hybridfree/eevblog-posts huggingface dataset:
LM40001G datasheet - Page 1
Forum section: electronics / projects

author: Unknown
author_rank: Unknown
timestamp: July 06, 2013, 04:29:10 am
content: I got an LM40001G at the surplus place today for $5. This is a 400x64 LCD display, should be interesting trying to drive it as it has no intelligence whatsoever - the data has to be driven in and latched. Glad that I ordered another Arduino Mega 2560 today (Sain Smart has them cheap!)Anyway, the datasheet is really hard to find, almost impossible, but with a little sleuthing, I found one. It's getting attached here so that it's not so hard in the future. Enjoy.Do you think we should have a "datasheets" subcategory or file repository? I'd love to have a centralized repository for the hard to find or really useful ones.

author: amyk
author_rank: Super Contributor
timestamp: July 06, 2013, 11:03:50 am
content: It helps to spell its part number correctly... according to Google there's no such thing as an LM14001G but the first result forLM40001Gis the datasheet.Expensive part too.

author: Unknown
author_rank: Unknown
timestamp: July 06, 2013, 02:08:24 pm
content: Fixed.

author: Unknown
author_rank: Unknown
timestamp: July 06, 2013, 02:40:13 pm
content: Quote from: amyk on July 06, 2013, 11:03:50 amHah, you're right. The funny thing is, it's really hard to find if you search for "LM40001G datasheet".
LM1881 Remove Sync from Video Output - Page 1
Forum section: electronics / projects

author: paul_g_787
author_rank: Frequent Contributor
timestamp: November 04, 2019, 08:12:59 pm
content: Hi everyone.I am making my own RGB cables for my games consoles and have been using the LM1881 to strip sync.I have a question regarding the PlayStation 2. The signal is sync on green. So, I take the green signal to the input of the LM1881 and the clean sync output to SCART pin 20 (composite in).The problem with this however is that there is still a sync signal present on the green pin. How would I clean the green signal to remove the sync leaving just the video?Basically the opposite of the LM1881.Ideally a solution with as little components as possible because it needs to fit inside the SCART connector.
LM25085 switching frequency - Page 1
Forum section: electronics / projects

author: luiHS
author_rank: Frequent Contributor
timestamp: June 10, 2019, 11:10:55 am
content: Hello.I replaced the switched regulators XL4015 and XL4016 in all my circuits, for an LM25085. I used the Texas configurator, leaving the default value for the switching frequency at 454.966 Khz.I have had a problem, although I think I have already found out the error. When connecting the circuit, to 12 volts of input, the voltage of the power supply began to vary, in addition when approaching the ear to the board a noise is heard, and although the output voltage is stable at 5 volts, it affects the operation of the circuit that feeds. If the input voltage goes up to 18 volts for another of my circuits, the problems practically disappear. Checking the scheme on the Texas web, in the input capacitor puts 15uF, but today seeing it carefully, I see that it puts 3 units, I mean 3 capacitors of 15uF in parallel and not one as I thought.In my circuit I put 3 capacitors of 10uF, and that because in one of the calculations the capacitor was 22uF, with a lower switching frequency. As the ceramic capacitors in 0402 to 25v, they are not bigger than 10uF, I decided to put 3 thinking that I was still putting a larger capacity capacitor. The reality is that for this calculation the total capacitor should be 3 x 22uF, that is 66uF.I have not tried to put a couple more capacitors in parallel, to get to 50uF, but I hope that is the solution to the problem.One question:The LM25085 can be configured for a switching frequency between 100Khz and 800Khz.What is the ideal frequency, advantages and disadvantages of choosing a higher or lower value? What I see is that for higher frequencies the inductor is of a lower value, which means that it would be smaller and probably cheaper.
LM25148 DC-DC Converter Current Feedback RC Filter Value........  - Page 1
Forum section: electronics / projects

author: Smokey
author_rank: Super Contributor
timestamp: November 28, 2023, 01:06:45 am
content: https://www.ti.com/lit/ds/symlink/lm25148.pdfCheck out this app note from TI for the LM25148.Page 16:https://www.ti.com/lit/ug/snvu773a/snvu773a.pdfR11 is the current feedback resistor. 5mOhm sets the overcurrent trip at about 10A. All good here.R17 at 49.9Ohm and C34 at 33pF make an RC lowpass at 96.6MHz.http://sim.okawa-denshi.jp/en/CRtool.phpThis seems crazy high. The switching frequency of the converter only goes up to 2MHz.Is this a mistake or is there a reason to have the current feedback filter set that high?

author: moffy
author_rank: Super Contributor
timestamp: November 28, 2023, 10:20:59 am
content: The resistor and capacitor R17/C34 are not used in the typical application on page 32 of the datasheet, they are probably there for glitch removal i.e. spikes present on the switching edges and do not form part of the control loop, if that is their reason, then you would want them well outside the control loop frequency so that they don't compromise stability.

