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Small voltage detector

LOL- your title had me thinking of some strange diode invented by an individual named Orring....hmmmkay.

Reply to
bloggs.fredbloggs.fred
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Not really, and most of the ckts proposed here are amplifiers and not comparators.

Reply to
bloggs.fredbloggs.fred

Google says the company is ALD. Such a part would be very useful in my projects, thanks! Another exotica I didn't know about.

Best regards, Piotr

Reply to
Piotr Wyderski

Useful, but there's no free lunch. The transconductance of a MOSFET near threshold is poor; if you need 1/2 mA of output drive and the threshold is at 0V, the output goes low at Vin = 0.5 mA/g_m which (as I read an ALD datasheet) takes 300 mV swing to move the output, and it's gotta be biased +4V from the threshold to get THAT sensitive. Your 'comparator' switches, then, at 4V to 4.3V, not near the 0.0V threshold.

ALD's products are mainly sold in matched-duals and quads, for multitransistor designs.

By comparison, if you can get the biasing right (10 mA quiescent emitter current) a plain old NPN transistor will have g_m of 400 mA/V, and switches 0.5 mA at Vin of 0.600V to 0.6013V...

Either multiple DC supplies, or multiple transistors, are needed to get a zero-volt switch function that's really clean. I liked the old uA742 for a while (long obsolete, but it ran off AC and made its own regulated power).

Reply to
whit3rd

Can the voltage being sensed source AND sink a small amount of current? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

Not just a single transistor, but reasonably temperature stable...

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

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