Who is the original & the current manufacturer of the LM2576 IC:

Microchip Datasheet

Onsemi Datasheet

How come there are two manufacturers for the same part? Some of the graphs are different, right? Why does this happen?


3 Answers 3


The original manufacturer was National Semiconductor. The Microchip clone was made by Micrel who was acquired by Microchip ca. 2015.

National Semiconductor was acquired by Texas Instruments ca. 2011.

The onsemi version may be another copy (or seller's choice of more than one copy).

There are other manufacturers such as HGSEMI, HTC Korea and Shenzhen Minos making clones with similar part numbers. And still others such as XLSEMI making similar parts with their own prefix to the part number.

In general, the clones may or may not offer exactly the same performance guarantees (and the 'typical' performance certainly may vary) so you really need to refer to each datasheet individually if you intend on sourcing such 'generic' parts from more than one manufacturer.

As to why it happens, which is somewhat off-topic, my recollection is that the original product offered a market-leading simplicity and ease-of-use (for the day) combined with a relatively high unit price. That is the kind of thing that attracts other manufacturers if the product is (or can be) widely adopted in the industry. Then the $5 part becomes a 25-cent part.

  • 11
    \$\begingroup\$ Another reason is that customers sometimes want parts to be available from several sources in order to better guarantee supply. \$\endgroup\$
    – Finbarr
    Sep 15, 2023 at 16:02
  • 1
    \$\begingroup\$ Yes, sometimes alternate manufacturers are licensed as a second source (in which case, pricing is usually largely unaffected), and sometimes competitors just make their own copies, especially when they can poach the designers from the original company. It's not always clear which is which. \$\endgroup\$ Sep 15, 2023 at 17:39
  • \$\begingroup\$ "Clone" is overly optimistic. I've examined many chip dies, and parts with the same number (e.g. 741 or 555) can have significantly different circuits inside from different manufacturers. (Not just layout changes, but different component values or schematics.) \$\endgroup\$ Sep 16, 2023 at 6:07
  • \$\begingroup\$ @KenShirriff Like the "74HC595" that has beefed up but open-drain outputs (ex. Q7)? \$\endgroup\$ Sep 16, 2023 at 6:49
  • \$\begingroup\$ "the same performance guarantees" can still end up being a disappointment if the original manufacturer (due to improved processes and safety margins) tends to deliver significantly overperforming parts, and the clone not. \$\endgroup\$
    – user107063
    Sep 17, 2023 at 12:51

How come there are two manufacturers for the same part? Some of the graphs are different, right? Why does this happen?

That's pretty much the norm for any part that's old enough and/or had wide-enough adoption. Some parts from even 40+ years ago are still widely used, and if anything the number of second sources is slowly creeping up.

As for why it does happen: mostly due to market demand. Things would be pretty ugly supply-wise if only TI made the 555 chip, just as a simple example.

LM2576 is a rather widely used part - it could even be considered "jellybean" at this point. There are "third" sources for it - clones developed in the last few years, mainly to lower the cost of cheap things that use it. Some of those things are "cheap" only relative to established market players - see e.g. the plentitude of entry-level CNC machines of various kinds, including 3D printers.


How come there are two manufacturers for the same part? Some of the graphs are different, right? Why does this happen?

How come that today's people accept that the fact that a single manufacturer is allowed to control of the supply of basic components of the entire industry? Why does this happen?

As a matter of fact, all of the companies below were the manufacturer of the Intel 8086, either as second-source or clones: Intel, AMD, NEC, Fujitsu, Harris (Intersil), OKI, Siemens, Texas Instruments, Mitsubishi, Panasonic (Matsushita). This was supposedly the norm by the standard back in the day.

There can be three reasons:

  1. Second-sourcing, authorized from the original manufacturer.
  2. Clones, unauthorized but often legal.
  3. Mergers and acquisitions.

Second-Source and Clones

Second-sourcing is responsible for most multi-vendor chips in existence, and it was norm of the industry in the 1970s and 1980s. Back then, most chips in existence were simple. They provided only basic functionality, such as a 4-input NAND gate, a voltage regulator, or an operational amplifier. Rather than one-of-a-kind parts like today's microprocessors, these chips were supposed to be standard interchangeable parts. not unlike diodes or transistors. It would be unreasonable if only a single company makes the LM317 today, just as it would be unreasonable if the 1N4148 small-signal diode has only a single supplier. Thus, allowing one chipmakers to single-handedly control the supply of the lifeblood of an entire industry were seen by many as a risky situation. What if the company starts charging unreasonably high prices? What if a chip shortage occurs? What if the company goes out of business later?

As a result, due to the pressure from chip users, it was customary for a chipmaker to license their designs to one or more 3rd-party companies to produce them independently to ensure to their customers that the chip is "safe" to use, even if it increases their competition. Chips as complex as the Motorola 68000 microprocessors were second-sourced.

The second reason is that, back in the 1970s and 1980s, the technical and legal barrier to reverse-engineering and chipmaking were relatively low. From the legal side, before the Semiconductor Chip Protection Act of 1984 in the United States, chip designs could not be effectively copyrighted. Further, if a chip doesn't invent new circuit or manufacturing technique, but is simply an integrated version of a well-known circuit, it cannot be patented. In addition, model numbers could not be trademarked (which is why Intel switched to the name Pentium instead of 80686). It was legal to inspect a chip under a microscope and create your own with the same patterns, with even the same model number, as long as the chip is legally obtained (for legal details, see my answer at opensource.stackexchange.com) and its manufacturer is clearly represented. From the technical side, the complexity of semiconductor manufacturing back then were relatively simple, only an average level of resource was required for reverse-engineering and manufacturing them. As a result, unauthorized but legal clones were widespread, some of today's biggest U.S. chipmakers started by making second-sourced or cloned chips.

As the complexity of semiconductor manufacturing has exponentially increased, the practice of second-sourcing has become increasingly rare. Today, people have largely accepted the use of single-source chip, even basic components in some cases. Fortunately, since the laws of physics hasn't changed, basic ICs (especially basic analog components) didn't become expotentially more complex. Many chips invented back in the 1970s still see widespread use today, such as National Semiconductor's LM317 linear voltage regulator. Thus, the second-source and clones of these basic components continued to exist. Similarly, new analog components designed today are still sometimes cloned or second-sourced, although it's now less prevalent.

In my opinion, from the perspective of chip users, the practice of second-sourcing played a crucial role to ensure the stability of the semiconductor supply chain, and helped to promote competition. The global chip shortage of the 2020s of basic components like microcontrollers or Power Management ICs should have already retaught people this old lesson.

Mergers and acquisitions

Finally, mergers and acquisitions have become more common in an increasingly consolidated market. For example, here's a partial list:

  • Motorola => Freescale & ON Semiconductor

  • Fairchild Semiconductor => ON Semiconductor

  • Dallas Semiconductor => Maxim

  • Signetics => Philips Semiconductors => NXP

  • Freescale => NXP

  • National Semiconductor => Texas Instruments

  • Linear Technology => Analog Devices

  • Atheros => Qualcomm

  • Intersil => Renesas

  • Atmel => Microchip

Following this trend, one may expect to see a single company called The Semiconductor Company anytime soon now.


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