author: fourtytwo42
author_rank: Super Contributor
timestamp: November 28, 2023, 11:33:06 am
content: Refer to data sheet 9.2.1.2.4 Current-Sense Resistance para 5 "The CS-to-output propagation delay " you will see the effect of CS pin delay's such as this RC network upon peak inductor current, that is why the values are small.The reason for the RC network is switching noise falsely triggering the comparator, normally there will be blanking circuitry within to ignore this but if the switching noise is severe some external filtering might also be required hence the additional RC.The amount of external filtering required is external component (particularly mosfet) and layout dependent.As noted in the data sheet any delay on the CS pin should be minimized.
LM2576 Constant Current Circuit - Page 1
Forum section: electronics / projects

author: aiq25
author_rank: Regular Contributor
timestamp: November 16, 2021, 07:03:51 pm
content: Hi. I was looking online and found an interesting design with a LM2576 constant voltage/constant current power supply design but I'm a bit confused on how the constant current part works and I was wondering if someone can help explain it.Attached is the schematic. Here is the link to the project:https://www.pcbway.com/blog/technology/How_to_build_an_adjustable_switching_power_supply_using_LM2576_.htmlI wanted to do a variant with this design but use an MCU for the control. I understand how the voltage regulator works but confused about the current regulation.

author: Benta
author_rank: Super Contributor
timestamp: November 16, 2021, 08:46:01 pm
content: So...Where's the load?And what do four 0.5 ohm resistors in parallel connected to ground at both ends do?And...No, I won't continue.

author: sleemanj
author_rank: Super Contributor
timestamp: November 16, 2021, 08:57:36 pm
content: In short, the 4 parallel resistors are the current shunt, the opamp applies a higher voltage to the feedback of the lm2576 when the current increases above the setpoint, this "fools" the lm2576 into thinking the output voltage is too high so it reduces it, thereby reducing the current, and at some point equilibriam is found.Take careful note of GND and LGND in the schematic, same symbol but different things.

author: aiq25
author_rank: Regular Contributor
timestamp: November 16, 2021, 08:58:53 pm
content: Quote from: Benta on November 16, 2021, 08:46:01 pmThose are the current sense resistor. The load is connected between "Vout" and "LGND".QuoteNo problem. You don't have to continue. Thanks for responding.

author: John B
author_rank: Frequent Contributor
timestamp: November 16, 2021, 09:02:51 pm
content: The current sense resistors are connected between LGND and GND, so the load isn't regular GND referenced. The op amp compares the voltage at LGND to the inverting input. The output will be ~0V which causes the LM2576 to increase it's duty cycle, hence increase the output voltage and current and therefore increase the voltage at LGND until it reaches equilibrium. The op amp will have around 1.8V on it's output, which is approximately a diode drop plus the ~1.2V reference on the LM2576. I guess R7 sets the constant current, and R6 is some trimmer, which also gives the diode D2 a discharge path.

author: sleemanj
author_rank: Super Contributor
timestamp: November 16, 2021, 09:13:19 pm
content: Quote from: John B on November 16, 2021, 09:02:51 pmThe diode prevents this. This is a cv/cc circuit, cc only kicks in when the trigger is reached.Quote from: John B on November 16, 2021, 09:02:51 pmR6 is the CV trimmer, it sets the voltage in absense of the CC limiting it (by pushing feedback higher).

author: John B
author_rank: Frequent Contributor
timestamp: November 16, 2021, 09:38:55 pm
content: I meant the output of the op amp would be 0V as an initial condition until the loop takes control of the LM2576.
LM2576 Waveform - Page 1
Forum section: electronics / projects

author: dan3460
author_rank: Frequent Contributor
timestamp: May 02, 2017, 04:52:40 pm
content: I'm using a LM2576 5.0 to power a project. This is the first time that I have use that chip. From this power supply I have a LM350 that gives me a 3.3V supply, on the project there are parts that need 5V and 3.3V. After building this thing on a proto board I'm only get 4.89V, the only load that I have so far is the LM350 and its ancillary circuit.I put the scope at the output pin on the LM2576 (pin 2) and I get the form shown below. I followed the circuit described on page 19 ofhttp://www.ti.com/lit/ds/symlink/lm2576.pdfthe only difference is the diode which I used a 1N5819.Is the waveform shown below, normal. It seems to me that there is a lot of ringing. The square wave part is running at about 54kHz, the ringing at about 1.31Mhz. The top of the square wave is at 11.75V. The Vin is 12V.

author: Benta
author_rank: Super Contributor
timestamp: May 02, 2017, 05:15:53 pm
content: It's normal. It happens when it's running with no load (or almost no load).More precisely, it happens when there is no continuous current through choke. If choke current drops to zero, it will ring at the choke's parallel resonant frequency, which is the inductance in parallel with the parasitic capacitance between the windings (plus some smaller parasitics).Give it a load larger than half choke peak-peak ripple current, and all will be fine.

