• Re: ac138

    From Bill Sloman@21:1/5 to Hul Tytus on Sat May 18 01:36:25 2024
    On 18/05/2024 1:15 am, Hul Tytus wrote:
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    Two amps is a bit much for a logic ic. Logic can drive MOSFet gates and
    eight small surface mount MOSFets might work as open collector buffers.
    Back in the day you could an array of this sort of device with a common emitter/source, but I haven't been paying attention in recent years.

    --
    Bill Sloman, Sydney

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  • From Hul Tytus@21:1/5 to All on Fri May 17 15:15:25 2024
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    Hul

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  • From Don Y@21:1/5 to Hul Tytus on Fri May 17 10:58:28 2024
    On 5/17/2024 8:15 AM, Hul Tytus wrote:
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    The '138 is a decoder (demultiplexer). What you are looking
    for is more likely considered a hammer driver. The two
    functions tend not to coexist; if you wanted a low-side
    driver that could handle 8 loads, you would likely be looking
    to drive any *combination* of those loads... an "octal
    driver".

    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.

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  • From Buzz McCool@21:1/5 to Don Y on Fri May 17 11:52:25 2024
    On 5/17/2024 10:58 AM, Don Y wrote:
    ...
    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.


    These four and six channel devices might be close to what Don is talking
    about:

    https://www.infineon.com/cms/en/product/power/smart-power-switches/multichannel-spi-switches-controller/spoc-plus-2-multichannel-spi-high-side-power-controller/

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  • From John Larkin@21:1/5 to blockedofcourse@foo.invalid on Fri May 17 11:59:47 2024
    On Fri, 17 May 2024 10:58:28 -0700, Don Y
    <blockedofcourse@foo.invalid> wrote:

    On 5/17/2024 8:15 AM, Hul Tytus wrote:
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    The '138 is a decoder (demultiplexer). What you are looking
    for is more likely considered a hammer driver. The two
    functions tend not to coexist; if you wanted a low-side
    driver that could handle 8 loads, you would likely be looking
    to drive any *combination* of those loads... an "octal
    driver".

    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.


    There are lots of SPI power drivers, like TPIC6595, but not 6 pins.
    Somebody makes a higher-current 4-channel part.

    Some logic chip could drive a power buffer, like ULN2003. But 8 loads
    at 2 amps each is extreme. Discrete fets make more sense at these
    currents.

    What's the load?

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  • From piglet@21:1/5 to John Larkin on Fri May 17 22:16:44 2024
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Fri, 17 May 2024 10:58:28 -0700, Don Y
    <blockedofcourse@foo.invalid> wrote:

    On 5/17/2024 8:15 AM, Hul Tytus wrote:
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    The '138 is a decoder (demultiplexer). What you are looking
    for is more likely considered a hammer driver. The two
    functions tend not to coexist; if you wanted a low-side
    driver that could handle 8 loads, you would likely be looking
    to drive any *combination* of those loads... an "octal
    driver".

    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.


    There are lots of SPI power drivers, like TPIC6595, but not 6 pins.
    Somebody makes a higher-current 4-channel part.

    Some logic chip could drive a power buffer, like ULN2003. But 8 loads
    at 2 amps each is extreme. Discrete fets make more sense at these
    currents.

    What's the load?



    Wouldn’t it be just one load of 2 amps and seven open?

    --
    piglet

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  • From Hul Tytus@21:1/5 to piglet on Sat May 18 19:23:22 2024
    Yes. One active of 8 at any given time. Aught to be one somewhere.

    Hul


    piglet <erichpwagner@hotmail.com> wrote:
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Fri, 17 May 2024 10:58:28 -0700, Don Y
    <blockedofcourse@foo.invalid> wrote:

    On 5/17/2024 8:15 AM, Hul Tytus wrote:
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    The '138 is a decoder (demultiplexer). What you are looking
    for is more likely considered a hammer driver. The two
    functions tend not to coexist; if you wanted a low-side
    driver that could handle 8 loads, you would likely be looking
    to drive any *combination* of those loads... an "octal
    driver".

    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.


    There are lots of SPI power drivers, like TPIC6595, but not 6 pins. Somebody makes a higher-current 4-channel part.

    Some logic chip could drive a power buffer, like ULN2003. But 8 loads
    at 2 amps each is extreme. Discrete fets make more sense at these
    currents.

