Use a Modular Platform with Robust Components to Simplify Consistent DC/DC Regulator Evaluation

DC/DC switching regulators are fundamental to power delivery in a broad array of applications, yet choosing the optimal topology and supporting components for a specific design remains a significant challenge. Designers have typically faced a time-consuming process that requires separate evaluation boards and inconsistent test setups to meet the requirements for board space, efficiency, thermal performance, and electromagnetic interference (EMI).

What designers need is a structured evaluation approach that speeds power stage selection by enabling direct comparison of multiple converter topologies under consistent, repeatable test conditions. Equally important, that approach must build on robust passive and interconnect components that exhibit stable behavior from one sub-module to the next, so differences in measurements reflect the regulator and inductor choices rather than the test infrastructure.

This article discusses the challenges of regulator design and evaluation. It then introduces components from Würth Elektronik and shows how they enable reliable DC/DC converter evaluation by providing a stable foundation for a modular platform designed by Microchip Technology.

Why is direct regulator comparison hard with conventional methods?

In evaluating a DC/DC switching regulator for a new design, engineers face multiple decisions involving regulator topology and operating characteristics. In practice, the application typically drives topology choice for a step-up (boost), step-down (buck), or constant-current LED driver stage. For each regulator type, the target operating environment brings a combination of broad requirements for input voltage range, output voltage, and load current, along with specific needs for features such as quiescent current, undervoltage lockout (UVLO), output disconnect, pulse frequency modulation/pulse width modulation (PFM/PWM) operation, and protection mechanisms.

Along with these requirements, regulator selection is further complicated by the need to balance the interdependent challenges associated with constrained board space, efficiency, thermal performance, and EMI. Constrained board space drives selection toward smaller passives and tighter layouts, which may degrade performance. Efficiency and thermal behavior under real load current require characterization to confirm that the regulator and its passives can sustain the application's duty cycle without unacceptable temperature rise. EMI behavior often only becomes visible late in the evaluation cycle, when layout, switching frequency, and inductor characteristics have already been fixed.

Conventional evaluation practice typically addresses each candidate regulator on its own dedicated board, each with its own layout, connector style, and passive component selection. This approach makes it difficult for designers to directly compare different regulator types and assess their operating characteristics. Furthermore, rather than spending time evaluating regulators, designers find themselves assembling multiple prototypes, which ultimately complicates direct comparison of results, slowing the evaluation cycle as pressure mounts to maintain tight product schedules.

Based on a portfolio of Würth Elektronik components, Microchip's BB22H52A Building Block Solutions Switchers (BBS-SW) board is a modular evaluation platform created specifically to help designers efficiently assess multiple DC/DC switching regulator configurations under consistent test conditions.

Meeting challenges of DC/DC regulator evaluation through a consistent platform

Microchip's BB22H52A BBS-SW board (Figure 1) addresses the evaluation challenge through a modular architecture that places seven independent DC/DC converter sub-modules on a single printed circuit board (pc board). Each sub-module implements a different switching regulator with its own input and output terminals, enable (EN) network, and dedicated passive component set, while sharing a common board layer stack, ground reference, and connector convention.

Figure 1: The BB22H52A BBS-SW places seven independent DC/DC converter sub-modules on a single board with a common layer stack, enabling direct evaluation under matched test conditions. (Image source: Microchip Technology)

The seven sub-modules represent three distinct topology classes and span input voltages from 1.5 V to 50 V, output voltages from 3.3 V to 24 V, and output currents from 100 mA to 1 A (Figure 2). Feature sets include low quiescent current (I_Q) battery operation, programmable UVLO, and constant-current LED driving.