author: David Hess
author_rank: Super Contributor
timestamp: May 02, 2017, 06:52:41 pm
content: I agree; that looks like the normal discontinuous conduction waveform which occurs at low output current.There are various ways to solve that if it is a problem including adding a snubber or increasing the inductance.
LM2576 - Worth to download the updated datasheet - Page 1
Forum section: electronics / projects

author: atferrari
author_rank: Frequent Contributor
timestamp: November 18, 2014, 08:07:04 pm
content: Datasheet revised on 2013 by TI.Wonder if it will work with Win 8.1..."To further simplify the buck regulator design procedure, National Semiconductor is making available computer design software to be used with the SIMPLE SWITCHER line of switching regulators. Switchers Made Simple(Version 3.3) is available on a (3 1?2") diskette for IBM compatible computers from a National Semiconductor sales office in your area."

author: Bored@Work
author_rank: Super Contributor
timestamp: November 18, 2014, 09:16:28 pm
content: Quote from: atferrari on November 18, 2014, 08:07:04 pmWell, that update in 2013 was probably just the intern slapping a TI title page in front of the old Nat Semi datasheet. And one with a different page size, so reading all the old Nat Semi datasheets became a pain. I.e. the intern was in general incompetent and gave a rat's ass.But the blame also sits with the old Nat Semi, where they didn't manage to update their datasheets for donkey's years. Nat Semi moved Simple Switcher to web-only long before TI picked up their remains.
LM2586 step up problem - Page 1
Forum section: electronics / projects

author: IO390
author_rank: Regular Contributor
timestamp: February 13, 2014, 07:27:21 pm
content: I've built the circuit attached to this post. The inductor is hand wound on an amorphous core, and measures just under 32uH.When I first turned on the circuit, I had the current limit set to 500mA and it instantly went up to the limit.When the inductor is removed but all the other components left in place, the circuit draws about 120mA.Can anyone think of a reason as to why this is? The schottky diode hasn't yet arrived, so I substituted it with a 1N4007. This being said, when I remove the diode but leave the inductor in place, the circuit pulls the PSU to the current limiter. Is this just because the inductor is hand wound, or is maybe saturating?Thanks in advance.

author: free_electron
author_rank: Super Contributor
timestamp: February 13, 2014, 08:04:24 pm
content: Quote from: IO390 on February 13, 2014, 07:27:21 pmnot normal ...Quotethat 1n4007 is so slow it will never come out of conduction !Quoteyou essentially cut off the feedback so the switcher keeps pumping because it doesnt see an output voltage : eventually it saturates the core.As for the hand wound inductor .... i wouldn't trust that as far as i can throw it. do you know the magnetic properties of that core ? did you calculate the saturation current for your hand wound inductor ?

author: IO390
author_rank: Regular Contributor
timestamp: February 13, 2014, 08:05:58 pm
content: Thanks for the reply. I'll get a proper inductor and try again.
LM2587 from National - ebay fakes? - Page 1
Forum section: electronics / projects

author: 0xFFF0
author_rank: Regular Contributor
timestamp: March 23, 2023, 07:10:10 pm
content: Boost converters are sold with the LM2587 from National for $2-3 on ebay. At Mouser, these chips from TI cost $10. Is that a ebay fake chip?

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 23, 2023, 07:30:28 pm
content: It may be a coincidence, but in a previous life that exact same component gave us a major headache.After sending the component for a failure analysis, it was determined to be fake.A thorough investigation revealed that our board assembler had purchased the chip from a Chinese broker.I know, I know: advice from a web forum is not ironclad expert opinion. Therefore, and depending on the dollar amount of the purchase, and/or the liability you will face if the device fails, that the devices are sent to a third party lab for analysis. They can scan for evidence of blacktopping, leads wetting or corrosion, going even to decaping and micro-photographing the die. They can also check the packaging conditions.

author: thm_w
author_rank: Super Contributor
timestamp: March 24, 2023, 12:10:09 am
content: Almost guaranteed.The silkscreen on these:- looks weird:https://www.aliexpress.us/item/3256803474462595.html- clearly sanded off:https://www.aliexpress.us/item/2251832476995353.htmlIts probably the same as the LM2596(?) where they are using an equivalent part from XLSemihttps://datasheet.lcsc.com/lcsc/1809050422_XLSEMI-XL1509-5-0E1_C61063.pdf

author: barshatriplee
author_rank: Regular Contributor
timestamp: March 24, 2023, 06:53:23 am
content: e-bay is not really a dependable source for components. We gotta buy at our own risk.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 24, 2023, 11:00:07 am
content: nuff said, you pay for what you getdont expect a 1-2$ part to be equivalent ? unless some miracle happening ?Aliexpress, Ebay and others "cheap" priced sources ...

author: peeper
author_rank: Newbie
timestamp: October 26, 2023, 09:19:17 am
content: I am in Hong Kong, China. If you have a part you want to find, you can try to ask me to help you find it and sell it to you at the lowest price.
LM2596 inductor selction - Page 1
Forum section: electronics / projects

author: MarkC
author_rank: Newbie
timestamp: July 24, 2025, 07:24:18 am
content: I need to select an inductor for a LM2596 but the load will vary from about 100mA to about 1.3A. Input is 24V from the 3D printers main PSU and output will be a fixed 12V.From the datasheet, it is clear I need a 100uH inductor for 1.3A but what will happen when the load is really low?Thanks for any guidance.

