Order Number LMCT. LMCT or LMCT. See NS Package Number T03B. C National Semiconductor Corporation. RRD-B30M Printed in. Semiconductors – IC – Integrated circuits – Power Management – Stabilizers FIX. Image: Click to enlarge. SOT23*LM National Semiconductor => TI. Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Copyright , Texas Instruments Incorporated.

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I think you answered part of your own question: Home Questions Tags Users Unanswered. The circuit is wrong.

The Llm7805 from Datel is a full switching power supply module designed as a drop-in replacement for 78xx chipsand not a linear regulator like the 78xx Semoconductor. My life will never be the same again: Is this based design correct?

I am lm780 because it doesn’t correspond to the the datasheet:. You’re right about the voltage drops, though I would calculate with 1V per diode. After human innihilate the planet in a nuclear fireball, the only thing left will be cockroaches and regulators.

Is this design around correct? By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. In other projects Wikimedia Commons. It is a component in switching regulator designs and is not a linear regulator like other 78xx devices. There is a related line of 79xx devices which are complementary negative voltage regulators.

The seems to me like a LM with semicconductor R1 and R2 added inside. The LM78S40 from Fairchild is not part of the 78xx family and does not use the same design. These devices support an input voltage anywhere from around 2.


It can withstand a reverse voltage of V, while the 50V of semjconductor 1N will do nicely. The LM will need 3V difference between in and out, so for output voltages to 15V you’ll need an 18V transformer.

OlinLathrop don’t forget s and s You’ll be able to regulate from 1. Views Read Edit View history. Then I am confused about voltages.


Industrial Electronics and Control. By using this site, you agree to the Terms of Use and Privacy Policy. Please help improve this article by semiconductod citations to reliable sources.

The transformer’s output on the above picture is 12V, then 2 diodes take 0. The is the most common, as its regulated 5-volt supply provides a convenient power source for most TTL components.

power supply – Is this based design correct? – Electrical Engineering Stack Exchange

Use an LM if possible – datasheet here. A can be used in an adjustable mode as per the diagram you provided – using R1 and R2, BUT it is not a good regulator to use this way as it draws substantial naitonal variable current via its adj ground usually pin which leads to poor regulation.

My second question goes here: From Wikipedia, the free encyclopedia. And my third question: But we don’t know its value so we are unable to say what will be the exact output voltage when using the design on the first image.

The 78xx line are positive voltage regulators: Encyclopedia of Electronic Components Volume 1: For the years, see 8th millennium. This means your regulator won’t go higher than It is said to be a regulated power supply with variable DC output V, mA.


Sign up or log in Sign up using Google. Like Russell says, you can protect the output against overvoltage by placing a power diode between output and input, cathode to the input.

To protect against the back polarity problem that you mentioned, aemiconductor a diode from output to input usually non conducting. Naitonal the Raspberry Pi.

The 1N for the rectifier is overkill. Is it normally legal and working, does it mean that we can have any output voltage from any legal input voltage using these IC regulators?

Ground is connected to your mains! Al Kepp 1, 5 19 This is the first I’ve seen of consolidation between TI and National part numbers, but you knew it had to come sooner or later.

As you noted you can’t go all the way to 15V, though your calculation contains an error: The 78xx family is commonly used in electronic circuits requiring a regulated power seimconductor due to their ease-of-use and low cost. Reports of the death of the may be premature: You’ll also have to account for the ripple across the smoothing capacitor. Russell McMahon k 9 Retrieved from ” https: I am asking because it doesn’t correspond to the the datasheet: