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Will anything above 1.1v on the reset pin damage the se555 timer? http://www.ti.com/lit/ds/symlink/ne555.pdf
overvoltage to oscillator pin
- Thread starter pager48
- Start date
Daniel Sala
- Joined May 28, 2015
- 65
Hi,
Regarding SE555, no it won't - you can put reset pin at VCC or gnd as most people do, I would guess. I don't have a single damaged SA or SE or NE 555 that has had VCC on the reset pin.
Remember, the 555 is a generic device, doubtful a manufacturer would produce a spontaneously different version with the same nomenclature as all the rest.
Consider the "typical application" schematic on page 4 of the Unisonic datasheet - reset is connected to VCC. The 1V max. on reset only means that at most it would need to be OVER 0.4 to 1V to be operative, UNDER would be low.
It makes sense/becomes clear when you see what the reset input actually is:
Regarding SE555, no it won't - you can put reset pin at VCC or gnd as most people do, I would guess. I don't have a single damaged SA or SE or NE 555 that has had VCC on the reset pin.
Remember, the 555 is a generic device, doubtful a manufacturer would produce a spontaneously different version with the same nomenclature as all the rest.
Consider the "typical application" schematic on page 4 of the Unisonic datasheet - reset is connected to VCC. The 1V max. on reset only means that at most it would need to be OVER 0.4 to 1V to be operative, UNDER would be low.
It makes sense/becomes clear when you see what the reset input actually is:
Attachments
The reset being a PNP with its collector clamped to within a Vbe of ground
has a natural issue to deal with, Vbex, emitter base breakdown if its base is
raised too much above emitter. It has 5K in its emitter, that helps.
Incurring Vbex has been shown to degrade beta in the device under some
processes, as well as effect noise.
But hopefully when Unisonic did device they used same process, geometry,
etc.. such that they conform to the original part or better behavior.
Reghards, Dana.
has a natural issue to deal with, Vbex, emitter base breakdown if its base is
raised too much above emitter. It has 5K in its emitter, that helps.
Incurring Vbex has been shown to degrade beta in the device under some
processes, as well as effect noise.
But hopefully when Unisonic did device they used same process, geometry,
etc.. such that they conform to the original part or better behavior.
Reghards, Dana.
Daniel Sala
- Joined May 28, 2015
- 65
Hi,
What a nightmare thought - e.g. buying a LM324 or a CD4011 by two different manufacturers and them not in fact being the same device as the industry-standard part.
Yes, but you are asking the wrong question(s). Maybe fake parts. Bet you a virtual tea/coffee that not. Generic parts are standard and agreed to be and intended to be drop-in replacements across manufacturers AFAIK. Think about it: if they did such a thing, they'd be sued left, right and centre for ruining companies products.
What a nightmare thought - e.g. buying a LM324 or a CD4011 by two different manufacturers and them not in fact being the same device as the industry-standard part.
ElectricSpidey
- Joined Dec 2, 2017
- 3,334
The value you are looking at in the data sheet is the voltage the chip considers a “low” signal, not a maximum allowable voltage.