author: Benta
author_rank: Super Contributor
timestamp: July 24, 2025, 10:22:49 am
content: The LM2596 is perfectly happy to only deliver partial load current. No probs.

author: MarkC
author_rank: Newbie
timestamp: July 24, 2025, 05:42:47 pm
content: Thank you, Benta. That was the info I needed.
LM2679 short protection? - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: November 23, 2013, 05:24:37 pm
content: Does anyone know if the LM2679 has protection against shorts in the output? I have managed to destroy two of those before I realised what was happening and I believe it is because I shorted the output inadvertently by using an ammeter that requires isolated power supply (only the supply I used was not).

author: Bored@Work
author_rank: Super Contributor
timestamp: November 23, 2013, 05:40:53 pm
content: To lazy to read the datasheet?

author: Jon86
author_rank: Frequent Contributor
timestamp: November 23, 2013, 07:25:06 pm
content: "Resistor Programmable Peak Current Limit Over a Range of 3A to 7A."

author: akis
author_rank: Frequent Contributor
timestamp: November 23, 2013, 10:08:24 pm
content: Yes, and you'd think that with the current limit resistor the chip would be indestructible. Anyway, it may be because these ICs are from ebay - they have given me a ton of trouble. I have ordered a new bunch from Digikey and will test when they arrive.

author: Jon86
author_rank: Frequent Contributor
timestamp: November 23, 2013, 10:18:48 pm
content: What? I just answered the question, the chip DOES have output short protection.
LM27342 Circuit Help - Page 1
Forum section: electronics / projects

author: samuelkadolph
author_rank: Newbie
timestamp: February 21, 2022, 02:38:30 am
content: I've been working on a circuit to convert a supply voltage of 19V to 12V and 5V to power a hard drive using the TI LM27342 chip. But I've had a few issues.The first issue was not getting the correct voltage but I got some help and added some resistors to add a minimum load (7.3.3 in datahseet). Now the chip on the 12V would only last seconds before dying and heating up enough to melt the solder underneath. The 5V section lasted a lot longer and I was able to power a 2.5" HDD. It worked for over an hour before I power cycled and then the chip died.Am I missing something obvious? This chip seems really delicate. I didn't notice section 10.1.4 for PCB layout recommendations until after I needed to get help, seems unlikely it would cause my circuit to fry the chip though. And I know my inductor is a different value than TI's Webench Power Designer's reference schematic, that's because at some point they changed it and went from 3 input caps to 2 and reduced the inductor value.LM27342 DatasheetRef SchematicSchematicGerbersBoard

author: ledtester
author_rank: Super Contributor
timestamp: February 21, 2022, 03:00:47 am
content: I don't have any advice for troubleshooting your circuit but you can now get a TI eval board for only $6.28 from Newark (down from $53.90):https://www.newark.com/texas-instruments/lm27342myeval/dc-dc-buck-frequency-sync-evaluation/dp/04R9153Might help you figure stuff out.The eval kit's datasheet:https://www.ti.com/lit/ug/snva381b/snva381b.pdf

author: uer166
author_rank: Super Contributor
timestamp: February 21, 2022, 04:46:59 am
content: At 2MHz switching frequency and 10ns risetime you need really good layout with low inductance switching loop. Based on the pic it looks like your loops are extremely large/long, with thin traces. 1 inch of 50mil microstrip is ~20nH, which at 2A/10ns results in 4V overshoot (surprisingly low?). In any case that would put it right at the abs. max rating.How much current does the HDD draw from the converter? Does it fail at no load? Does it fail only with HDD attached? Did you attempt to measure/scope the switching node?In any case such a fast converter needs a much, much better layout to function.

author: samuelkadolph
author_rank: Newbie
timestamp: February 21, 2022, 09:54:14 pm
content: Thanks uer166, that does seem reasonable. Do you think I should make the FB loop might tigher or look for a lower frequency chip? I just went with one of the suggested designs from TI's website.One of my full sized drive draws 1.7A@12V during spin up then between 0.1-07A after that. And a max of 0.7A@5V. The chip wouldn't work at all without a load and didn't produce a voltage on the SW pins.I've been playing with TI's Power Designer again and this new chipLMR51420came up. Seems like a better idea but harder to get right now. I've also been looking for other switching chips and stock is zero for most.
LM2937 replacment - Page 1
Forum section: electronics / projects

author: mtechmatt
author_rank: Regular Contributor
timestamp: October 07, 2013, 01:29:26 pm
content: Hi Chaps...Made a boo boo on a prototype PCB. I designed it with the SOT-223 package with the layout:TOP TABGND IN OUTWhen in fact according to datasheet (http://www.ti.com/lit/ds/symlink/lm2937.pdf) it should of been:TOP TABIN GND OUTIs there any 500mA 5v LDO regs (12v input approx) that will fit my layout (I think it is a protues balls up as it was a library part!) or is it a new PCB? Any help mucho appreciated!!!!CheersMatt

author: Paul Price
author_rank: Super Contributor
timestamp: October 07, 2013, 10:01:57 pm
content: Just hard wire to get the correct pinout, it is just juxtaposition of two pins, so hand-solder it in with #32 silver-plated wire-wrap wire. Even the Chinese would do this on a 10000 piece production run until the PCB's were exhausted.

