Re: voltage drop from 555 / 556

On Fri, 3 Jun 2005 09:52:46 -0400, the renowned "Lyle"
<walshlgNOSPAM@xxxxxxxxxxxxxxxxxx> wrote:

>I'm playing with designing an IR tracking system using IR LED's flashed from
>a 556. I want to run it off of a 9 v battery and was trying to calculate
>the right resistor for high output but I can't find specs for output voltage
>drop under load. I may just have to manually graph it out but by chance,
>does anyone know what kind of voltage drop below Vcc I can expect out of a
>555 or 556 at 100 - 150 mA max load?
>thanks
>Lyle

If you read the data ***, it says Voh for sourcing 100mA on a 15V
supply, 13.3V typical, 12.75V minimum. At 200mA, 12.5V typical.

So, one guess would be 1.7V drop at 100mA and 2.1V at 150mA. Assuming
you're talking about the bipolar type. Be sure to bypass the battery
well.

If you use a transistor such as a 2N4401 wth 15mA of base drive, the
drop will likely be less than a couple hundred mV.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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