Pin-outs compatible with linear stabilisers

State-of-the-art, miniaturised DC/DC pulse converters (switching regulators) ensure perfect efficiency and a wide range of operating parameters. They offer a viable and attractive alternative to classic linear stabilisers (linears). Let us take a closer look at their advantages on the basis of the R-78 product series from the RECOM portfolio.

RECOM is a renowned manufacturer on global markets. For almost 50 years, it has been providing electronic circuit power supply solutions. Its product range includes the R-78 series of switching regulators. They are designed to facilitate modernisation of circuits that were originally equipped with linear stabilisers. Obviously, they can also be successfully used to design and manufacture new equipment. They are distinguished by a wide range of supply voltages, high performance, and thermal tolerance. However, current and output voltage stability remains their overriding advantage.

R-78 switching regulators – general overview

The R-78 switching regulators are pulse-controlled components. They have been designed to replace the well-known LM7805, LM7812, etc. stabilisers. In the majority of the below-mentioned products, the pin-outs are compatible with the sequence and spacing of leads applied in the LM regulators in TO-220 packages (and related products).

One must also note the fundamental advantage that the RECOM products have over linear stabilisers. In the latter, excess energy is dissipated as heat, leading to significant losses. Their mode of operation is suboptimal especially within circuits demonstrating a large difference between the input and output voltage. The capabilities of pulse switching regulators are much more attractive. For example: the 5 V model capable of supplying 1 A current withstands input voltages ranging from 6.5 V to 18 V DC, and its efficiency does not fall below 89%.

The use of such components ensures significant energy savings, which will be of particular importance in battery-powered circuits. It also means that RECOM products significantly mitigate the risk of entire device overheating. Moreover, they come with certain short-circuit protection (SCP) features. The R-78 switching regulators are divided into a number of series, each of which demonstrates certain characteristics, application fields and formats. See below for an overview of individual solutions within this product group.

R-78xx

The R-78 switching regulators whose names come without a letter suffix constitute the basic group of components. They feature power ranging from 0.75 W to 7.5 W, and supply 0.5 A or 1 A current for unregulated voltages in the range from 1.5 to 15 V DC (depending on the model).

R-78AA

Adjustable, surface-mounted switching regulators designed as buck converters, i.e. non-isolated between the input and output. Their power rating is up to 6 W. The output voltage setpoint and input voltages come in wide ranges, with the ratios of 1:3 and 1:8, respectively. The operating parameters are adjusted by means of external components forming a resistive voltage divider. The switching regulator enclosure format allows them to be used in automated, mass-production processes for the manufacturing of electronic devices.

R-78B

The R-78B switching regulators are enhanced R-78xx variants. Their electric parameters have been upgraded, i.e. wider input voltage range (e.g. 4.75–32 V for 3.3 V), better performance (even 97%). They are enclosed in upright-mounted housings, with pin-outs positioned at 90° to facilitate vertical mounting (and in this way obtain a lower circuit profile).

R-78C

R-78C models stand out due to their extended input voltage range (up to 42 V DC) and small SIP3 packages. They are designed for use in equipment that is exposed to significant fluctuations in power supply parameters, e.g. PV monitoring devices.

R-78E

In comparison with other products belonging to the RECOM family of switching regulators, the R-78E models stand out due to their ability to supply rated current (0.5 A) almost immediately after powering up. This feature is important for, e.g. security circuits, in particular, in situations where receivers include such electromechanical components as locks and relays.

R-78HB

The R-78HB switching regulators are designed mostly for industrial applications. Their characteristic features include high supply voltages, so they can operate with high efficiency when connected to a 24 V DC standard line. Similarly as in the case of the R-78AA series, their minimum and maximum V_IN value ratio is 1:8. However, they operate within a higher range (e.g. 9–72 V DC). In conjunction with the efficiency reaching 96%, such parameters enable HB switching regulators to utilise highly effectively the energy stored in battery banks.

R-78S

In contrast to the products described above, the R-78S switching regulators are boost step-up converters. They feature the input range from 0.65–1.3 V to 0.65–3.3 V DC, thanks to which they can operate with such power sources as alkaline, NiCd, NiMH batteries, etc. As they provide extremely stable 1.8 V, 2.2 V or 3.6 V DC voltages, they are compatible with IoT devices, stand-alone Wi-Fi and Bluetooth BLE communication modules, as well as microcontroller-based modules. Their additional features include high performance (93%) and an excellent thermal tolerance range (from -40°C to 100°C).

R-78T

The open-frame R-78T switching regulators supply 1 A current and typical voltages, i.e. 3.3 V, 5 V and 12 V. These components come without enclosures, as they are designed for surface mounting (SMD). Similarly to most LM-78 switching regulators, their pin-outs are compatible with typical LM78 stabilisers, however, they do not require a heat sink. Moreover, they withstand increased current consumption on actuation (up to 1.5 A), which enables them to support inductive and capacitive loads.

R-78W

The characteristic feature of the R-78W series products is that their leads are designed in the form of wires (“W” suffix as in ”wire”). This design eliminates the need to mount switching regulators on PCBs. Therefore, it streamlines their installation in simple devices (powering high-power LEDs, fans, etc.). With no loads connected, the switching regulators consume as little as 1 mA of current, so they are particularly useful in mobile applications with battery and rechargeable power sources.

Text prepared by Transfer Multisort Elektronik Sp. z o.o.