not extremely low, that is, <0.5 W. Electrolytic capacitors currently being used have a long life with a 105º Celsius rating in 100 per cent full load burn-in tests. “However, Indian manufacturers have not been able to keep pace with the latest in SMPS technology and have been left far behind,” says Anil Sood.

Buying tips

Before making a purchase, customers should be clear about what kind of product they actually require the SMPS for. One must be assured about some of the factors such as performance and efficiency. Going for well-known players with a good brand name is highly recommended.

If it is to be fitted in range, go for an SMPS that offers optimal performance, optimal efficiency, best power factor, low no load power, low output ripple and highest quality PSUs. Some other things that you should look out for while buying an SMPS are wattage, amperage and efficiency (depending on your requirements), warranty and cost. Buyers should look into aspects like input voltage, regulation, output voltage and output current.

Larger, heavier units are preferable to lightweight models. Higher-quality power supplies almost always use bigger and better capacitors, chokes and other internal components, and they come outfitted with larger heatsinks for superior heat dissipation—all of which translates into more weight. Larger cooling fans, which typically move more air while making less noise than smaller fans, are another plus point.

You should check the PSU connectors to confirm the unit is compatible with your system. Also check power output and rails, besides efficiency.