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7406 vs MUN5235DW

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josip:
Hi,

On old digital (0V/5V) bus interface with two or more devices for output is used 7406 (out is pulled high by 1kohm). I need 4 signals, not 6. For 7406 (variation) minimum size AFAIK is SOIC. I prefer to use 2 MUN5235DW (Dual NPN BRT) instead. Is there anything (that I don't see) why 7406 is much better part (than MUN5235DW) for this?

Regards,
Josip

David Hess:
The 7406 and 74LS06 are faster.  There is a reason On Semiconductor does not specify switching speed of the MUN5235DW.

josip:

--- Quote from: David Hess on February 27, 2024, 03:18:36 pm ---The 7406 and 74LS06 are faster.  There is a reason On Semiconductor does not specify switching speed of the MUN5235DW.

--- End quote ---

OK, I can check switching speed with scope for both with identical setup.

MrAl:

--- Quote from: josip on February 27, 2024, 01:05:51 pm ---Hi,

On old digital (0V/5V) bus interface with two or more devices for output is used 7406 (out is pulled high by 1kohm). I need 4 signals, not 6. For 7406 (variation) minimum size AFAIK is SOIC. I prefer to use 2 MUN5235DW (Dual NPN BRT) instead. Is there anything (that I don't see) why 7406 is much better part (than MUN5235DW) for this?

Regards,
Josip

--- End quote ---

Hello,

The 7406 input is made to interface with TTL and the logic levels associated with those kinds of outputs.  You'd have to check if the transistor package can work with that kind of input reliably over the expected temperature range.

The output of the 7406 is fairly fast, with fast rise and fall times.  The propagation time is very low also, and this would beat the bipolar solution by a long shot when the input goes low because bipolars can have a nasty storage time which can stretch the time out into the microseconds rather than the nanoseconds unless you use an anti-saturation clamp diode(s), which can, unfortunately, increase the logic low output.

What this means then is it depends on what the 7406 is being driven by and what it has to drive.  The levels and the timing have to match if any of those specs are important to the application.  Without knowing the application it's not possible to say for sure so you'd have to check that.

What all that means is that the transistor can replace the 7406 in some applications and not others so you'd have to do some careful testing.  If this is for a large production run I'd be very, very, careful.

josip:

--- Quote from: MrAl on February 27, 2024, 06:39:04 pm ---Hello,

The 7406 input is made to interface with TTL and the logic levels associated with those kinds of outputs.  You'd have to check if the transistor package can work with that kind of input reliably over the expected temperature range.

The output of the 7406 is fairly fast, with fast rise and fall times.  The propagation time is very low also, and this would beat the bipolar solution by a long shot when the input goes low because bipolars can have a nasty storage time which can stretch the time out into the microseconds rather than the nanoseconds unless you use an anti-saturation clamp diode(s), which can, unfortunately, increase the logic low output.

What this means then is it depends on what the 7406 is being driven by and what it has to drive.  The levels and the timing have to match if any of those specs are important to the application.  Without knowing the application it's not possible to say for sure so you'd have to check that.

What all that means is that the transistor can replace the 7406 in some applications and not others so you'd have to do some careful testing.  If this is for a large production run I'd be very, very, careful.

--- End quote ---

Logic signal for input (7406 or transistor base) is from 3.3V micro controller pin (few milliamps). 7406 or transistor are "shorting" to ground, signal pulled high (5V) by 1k resistor. I found that in similar setup as mine, was used bsv52 (in datasheet there is 10-20 ns turn-on-off time and this is fast enough). So I guess that I should take 74ls06. Digital is my area, not analog, probably is better to not make simple things more complicated.   

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