author: mtechmatt
author_rank: Regular Contributor
timestamp: October 09, 2013, 07:56:48 am
content: Paul,Thanks, thats what Ive doneThank the Chinese hehe
LM297 Stepper Motor Driver Clock Oscillator - Page 1
Forum section: electronics / projects

author: KRISTOFFER
author_rank: Contributor
timestamp: September 07, 2025, 08:17:55 pm
content: I got tired of circuits with 555 timers etc to provide the clock pulses for the L297 over the years and decided to have a look at the oscillator on pins 16 and 1 of the chip.There is not much about it on the data sheets but if you are not using it for it's normal function you can use it as a low frequency clock generator.Replace the 22k resistor on the data sheet application with a 3.3k resistor in series with a 50k pot. Replace the 3.3 nF capacitor with about 1uF.This will give you something in the range of 30 to 300 hz at sync pin 1 which can be directrly connected to clock pin 18.Although the duty cycle is not too good on a scope, it is adequate for a clock signal to control the speed of the motor.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: September 08, 2025, 01:53:27 pm
content: Thank you. These two Ics are used together in the Arduino Stepper motor shield, right?

author: MariuszD
author_rank: Regular Contributor
timestamp: September 08, 2025, 04:21:47 pm
content: Quote from: KRISTOFFER on September 07, 2025, 08:17:55 pmSense1 Sense2 is connected, so you're still using the chopper, that needs this generator.The chopper generator should operate at a much higher frequency than the step frequency.Chopper waveform in the attachment

author: KRISTOFFER
author_rank: Contributor
timestamp: September 27, 2025, 05:11:39 pm
content: The second diagram is from the data sheet. The first diagram is how to modify it to act as a clock oscillator. Take the output from the sync pin.

author: MariuszD
author_rank: Regular Contributor
timestamp: September 28, 2025, 10:04:24 pm
content: You'll have a free generator, but the motor current regulator won't work. Is it worth it?
LM309 - OK to apply voltage on output side only? - Page 1
Forum section: electronics / projects

author: ebastler
author_rank: Super Contributor
timestamp: March 27, 2016, 07:53:55 am
content: I got hold of an old Atari PONG board (from the original 1973 arcade game). After fixing the board, I want to install it in a flat "picture frame" cabinet, complete with a small flatscreen and paddle controls. The PCB has rectifier, big cap and an LM309 regulator on board to generate the 5V supply from an unregulated AC supply.To avoid the heat loss, and risk of malfunction, of the old LM309, I want to power the board with an external regulated 5V supply instead. But I want to leave the LM309 installed, to keep the board original. Will the LM309 tolerate that, or will it be damaged when it sees 5V on its output side while the input is open? Can't find any information on that strange use case, can't figure it out from the published internal curcuit, and don't have another LM309 around to try. Thanks for any hints!

author: Seekonk
author_rank: Super Contributor
timestamp: March 27, 2016, 08:12:36 am
content: If you tie the input and output together it will be fine.

author: ebastler
author_rank: Super Contributor
timestamp: March 27, 2016, 09:40:19 am
content: Thank you!Ideally I would want to tie the input and output together externally, on the board edge connector, to avoid any change to the board itself. But then the LM309 input would be one diode drop below its 5V output -- that won't do, right? A wire soldered directly between the LM309 input and output is a mod that is easy to revert, of course.
Lm317 as constant current source <10ma, what wrong happens - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: December 21, 2022, 05:53:42 am
content: The LM317 is given in DS >10ma for voltage regulation. If used as current source <10ma with TO92 version, what can go wrong?I tried out with 12v 7ma it worked perfectly with output ground to 8v.

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: December 21, 2022, 06:27:05 am
content: The LM317L from ST datasheet gives the following minimum operating current graph as voltage regulator, but what happens in current source?

author: timenutgoblin
author_rank: Regular Contributor
timestamp: December 21, 2022, 09:49:56 am
content: According to the Texas Instruments datasheet, the minimum load current is:>=3.5mA and =<5mA for VIN- VOUT=< 40V.Otherwise, it's:>=1.5mA and =<2.5mA for VIN- VOUTis >= 3V and =<15V.The minimum load current is required to maintain regulation. The values probably vary from device to device.7mA is more than the minimum load current requirement.See attachment below.