Figure 2: The BB22H52A sub-modules span input voltages from 1.5 V to 50 V, output voltages from 3.3 V to 24 V, and output currents from 100 mA to 1 A. (Image source: Microchip Technology)

Two boost regulators, BBS1 (MCP16251) and BBS3 (MCP16411), target low-voltage, low-current rails typical of battery-powered designs. Two MCP1663-based boost regulators, BBS4 and BBS5, generate higher 12 V and 24 V rails from low-voltage inputs. The evaluation board also includes a synchronous buck regulator, BBS2 (MCP16311), a non-synchronous buck regulator, BBS7 (MCP16331), and a constant-current LED driver, BBS6 (MCP1664).

Across all sub-modules, the platform maintains a consistent evaluation infrastructure. Standardized 2.54 mm terminal connectors handle all inputs and outputs. Each sub-module's EN pin is pulled high through a resistor by default, allowing power-up by applying input voltage. The same EN pin convention also supports shutdown mode evaluation through a single connection. Test points and accessible measurement nodes simplify voltage, current, and ripple characterization.

The uniformity of the modules provides designers with a common reference from one sub-module to the next, enabling them to run identical test sequences across topologies and confidently assess the differences as regulator and inductor related, rather than board-level disparities. Achieving these evaluation goals relies on both a consistent platform architecture and a set of robust components, particularly inductors that are well-matched to the demands of each converter topology.

Matching converter topology demands with robust components

Across the BB22H52A, Würth Elektronik inductors, terminal blocks, ceramic capacitors, and thick-film resistors populate the seven sub-modules. The Würth WR-TBL terminal blocks provide the common 2.54 mm input/output convention discussed earlier. Drawn from a portfolio spanning Class 1 and Class 2 dielectrics, Würth multilayer ceramic chip capacitors (MLCCs) handle input filtering, output filtering, and decoupling across each sub-module. Rated for +155°C operation, Würth WRIS-RSKS thick-film resistors serve as feedback dividers, sense resistors for current monitoring, and pull-up references. These component families provide a stable foundation for the platform's consistent behavior across sub-modules, isolating regulator and inductor differences as the remaining variables in the evaluation process.

Among these passive components, the inductor is typically regarded as the most application sensitive. It directly shapes efficiency, thermal behavior, the EMI signature, and the board footprint. Inductor selection criteria differ across topologies, so the Microchip board provides designers with options by drawing on three WE inductor families: WE-MAPI, WE-XHMI, and WE-MXGI.

In a buck converter, the inductor sets the output current ripple while interacting with the regulator's slope compensation and switching frequency. In a boost converter (Figure 3), the inductor sits at the regulator's switching node, and its average current scales with the output-to-input voltage ratio, with peak current rising further with ripple. Microchip's design guidance for the MCP1663 recommends 4.7 µH for output voltages below 15 V and 10 µH for output voltages of 15 V and above, mapping directly to the Würth Elektronik 7443844020047 4.7 µH inductor on the 12 V-output BBS4 and the 744393305100 10 µH inductor on the 24 V-output BBS5.

Figure 3: The MCP1663 typical boost application places the inductor at the regulator's switching node, with the inductance value selected to match the target output voltage. (Image source: Microchip Technology)

Across topologies, inductance value drives a fundamental tradeoff. Higher inductance reduces ripple current and core losses but increases physical size and DC resistance (DCR). Construction also matters, with magnetically shielded inductors recommended for electromagnetic compatibility (EMC) critical applications to prevent uncontrolled coupling with neighboring traces and components. All three Würth inductor families on the BB22H52A are magnetically shielded, and each addresses a different combination of size, efficiency, and EMI tradeoffs.

The WE-MAPI inductors on BBS1, BBS2, and BBS7 use a compact magnetic alloy core with self-shielded construction. The family is AEC-Q200 qualified, and Würth's comparison reports cite a 17 to 28% lower total power loss than other parts in a 24 V to 12 V buck stage at 2 A and 500 kHz. A high-temperature variant, rated -55°C to +150°C, is used on BBS1, extending the qualification margin for harsh-environment designs.

The WE-XHMI inductor on BBS5 employs a flat wire coil with a composite core that lowers DCR and increases saturation current (ISAT). These characteristics directly support the higher inductor current and tighter thermal margins required by the 24 V boost stage.

