In 2SD1047 NPN transistor datasheet described the application for power supplies and the description is:

The device is a NPN transistor manufactured using new BiT-LA (Bipolar transistor for linear amplifier) technology. The resulting transistor shows good gain linearity behavior.

  • How do we know which transistors used the "BiT-LA technology"? is it described somewhere in the datasheet?

  • Does it really make a difference between this transistor and for example a general purpose transistor like 2N3055 (I know the packages are different but what about the performance)?

  • Which specifications makes a transistor ideal for using it as main voltage regulating transistor in power supplies?

  • 2
    \$\begingroup\$ It's standard page 1 marketing hype. \$\endgroup\$ – Andy aka May 25 '20 at 15:48
  • \$\begingroup\$ @Andyaka So there's no difference in general? \$\endgroup\$ – ElectronSurf May 25 '20 at 15:50
  • \$\begingroup\$ Have you been to the ST site and looked to see if they list this technology? \$\endgroup\$ – Andy aka May 25 '20 at 15:53
  • \$\begingroup\$ @Andyaka Searching the keyword "BiT-LA" in st.com just shows the 2SD1047 as a single transistor product. \$\endgroup\$ – ElectronSurf May 25 '20 at 15:57
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    \$\begingroup\$ The 2STC5949 also used it but, I think you can assume that given it wasn't a widespread solution to all but the audiophile brigade, then it's marketing hype. Oh, the 2STA2121 uses it too. Same answer, hype. \$\endgroup\$ – Andy aka May 25 '20 at 16:06

Given the flatness of output I_V collector characteristics will affect linearity and power-supply-rejection ability, I'd expect the Early Voltage to be a key parameter for audio power devices.

And the size of the high_current contacts down into the silicon may also matter; this requires slightly larger metallization which requires more silicon. Another way to do this is with additional bond_wires, which definitely increases cost (slightly).



A large EARLY VOLTAGE tells the designer that particular bipolar transistor is a more constant current source as the Vce varies.

  • \$\begingroup\$ What is "early voltage"? \$\endgroup\$ – ElectronSurf May 25 '20 at 17:43

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