author: magic
author_rank: Super Contributor
timestamp: December 21, 2022, 09:59:35 am
content: Quote from: timenutgoblin on December 21, 2022, 09:49:56 amThis.If you try to "force" the chip to conduct less current, you may find that 1.24V across ADJ-OUT is not enough to stop it from conducting. Maybe 1.5V will be enough to throttle it down to 1.25mA and 2V for 1mA, maybe 20V will make it 0.75mA, maybe even 40V won't be enough for 0.5mA. (Numbers are made up.)What you will find is that it basically no longer works the way you want. You can just try it, I guess.

author: timenutgoblin
author_rank: Regular Contributor
timestamp: December 21, 2022, 11:19:26 am
content: Quote from: Kokoriantz on December 21, 2022, 05:53:42 amThe LM317L (TO-92) is the low-power variant of the LM317 (TO-220).For the LM317, the Texas Instruments datasheet gives the minimum load current:>=3.5mA and =<10mA for VIN- VOUT= 40V.See attachment for LM317 below. Also a functional block diagram.

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: December 22, 2022, 12:19:25 am
content: Thanks for the explanations. The two terminal current source needs a minimum current to establish the constant 1.2v. Then, if the current is less, it will not remain constant. I always read, never use LM317 less than 10ma as current source, when the 317L can be used instead of LM334, which needs some components to be temperature independent and it is much cheaper.
LM317 based power supply with current limiting - Page 1
Forum section: electronics / projects

author: mlemos
author_rank: Newbie
timestamp: February 23, 2014, 02:23:39 am
content: I'm trying to build my own Bench Power Supply but I'm having a hard time to find a good design (circuit/project) for it.I watched the first videos from our host on building a lab power supply, but I want something simpler without micro-controllers. And I pretend to use two LM317 in the project.And one special question, when David says about power supplies with "multi turn pots" are they usually used on the "voltage adjustment" or "current adjustment"? Or both?Here are my requirements:Input: main using a 18+18V 2A transformerOutput: 0-18VCurrent: 0-1.5ACurrent Limiting controlled by a potentiometerVoltage output controlled by a potentiometerAnd I'd love it to be based on the LM317I know there are some designs with two LM317, one limiting current and the other controlling the voltage output, but I couldn't find any good reference for those circuits.All help is welcome!

author: tautech
author_rank: Super Contributor
timestamp: February 23, 2014, 02:37:29 am
content: Also consider the LM338.
LM317 current limit indicator - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: April 09, 2013, 08:20:21 am
content: I thought someone might just have an elegant solution to this little problem.I just want to quickly put together a multi-channel float charger for the several motorbikes and batteries I have in the shed. Nothing over complicated, just float charge the batteries at an appropriate voltage (13.5V) with a reasonable current limit (~100-150mA.)Easiest option I see is the serial connection of two good old LM317s per channel connected off a plug pack, job done.Whilst I have no need for current monitoring (I'll just use a DMM if I want to look at a battery.) It would however be useful to know if a channel is in current limit. This can indicate somethings askew or the battery needs properly charging.So that brings me to the question. I can't come up with a good way of just putting a couple of LEDs in to indicate it's in CC or CV without throwing op-amps at the circuit and putting in a second monitoring circuit for the voltage across the current sense resistor, which kind of defeats the ease of just using LM317's in the first place. I figure LM317's have been around as long as the hills, surely someones done this before in an elegant way?Cheers

author: Harvs
author_rank: Super Contributor
timestamp: April 09, 2013, 09:01:05 am
content: Never mind, I stumbled across this thread:https://www.eevblog.com/forum/beginners/adding-a-'current-limit-reached'-led-to-a-317-current-source/Works like a charm.
LM317 like for like with lower quiesent current - Page 1
Forum section: electronics / projects

author: titium
author_rank: Newbie
timestamp: September 29, 2014, 11:49:18 pm
content: I have a project which has a max power spec and i overlooked the fact the 317 can draw upto 10mA bias currentthis pushes me just over the power spec.Does anyone know of a like for like replacement for the lm317 (in SOT223 package) with lower operating current?Output is 12V.

author: Phoenix
author_rank: Frequent Contributor
timestamp: September 30, 2014, 01:14:52 am
content: What's the input voltage and output current requirement?Seeing as linear regulators are inherently incredibly inefficient could you use some sort of small switching/buck converter?

author: titium
author_rank: Newbie
timestamp: September 30, 2014, 02:58:00 am
content: Input voltage is 18v output is 12v. Using it for analogue signal conditioning.There is also tight specifications on the supply noise hence the requirement for a linear reg.Output current is approx 20mA

author: SArepairman
author_rank: Frequent Contributor
timestamp: September 30, 2014, 03:06:49 am
content: You can do a switcher followed by a LDO, but I don't know how good that will be. I might measure this when my switching module 317 replacements come in.The LT3080 uses a very high value resistor for voltage set (1.2 Meg @ 12V), quiescent current of less then 1mA

author: Phoenix
author_rank: Frequent Contributor
timestamp: September 30, 2014, 11:33:16 am
content: Quite a few manufacturers (TI, Analog) offer online power regulator designers. Put in your specs and see what they come up with.

