In typical electronics design, an engineer chooses a single DC-DC converter for each necessary supply voltage. A high availability and low price option is typically chosen to avoid supply risks. However, most bills of materials still have the risk of this single part going out of stock, into obsolescence, or rising in price. This risk is usually tolerated because of the difficulty in finding pin-to-pin replacements for DC-DC switching regulators. Like many semiconductor products, both proprietary packaging and pinouts make finding footprint matches time consuming and expensive. In addition, DC-DC switching converters have ranged electrical parameters, like input and output voltage, which can make parametric searches difficult to conduct. In this article, the current process of finding DC-DC switching regulator IC cross-references is discussed, and an automated method of generating these cross-references is introduced.
How to Cross-Reference Two DC-DC Switching Regulator Components
In order to show the cross-referencing process, one part from Texas Instruments and one part from STMicroelectronics will be compared. Typically these two parts would have to be found in a manufacturer cross-referencing list or in a distributor parametric search. An engineer starts with the original part and tries to find parts with similar characteristics. In this example, the Texas Instruments MC33063ADRG4 and the STMicroelectronics MC34063ABDTR will be investigated to see if they are compatible. These are control circuit ICs for step-up (boost), step-down (buck), and voltage inverting applications.
Depending on the process used, the engineer may check the footprint compatibility or the electrical compatibility first. Comparing footprints can be a challenging process; in this example, the Texas Instruments part describes its package as ‘SOIC (8)’ while the STMicroelectronics part describes its package as ‘SO-8.’ An engineer will know that these two footprints are the same, but this text difference makes searching for the two parts difficult. Once footprint compatibility has been determined, the pinout must be compared. This is usually done by visiting the datasheets of both parts. Here it can be seen that both parts have the same pin functionality.
Now that the mechanical properties of the two parts have been shown to be equal, the electrical properties must be crossed. Both parts will output between 3 and 40V, and take as input 1.25 to ~40V (38V for the STMicroelectronics part. The two parts have a 1.5A rated current and 100kHz switching frequency. Both parts feature an operating ambient temperature range of -40 to 85 Celsius. The ICs are designed for non-synchronous converters, meaning that only a single control signal is output. The two parts also support the same switching regulator topologies, leading to the conclusion that, for many circuit operating points, these two regulators will be compatible.
Using the SourcingBot Cross-Reference Tool to Automate the DC-DC Switching Regulator Cross-Referencing Process
Because the cross-referencing process is so time consuming and expensive for engineers to perform, it is often ignored for semiconductor products. Engineers must select from only a few trusted suppliers and a limited range of parts. However, the cross-referencing tool at SourcingBot automates much of the work, meaning that an engineer can assemble a list of cross-references, even for semiconductor components, faster than ever. SourcingBot compares all of the important specifications for DC-DC switching regulators, including package, number of pins, input and output voltage ranges, rated current, topology, synchronicity, output configuration, number of outputs, and operating temperature range.
The process of finding cross-references using the SourcingBot tool is easy; to start, just type a part number into their search bar at sourcingbot.com and information about the part will be loaded. Technical specifications, pricing, availability, and matched products are shown. The match table shows the most important specifications, including input and output voltage ranges, and the matches are ranked by a transparent similarity score, given out of 100 percentage points. All of the latest products from top linear voltage regulator manufacturers are compared, making it easy for engineers to assemble their cross-reference lists quickly and reliably. To see the match comparison between the two parts in the previous section, check the part page for the STMicroelectronics part on the SourcingBot website: https://sourcingbot.com/semiconductors/integrated-circuits-ics/pmic/voltage-regulators—dc-dc-switching-regulators/stmicroelectronics/mc34063abdtr
The SourcingBot website can also cross-reference an entire bill of materials automatically. Just visit their tool at sourcingbot.com/xref-tool and upload a bill of material to get started. It can return replacements from all manufacturers or from a given list of manufacturers. In addition to voltage regulators and other semiconductor products, SourcingBot can calculate cross references in many passive component categories, including resistors, capacitors, and inductors, as well as many connector categories, including circular connectors, terminal blocks, FFC and FPC connectors, and more.