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LDO replacement for 7805?

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Krumlink

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I am looking for a replacement for the crappy 7805. For my Binary clock, I am using the 780-05 (the 1.5amp), and it craps out when the voltage reaches about 7volts and I require a extremely smooth voltage because I am using the LS series. It can power my cheapo leds. I am looking for a pin compatable (same pinout) and hookup as the 7805, that has a input voltage at least 6volts. So it will start to fail me at 6 volt input. I am using rechargeable batteries, so that can be pesky. THANKS!

7805!!!!!!!!!!!!!!!! WOOT SN7400!!!!!!!!!!!!!!!!!!!!!!!!!

(just some randomness there)
 
I also would rather it be TI part. I love Texas instruments, they are nice to me. All their chips are good.

I need about 750ma or more. I also need 5 volt. THANKS
 
LM2937 from National will give 500ma at 5V.
The LM2940-50IKCSE3 from Ti will give 1A at 5V
Both are low drop out devices and are pin compatible with the 7805
 
Many low dropout regulators must have a 10uF to 100uF capacitor on their output to ground or they oscillate badly.
Some oscillate if the capacitor has a low ESR and others oscillate if the capacitor has a high ESR.
 
I stuck lots of caps on it to smooth out the voltage since I was dealing with the LS series.
 
I got my samples today (one of each, 3 total) and I am going to test them out.

:)
 
I replaced the 7805 with the new and improved 780M05 Low Dropout regulator. I got it to put out a decent 5v output (4.98 if you want to get technical) when the voltage hit its roof, of about 6.5 volts. ME HAPPY. The binary clock will run much longer with it on there. about how many mA does a average (any/most) TTL LS series chip use? around 20 ma?

I am using 21 LEDS at 8ma

8*21=168ma
10ttl chips*n(ma use)=x
 
TTL LS uses a lot of current. You should have used Cmos because it uses almost no current.

An LED display also uses a lot of current. An LCD uses a very low current but it needs to be lighted when it is dark.
 
sorry for the offtopic but why does TI gives freely all these stuff to everyone that states that studies electronics or works for a company?! :rolleyes:
is it really better advertasing for them?! the transportation costs must be
huge.. with FedEX and UPS...
 
I do study electronics! Im a student in highschool, and they order free samples all the time! I only ordered 1 of 3. Please refrain from making this thread another flame war.

Audioguru, do you think that 750ma is enough for 10 TTL chips and 22 LEDs at 8ma?

I couldnt find compliants for the LS series chips that I was using, but if so, How do I pull more ma out?
 
Besides a Switching Regulator? What about in parallel or whatever. I forgot how it goes.
 
10 LS-TTL chips at maybe 30mA each plus 22 LEDs at only 8 mA each is a total of 476mA. A regulator in a TO-220 case and without a heatsink will be very hot at 2W.
 
It is a D2PAK with a max output of 750ma. If I put them in parallel dont they disapate the heat through them?
 
Krumlink said:
I do study electronics! Im a student in highschool, and they order free samples all the time! I only ordered 1 of 3. Please refrain from making this thread another flame war.

it was just a question my friend...i'm not offending or doubting anybody. :)
 
That's alright, he's just a bit sensitive because he's already been involved in a flame war about free samples.
 
Exactly, and it was 6 pages long...

Now back on topic!!!!!!!!!!!!! (Or I will be mad :mad:)

So do Parallel Regulators Disapate the heat formed by sharing it through them?

If so, my D2PAKs (2 of them) will be sharing the 2W of heat by giving 1W of heat through one, and 1W of heat through the other right?
 
Krumlink said:
If so, my D2PAKs (2 of them) will be sharing the 2W of heat by giving 1W of heat through one, and 1W of heat through the other right?

Probably not (at least not well), one will hog most of the current, get red hot and shut down, the second will then get red hot and shut down as well. Could be an interesting low speed oscillator design?.
 
So what should I do to get the heats out of it?
 
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