The WE-MXGI inductor on BBS3, BBS4, and BBS6 is built on an iron alloy material optimized for switching frequencies beyond 1 megahertz (MHz), with ultra-low DCR and AC losses. These properties allow a single part to serve effectively in both the boost (BBS3, BBS4) and LED driver (BBS6) topologies. The molded construction also delivers tight unit-to-unit consistency that lets lab measurements continue to hold true across full production runs.

Together, these three inductor families address the three interdependent challenges that complicate DC/DC regulator evaluation:

• WE-MAPI targets board-space-constrained sub-modules and features shielded construction that reduces unwanted radiation and coupling for improved EMI characteristics.
• WE-XHMI provides the current and thermal margin needed at higher output voltage and load.
• WE-MXGI brings the high-frequency loss profile and stability that allow one inductor family to serve multiple topologies and translate lab evaluation results into volume production.

Combined with the broader Würth passive portfolio, the three inductor families give the BB22H52A its consistent evaluation behavior across topologies.

How the seven sub-modules illustrate key design tradeoffs

Beyond enabling cross-topology comparison, the BB22H52A's regulator selection highlights specific design tradeoffs that recur within each topology class. By placing same-output and same-IC variants side by side on a single board, the platform lets designers see how feature depth, output configuration, and topology choice each impacts regulator behavior.

The two low-voltage boost sub-modules, BBS1 and BBS3, both regulate to 3.3 V from a nominal 1.5 V input but offer significantly different feature sets. The MCP16251 on BBS1 emphasizes battery longevity through its true load disconnect option and a quiescent current of 4 µA in PFM mode. The MCP16411 on BBS3 instead emphasizes richer monitoring and protection at a similar 5 µA quiescent current.

The high-voltage boost sub-modules, BBS4 and BBS5, share the same MCP1663 regulator but generate 12 V and 24 V outputs, respectively, illustrating how the output configuration determines the maximum load current available from a single regulator. The MCP1663 is non-synchronous, so each sub-module includes an external Schottky diode, demonstrating a specific component-count tradeoff, compared to the synchronous boost on BBS1.

The two buck sub-modules are AEC-Q100 qualified and illustrate the classic synchronous-versus-non-synchronous tradeoff. The MCP16311 on BBS2 is a synchronous buck with up to 30 V input and 1 A output, achieving high efficiency without an external rectifier. The MCP16331 on BBS7 is a non-synchronous buck that extends the input range to 50 V at the cost of an external Schottky diode and lower output current.

BBS6 relies on a different approach in which the MCP1664 LED driver regulates output current rather than voltage, driving up to eight white LEDs in series. Open-load protection and PWM dimming complete the LED-specific feature set.

Speeding evaluation and the transition to custom solutions

Fully assembled and tested, a BB22H52A sub-module, such as the BBS1 (Figure 4), enables designers to begin evaluation by connecting an external power source to the input terminals and a load to V_OUT and GND. As noted earlier, the regulator powers up as soon as the input voltage is applied. With the supply on, a voltmeter at V_OUT confirms the regulated output, which remains very close to the nominal output, even as the input voltage and load vary.

Figure 4: To begin evaluation of the BB22H52A BBS1 sub-module, designers need only connect a laboratory power supply, voltmeter, and load. (Image source: Microchip Technology)

Beyond evaluation, the BB22H52A serves as a reference design for building custom DC/DC converters. It is supported by complete schematics for all seven sub-modules, a four-layer pc board layout, and a bill of materials (BOM) based on readily available Microchip regulator ICs and Würth passive components.

Conclusion

Selecting the right DC/DC switching regulator for a new design challenges engineers to balance topology choice, board space, efficiency, thermal performance, and EMI behavior. The BB22H52A BBS-SW helps address these challenges through a modular evaluation architecture that builds on a robust Würth Elektronik component portfolio, including three inductor families matched to each topology's specific demands, along with terminal blocks, ceramic capacitors, and thick-film resistors.