author: macboy
author_rank: Super Contributor
timestamp: September 30, 2014, 12:38:38 pm
content: For only 20 mA and just 6 V of drop, you can use a TO-92 package, like 78L12. The "L" version uses less quiescent current than the normal version in TO-220 package, and it use usually less noisy too (check specs on your part, there are dozens of variations out there). Why use an adjustable regulator when a fixed one will do? You usually use more quiescent current in the adjust resistor network than when using a fixed regulator. The 78L12 uses about 2 mA q.c., but you can probably find other more modern fixed regulators with less.

author: mij59
author_rank: Frequent Contributor
timestamp: September 30, 2014, 01:03:54 pm
content: You could use the Microchip MCP1804Thttp://www.digikey.nl/product-detail/en/MCP1804T-C002I%2FMT/MCP1804T-C002I%2FMTCT-ND/2170960,or Holtek HT7150 with two resistorshttp://nl.farnell.com/holtek/ht7150-1-sot89trlf/v-reg-ldo-5-0v-0-03a-smd-sot893/dp/1420875.
LM317 based   simply low current (125mA) battery (24V) charger  - Page 1
Forum section: electronics / projects

author: szan
author_rank: Regular Contributor
timestamp: September 29, 2021, 08:55:03 am
content: Hello,I'd like to make simply low current battery (24V) charger based on LM317 datasheet from TI:when we assume for 24V output voltage:R2=2000R1=110and ~125mA output current limit:RS= 10then we have according to LM317 datasheet:Vout=23.977 ~24VIout= 0.125AmaxI know that, I should have input voltage Vi>Vout+4.25V - It will be around 30V.Is it possible that LM317 will in this case limit output current to <=125mA by using this RS=10 Ohm resistor or It could be better add additional NPN transtror like in circuit attached below?Thanks in advance for any sugestions.RegardsSzan.

author: iMo
author_rank: Super Contributor
timestamp: September 29, 2021, 09:07:46 am
content: With RS=10ohm the charging current will not be higher than 130mA (first picture 9.3.6).Mind the battery will be discharged through the resistors when the charger will be switched off the 30V input..

author: szan
author_rank: Regular Contributor
timestamp: September 29, 2021, 10:24:37 am
content: Quote from: imo on September 29, 2021, 09:07:46 amIt looks like this discharge current will be around ~11mA, so something like low current 50% powered LED 5mm which is fine, since battery capacity is around: 18000 mAh.Idischarge= 24.0/(2000+110 )Of course LM317 will be additionaly protected by 1N007 diode between Vout - RS -> Vin capacitor, as well as another 1N007 diode between input voltage source and LM317 input capacitor - in the case when input voltage drops below battery voltage - solar panel will be used to charge this battery.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 29, 2021, 01:17:02 pm
content: Quote from: szan on September 29, 2021, 10:24:37 amIf the Vmp of the solar panel is close enough to the charging voltage, just have an overvoltage cutout.

author: szan
author_rank: Regular Contributor
timestamp: September 29, 2021, 08:59:50 pm
content: Quote from: NiHaoMike on September 29, 2021, 01:17:02 pmNope, I need current & voltage limit to do not overvoltage each battery cell and try to keep it below 4.0V.I think it will be goo didea add addtional 1N4007 diode to battery input,while voltage drop 0.7V at 24V battery during charging its 6 cells in seriesgives ~3.9V on each battery cell which extends its lifespan by not charging to 4.2V but trying keep it at 3.9V level.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 30, 2021, 12:49:58 am
content: Quote from: szan on September 29, 2021, 08:59:50 pmThen just adjust the cutout point to right where you want it.
lm317t power supply, need feedback - Page 1
Forum section: electronics / projects

author: little_carlos
author_rank: Regular Contributor
timestamp: April 15, 2014, 10:47:47 pm
content: hi, im about to do this design for a power supply that im about to do, the lm317t that i bought was faulty so il get another oneI want it to power my little electronics projects, but im making it 30v- 3 amps so if someday i need it, i could use itive already bought the components so please tell me how accurate will it work, i understand that the lm317t is for controlling the 2n3055, im using this power transistor so the lm317 dont melt down and burn up all the chasis

author: mariush
author_rank: Super Contributor
timestamp: April 15, 2014, 10:58:10 pm
content: You already asked here, stick to one thread:https://www.eevblog.com/forum/beginners/lm317t-power-supply-question/msg425831/#msg425831Did you even check the datasheets I linked to, to see the example circuits shown inside the datasheets? Did you read the advices other people told you, or you're just stuck on that picture?

