Uh? That gives you Vout = -Vsat ;-) I want ZERO ±mV's.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
In those rare occasions that I've used split collector PNP's (like in an array), if there's any chance of saturation I put a clamp on it to limit C-B = zero/no-forward-bias.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
That makes Vout = -VBC + Vsatr + VBC = Vsatr, close, but still no cigar.
Fred, You're making it more difficult than need be ;-)
For instance, think 1N4148's, and try again.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Aha! Trick question. The 339 is not like the 311, which has a separate emitter connection for the output.
However, a good analog designer considers what's off the page, including any undefined loads. Since you want to do something with this circuit, let's define a 1k load to ground or to VCC. Maybe some cable or load capacitance, say 200pf.
To do RRO, level shift around +2.5V with a simple resistor string and drive a 74AC14 to take advantage of a bit of hysteresis, although more could be added without worrying about loading the output. If you need to drive 50 ohms or lots of capacitance, tie all the sections in parallel.
Other solutions will need lots more parts, take up valuable board space, cost more, won't drive RRO in both directions, and will probably be slower.
They will be less reliable due to added connections and components, have increased inventory cost and take longer to build. Someone will have to test and troubleshoot in production. Using fast transistors to improve switching speed increases the risk of parasitic oscillation due to stray capacitance acting as a Colpitts, with lead inductance in the base forming the tank. It will probably lack hysteresis and will oscillate on slow risetimes.
Then it has to be documented for internal use or for special customers, and probably include a troubleshooting tree to help manufacturing. It also needs a worst-case tolerance analysis.
How close did you say you wanted to get to the rails?
I did some micropower fire-alarm stuff a long time ago (coded pull stations that mimic'ed the old mechanical clockwork things) and wound up using a resistor-zener-emitter-follower thing.
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
"Joerg" schreef in bericht news:A3zng.72840$ snipped-for-privacy@newssvr11.news.prodigy.com...
each.
But you are throwing away ~80% with a linear regulator, even if Iq was 0. If that 80% wasted consumption didn't bother you, it must have been because there were other much larger loads on the 24 volt, or on the 5V itself. The TPS71550 with it's maximum allowed 24V input is clearly not designed for use in trucks. You can't seriously blame that on the engineers that created it. It's intended use is for handheld gear, with generally much lower battery voltages.
--
Thanks, Frank.
(remove \'q\' and \'.invalid\' when replying by email)
Cheapest I can think of is two diodes and two resistors. If you tweak the resistors to match the current through the diodes then the low level is zero.
Comparator output via resistor to diode with anode on 0V - clamps the voltage at the junction of these two parts to be -0.7V when the comparator is pulling low.
This junction connects to the cathode of another diode with it's anode connected to +5V via a resistor of roughly twice the value of the first one. The voltage at the anode of this diode swings between 0V and +5V.
How close to zero do you want to be? The current in one diode depends on the +ve rail, the other depends on the -ve rail. SwitcherCAD says around +/- 30mv from 0V over 10% supply changes.
I've done it quite often with 1N4148's in a mix of analog processing with digital outcomes.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
The currents don't even need to match very well... 2:1 currents is
18mV deviation from zero.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |
formatting link
| 1962 | I love to cook with wine. Sometimes I even put it in the food.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.