Make Efficiency Matter with the Right Switching Voltage Regulator

Efficiency is paramount when it comes to choosing the right switching voltage regulator. The ability to provide reliable power in a small format is required for today’s miniaturized devices.

A fundamental requirement of electronic design is the ability to generate stable voltages capable of delivering substantial quantities of current. Switching regulators are an essential component for generating stable supply voltages and for translating voltages up or down.

Switching voltage regulators can be called many things: switcher or switch, switched-mode power supply (SMPS), and DC/DC regulators or converters. Popularity continues to grow due to the advantages they offer for more efficient high power conversion requirements, the flexibility of stable output from a single input voltage source, and the ability to accommodate multiple output voltages of different polarities.

The most common switching converter types are:

• Boost, input voltage is stepped up and conditioned for output
• Buck, input voltage is stepped down and conditioned for output
• Buck-boost, input voltage is stepped up or down with negative polarity option
• Flyback, a type of buck-boost that also provides galvanic isolation

Fixed and adjustable linear voltage regulators

For many years, power supply designs relied on linear voltage regulators, which have proven excellent at supplying a continuous fixed voltage output. There are other linear voltage regulators, like the LM317, that are adjustable.

Popular fixed and linear output voltage regulator types are the 78xx positive output and 79xx negative output voltage series. These voltage regulators produce stable output ranging from 5 V to 24 V.

Linear voltage regulators are not switched mode power supplies. Voltage regulators have the advantage of simplicity and low cost. They typically have a power output under 10 W, tend to be less efficient, thereby generating heat, and have low noise and ripple characteristics. Linear regulators only have step-down voltage regulation, whereas an SMPS can provide step-up and step-down and negation of the input voltage using buck, buck-boost, and boost components.

Switched mode power supply systems

Most modern televisions, personal computers, DC motor drives, and power amplifiers require an advanced and efficient SMPS, which utilizes semiconductor switching techniques instead of standard linear methods for providing output voltage. The basic switching converter consists of a power switching stage and a control circuit.

By having lower power dissipation, SMPS has the advantage of higher efficiency by internally switching a transistor (or power MOSFET) between the saturated “ON” and the cut-off “OFF” states.

Buck switching regulators

ROHM Semiconductor BD9x series provides designers with high-efficiency DC/DC buck converters, a compact option for applications requiring efficient power conversion, including automotive and industrial designs. The BD9x series features a simplified design with a reduced component count that saves space and streamlines the manufacturing process. Their low standby current allows for battery life to be extended in portable applications while maintaining stable output voltage for reliable performance, like the BD9A201FP4-LBZTL Buck Switching Regulator (Figure 1).

Figure 1: The BD9A201FP4-LBZTL Buck Switching regulator provides stable output voltage. (Image source: ROHM Semiconductor)

The BD9E105FP4-ZTL Buck Switching Regulator (Figure 2), which features a single, adjustable output, is a direct current regulator specifically designed for lower voltage needs. With low on-resistance power MOSFETs and a single synchronous buck DC/DC converter, the BD9E105FP4-ZTL regulator provides top efficiency in light-load conditions. This is ideal for devices and equipment that demand minimal standby power consumption.

Featuring a good transient response, it offers a small footprint on the PCB while delivering high power density in a small package, perfect for home appliance products like refrigerators and air conditioners, telecommunication devices, adaptors, and secondary power supply equipment.

Figure 2: Lower voltage needs can be accommodated with a BD9E105FP4-ZTL buck switching regulator. (Image source: ROHM Semiconductor)

Boost switching regulators

The MP3414AGJ-Z boost switching regulator has an adjustable output and its thin profile is conducive for a surface mount application where space is limited. It is easily able to perform in a temperature range of -40°C ~ +125°C and can start to operate from an input voltage as low as 1.8 V while providing inrush current and output short-circuit protection (SCP).

The ability to operate in synchronous current mode while maintaining high efficiency is necessary when requiring a step-up converter with output disconnect. Also, there is no need for an external Schottky diode, as the efficiency has been improved with an integrated P-channel synchronous rectifier. The feature for output disconnect when the MP3414A shuts down allows for a complete discharge while drawing a supply current of less than 1 μA while in shutdown mode.

Smaller is better

Fewer external components can be realized utilizing the MP3414A. It uses a 1 MHz switching frequency to allow smaller external components while its soft start feature minimizes external parts count. It can handle wide current load ranges. In addition, the integrated power MOSFET supports peak switching current above 3 A with an output reaching 5.5 V.

This versatility and wide-ranging power in a compact size is ideal with such applications as single-cell Li battery products, including two-cell and three-cell alkaline, NiMH, or NiCd formats. Wireless peripherals, gaming accessories, personal medical devices, and portable media players all benefit from a step-up converter like the MP3414A.

The technology is moving quickly, and it is getting more and more compact. Compared to the SOP-J8, the MP3414AGJ-Z in a TSOT23 package is approximately 72% smaller, allowing for a significantly decreased footprint (Figure 3).

Figure 3: As components are designed smaller and smaller, miniaturization of packaging types like the TSOT23 is necessary. (Image source: ROHM Semiconductor)

Maximizing efficiency while lowering power consumption

The need for miniaturization is a constant driving force, and concurrent to that is the need to maintain reliability and power efficiencies. The BD9E202FP4-ZTL buck switching regulator provides adjustable output and reliable power in a compact design (Figure 4).

Figure 4: The BD9E202FP4-ZTL is a buck switching regulator that delivers reliable power in a smaller, more compact design. (Image source: ROHM Semiconductor)

While there may be a conception that going smaller means sacrificing load capabilities or reliable power delivery, that is not the case. The BD9E202FP4-ZTL does deliver a high conversion efficiency while also contributing to a lower power consumption requirement (Figure 5).

By providing a low standby current, battery-powered devices can benefit from minimal power consumption when they are idle. Also, enabling efficient operation during light loads is achieved through constant on-time control.

Figure 5: Designers look for high-efficiency DC/DC buck converters that can deliver efficiently and reliably. (Image source: ROHM Semiconductor)

Flyback converters for AC/DC and DC/DC

The flyback converter is a buck-boost converter that incorporates a fly-back transformer. It is used in both AC/DC and DC/DC conversion, where there is galvanic isolation between any outputs and the input, and offers the multiplication of voltage ratios with an added advantage of isolation.

An isolated power converter features voltage mode control and current mode control as its two control schemes. In most cases, current mode control should be dominant for stability when operated.

Buck-boost DC-to-DC converters

A typical DC-to-DC converter with an output voltage magnitude greater or less than the input voltage is a buck-boost converter. Generating negative voltages is also possible. It is similar to a flyback converter, but instead of using a transformer, it uses a single inductor. Specifically, a buck-boost converter consists of two different topologies, with both producing a range of output voltages from larger than the input to as little as zero.

Sometimes referred to as “choppers,” DC/DC supplies include a buck-boost circuitry, which functions as either a step-up or step-down converter, depending on the duty cycle.

Conclusion

Efficient power conversion for today’s automotive and industrial designs cannot function without switching voltage regulators. As today’s designs become more compact, the demand for versatile and efficient components that maintain consistent power levels has never been greater.

While switching voltage regulators may fall under different names—SMPS, DC/DC switcher, regulator, or converter—ROHM offers a wide variety of compact options for various applications requiring efficient power conversion.