    What's the load?



    Wouldn???t it be just one load of 2 amps and seven open?

    --
    piglet

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  • From Hul Tytus@21:1/5 to John Larkin on Sat May 18 19:27:12 2024
    Probably driving valves on & off but a couple other applications are hoovering close by. As piglet mentioned, there is only one on at a time.

    Hul

    John Larkin <jjSNIPlarkin@highnonolandtechnology.com> wrote:
    On Fri, 17 May 2024 10:58:28 -0700, Don Y
    <blockedofcourse@foo.invalid> wrote:

    On 5/17/2024 8:15 AM, Hul Tytus wrote:
    Anyone know of an ic similar to the hc/ac138/238 (16 pin,
    1 input to 8 output multiplexer) but with outputs of the
    open collector/drain style that can handle 2 amps at
    12 volts?

    The '138 is a decoder (demultiplexer). What you are looking
    for is more likely considered a hammer driver. The two
    functions tend not to coexist; if you wanted a low-side
    driver that could handle 8 loads, you would likely be looking
    to drive any *combination* of those loads... an "octal
    driver".

    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.


    There are lots of SPI power drivers, like TPIC6595, but not 6 pins.
    Somebody makes a higher-current 4-channel part.

    Some logic chip could drive a power buffer, like ULN2003. But 8 loads
    at 2 amps each is extreme. Discrete fets make more sense at these
    currents.

    What's the load?

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  • From Hul Tytus@21:1/5 to Buzz McCool on Sat May 18 19:18:47 2024
    Thanks Buzz. looking for a direct connection to keep the timing on simple basis though.

    Hul

    Buzz McCool <buzz_mccool@yahoo.com> wrote:
    On 5/17/2024 10:58 AM, Don Y wrote:
    ...
    You can probably find something automotive that would give you
    8 such outputs in a package (though 8@2A would likely be
    pushing the power dissipation of a normal package) -- but it
    would likely have an I2C or SPI interface, requiring you
    to do the "decoding"/selection elsewhere.


    These four and six channel devices might be close to what Don is talking about:

    https://www.infineon.com/cms/en/product/power/smart-power-switches/multichannel-spi-switches-controller/spoc-plus-2-multichannel-spi-high-side-power-controller/

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  • From Don Y@21:1/5 to Hul Tytus on Sat May 18 18:03:05 2024
    On 5/18/2024 12:23 PM, Hul Tytus wrote:
    Aught to be one somewhere.

    Why? Can you imagine a variety of other applications where a three-bit-code (and ONLY a three-bit-code) would need to be resolved to one of 8 high
    current drives?

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  • From Jasen Betts@21:1/5 to Don Y on Sun May 19 06:03:09 2024
    On 2024-05-19, Don Y <blockedofcourse@foo.invalid> wrote:
    On 5/18/2024 12:23 PM, Hul Tytus wrote:
    Aught to be one somewhere.

    Why? Can you imagine a variety of other applications where a three-bit-code (and ONLY a three-bit-code) would need to be resolved to one of 8 high current drives?

    sprinkler timer, except they usually use AC instead of DC

    --
    Jasen.
    🇺🇦 Слава Україні

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  • From Don Y@21:1/5 to Jasen Betts on Sat May 18 23:43:25 2024
    On 5/18/2024 11:03 PM, Jasen Betts wrote:
    On 2024-05-19, Don Y <blockedofcourse@foo.invalid> wrote:
    On 5/18/2024 12:23 PM, Hul Tytus wrote:
    Aught to be one somewhere.

    Why? Can you imagine a variety of other applications where a three-bit-code >> (and ONLY a three-bit-code) would need to be resolved to one of 8 high
    current drives?

    sprinkler timer, except they usually use AC instead of DC

    Electromechanical ones drive the solenoids directly.

    And, there is no real NEED for an "electronic" unit to
    output a three bit code (plus enable!) instead of 8
    discrete outputs (which also allows multiple zones to
    be active simultaneously, including a "master valve"
    required for ANY of the others to receive water). It's
    easier/cheaper to buy an MCU with a few extra pins.

    [I use three pins per valve: "pull-in", "hold" and "sense"

    Now, where are the "other" applications in that "variety"?

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