Electronics > Projects, Designs, and Technical Stuff
SMD alternative to TIP31 and TIP32
mikerj:
--- Quote from: Yansi on November 09, 2019, 04:37:57 pm ---
--- Quote from: mikerj on November 09, 2019, 03:48:47 pm ---
--- Quote from: Yansi on November 09, 2019, 12:52:24 pm ---Why do you use linear bipolar transistors for 5V SWITCHING application?
--- End quote ---
As opposed to the digital bipolar transistors, or the digital MOSFETs? Bipolar transistors are still widely used for switching, why do you believe this makes no sense?
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Why the hell would one even consider a poor linear BJT for a LOW VOTLAGE SOLENOID SWITCHING application in almost 2020, where you leave half (I am exaggerating) the load voltage across the saturated BJT?
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Why do you keep emphasising linear BJT? Exactly what other kind of BJTs do you think there are?
--- Quote from: Yansi on November 09, 2019, 04:37:57 pm ---Tell me, where are BJTs used for switching these days? In a four decades old legacy designs, or in twenty or more years old dumb power ICs, that likely should not be even considered to new designs?
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Obviously all these semiconductors companies offer a wide range of bipolar switching transistors purely for their own amusement, there can be no other explanation can there?
Yansi:
TIP31 is not a switching transistor, it is a (poor) linear amplifier. Quite unsuitable for switching applications. (Even though it may be fast enough for a solenoid)
There are different types (whole product lines) of BJTs intended for switching applications, optimized for much lower Vcesat and faster switching times.
What I want to say is that I would look for a very different BJT (than TIP31), if that much you (or anybody else) needs a BJT SWITCHING application.
T3sl4co1l:
I mean, they certainly found them suitable back in the day. Nothing wrong with that.
But arguing semantics is rather useless without any further input from the OP.
Tim
langwadt:
--- Quote from: v8dave on November 09, 2019, 05:14:44 am ---With the massive number of transistors on the market, I am looking for anyone who has done this and what options they chose.
I have a design that drives servo valves at 5V and max 500mA current.
The current design us all through-hole but I need to rework this to SMD to get it smaller. This uses the standard TO220 TIP31 and TIP32 and I'd like to use an SMD transistor instead. As these devices don't have any direct replacement for SMD use, has anyone got any experience of swapping these out for SMD parts?
I have a working simulation in Tina and this works with real hardware too so I can easily plug in the values from the SMD parts and make sure that it works, simulation wise at least.
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servo and npn+pnp does that mean linear control and not switching?
mariush:
I wonder if it would be possible to use darlington arrays like ULN2003A : http://www.ti.com/lit/ds/symlink/ulq2003a.pdf
They're 500mA per "channel" but you can parallel multiple inputs to get the higher current, so you could do for example 2 x 3 channel and leave the 7th unused.
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