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P2 Power amplifier - Page 3 — Parallax Forums

P2 Power amplifier

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  • I'm back to the IR2101 because you can use more motors with different connections and operating principles.
    I have put the latest status in #001.

  • jmgjmg Posts: 14,692

    @pic18f2550 said:
    I'm back to the IR2101 because you can use more motors with different connections and operating principles.
    I have put the latest status in #001.

    The risk of such a simple 'low IQ' driver, with a H Bridge load, is you can turn on both FETS at once, and there is no driver protection against crowbar currents during normal switching.

    There are newer drivers, that have proper FET hand-over sense inside the driver, and that can support 3 states. Hi Side, Lo Side and Floating (catch diodes only)
    Some even include auto-free wheel, where they sense a FET in diode mode, and keep the gate on until the current reverses.
    If you want drive freedom, a gate driver that allows 100% duty, is also going to be useful.

  • Yes, I know.
    The IR2104 is a representative of the one you are talking about.
    But it's not a problem for me because the upstream power supply units absorb it and the FET can withstand 50A, pulse-wise it can do even more.

    By the way, they are only half H-bridges that are connected to the respective motors.
    In this way, everything from simple plunger coil drives, as used for laser focusing, to complex linear drives, as used in passenger lifts, can be interconnected.

    :) The P2 is perfectly made for this. :)

  • jmgjmg Posts: 14,692

    This is an example of modern packaging and ratings possible
    https://www.edacafe.com/nbc/articles/1/1838249/Alpha-Omega-Semiconductor-Unveils-High-Performance-Smart-Power-Stage-SPS-Family

    In a single 5x6 package, you get 30V / 60A of Gate Driver plus 2 FETS, with Temperature and Current feedback signals.
    Peak current capability, up to 150A for 10us and 100A for 10ms

  • 30V max is already 100%, there are no reserves.
    Self-destruction would be pre-programmed.
    Another problem is that I cannot generate measurement pulses of 1μs with it.

  • jmgjmg Posts: 14,692
    edited 2021-05-30 03:14

    and more MOSFET news, these at 40V and showing just how resistance is so low, heatsinks can be omitted in most designs.

    https://www.nexperia.com/about/news-events/press-releases/Low-RDS-on--40-V-MOSFETs-from-Nexperia-deliver-highest-power-density-for-Automotive-and-Industrial-applications.html

    Measuring just 8 x 8 x 1.7 mm, the new power MOSFETs also feature class-leading linear mode / safe operating area (SOA) characteristics for safe and reliable switching at high current conditions. SOA at 1 ms, 20 VDS operating conditions is 35 A due to a combination of silicon and package, while at 10 ms, 20 VDS where the package dominates, SOA is 17 A. These figures are 1.5 - 2x better than the competition. The devices also offer the best single pulse avalanche rating (EAS) at 2.3 J and very strong ID current rating of 500 A, which – unlike some competing devices – is a measured rather than theoretical limit.

    Suitable gate drivers can drive these fast enough.

    VDS = 30 V; RL = 1.2 Ω; VGS = 10 V; RG(ext) = 5 Ω
    d(on) turn-on delay time 40 ns
    tr rise time 33 ns
    td(off) turn-off delay time 117 ns
    tf fall time 48 ns

    ..

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