author: digsys
author_rank: Unknown
timestamp: April 15, 2014, 10:59:19 pm
content: I'd seriously consider it's larger brother - the LM338K, which is the 5A version !! The BIG problem with pass transistors is thatyou lose thermal shutdown in case of a short !! (It's built into the Regulator only). That circuit does work though with limitations

author: little_carlos
author_rank: Regular Contributor
timestamp: April 15, 2014, 11:07:31 pm
content: i dont find the lm338 anywhere

author: mariush
author_rank: Super Contributor
timestamp: April 15, 2014, 11:17:03 pm
content: You can also look for LD1084 , LM1084 , or anything with 1084 in the name .. these can do 5A with good heatsink. LD1085, LM1085 , *1085 can do 3A.No matter what you pick - and I already explained it to you - linear regulators dissipate the difference between input voltage and output voltage as heat ... number of watts wasted is (Vin- Vout) x Current ...Stop trying to use use a simple transformer that will give you 30v dc at the input and use a transformer with two secondary windings - use just one winding when you need lower voltages, connect both windings when you want higher voltage.For example get a 24v AC transformer with center tap or two separate secondary windings .. when you connect just one winding to bridge rectifier, you get 15v DC, when you connect both windings in series, you get 30v DC. So when you want to have 1.25v - 12v you use just the first winding, when you want more you connect both windings in series.
LM324N OA Frequency Generator Unused Pin Termination? - Page 1
Forum section: electronics / projects

author: t1d
author_rank: Super Contributor
timestamp: February 21, 2017, 07:09:49 am
content: I am using a jellybean LM324N Quad Op Amp to build a frequency generator. The manufacturer is unknown. I need to know how to properly terminate the unused op amp pins. I read the Texas Instruments brand data sheet, but did not see it mentioned... Ground, float, other? I think I remember seeing something about float would be best, but can't remember, for sure. Suggestions?Thank you for your help.

author: SingedFingers
author_rank: Frequent Contributor
timestamp: February 21, 2017, 07:18:56 am
content: Maxim have a good app note on this:https://www.maximintegrated.com/en/app-notes/index.mvp/id/1957

author: t1d
author_rank: Super Contributor
timestamp: February 21, 2017, 07:24:24 am
content: Thanks Singed! Excellent!

author: not1xor1
author_rank: Frequent Contributor
timestamp: February 21, 2017, 09:21:15 am
content: Quote from: t1d on February 21, 2017, 07:09:49 amunused LM358/324 amps should be configured as voltage follower with the non-inverting input connected to the negative supply branch (at least that produced the best result when I checked with my ST ICs)somebody suggests anyway they consume less when the input is connected to half Vcc-Veesince you do not know the manufacturer you can just check on a breadboard:- connect a multimeter in mA range in series to Vcc- configure all amps as voltage followers- compare current amount with all inputs to Vee vs. inputs at half Vcc-Vee and see yourself what is best

author: Avacee
author_rank: Unknown
timestamp: February 21, 2017, 09:36:46 am
content: For suggestion overload TI have a video showing what to do for single and split supply.

author: SingedFingers
author_rank: Frequent Contributor
timestamp: February 21, 2017, 09:40:08 am
content: Also avoidance is a possibility. ST TS321 is a single LM324/358 in a SOT23 package. Problem solved - no left over op amps

author: CJay
author_rank: Super Contributor
timestamp: February 21, 2017, 10:08:17 am
content: Handy TI video, subscribed. It's nice to know I've been 'doing it right' even if only because it 'made sense' to me.That and Dave's tutorials on op-amps are well worth a watch.
LM334 Constant Current Source Question - Page 1
Forum section: electronics / projects

author: MotoDan
author_rank: Contributor
timestamp: March 16, 2023, 07:23:51 pm
content: Hello All,I have a circuit that has been in production for years which uses the LM334 as a constant current source, My ATE test fixture applies 3V vi R3 which is varried from 500k to 1M, The ATE measures Vout accordingly. My LTSpice model matches the actual performance, however we just discovered that the LM334 behaves the same (and passes the ATE test) when it is inserted backwards.The TO-92 package has the following pinout:Pin 1 - V+Pin 2 - ResPin 3 - V-Flipping the part keeps pin 2 as Res, but reverses V+ and V-.I have tried a couple different Spice models, but both only work when the device is installed correctly.I would like to be able to catch a reversed part in my ATE, but don't see a way to do it since both scenarios yield the same output on Vout.I have only tried National/TI parts.Any ideas?

author: magic
author_rank: Super Contributor
timestamp: March 16, 2023, 07:55:43 pm
content: SPICE models of ICs tend to be simplified or outright abstract, so they may not reflect true behavior under abnormal conditions.This chip has zero reason to work backwards in general, but it can accidentally produce correct outcome under certain particularly (un)lucky conditions. In such case, it should be enough to change the test procedure and likely the output will become obviously bogus. Experiment with real chips, not SPICE models.That being said, I'm not sure how your circuit is supposed to operate normally. There is expected ~64mV across R1 and then R1 current has to flow through R4, dropping 4.7V there, but your supply is merely 3V.

author: Kim Christensen
author_rank: Super Contributor
timestamp: March 16, 2023, 08:34:06 pm
content: Quote from: MotoDan on March 16, 2023, 07:23:51 pmWhat range of Vout constitutes a pass according to your ATE?Do you have to test it with that exact setup? A proper test current should detect a device inserted in reverse.
LM337 Questions - Page 1
Forum section: electronics / projects

author: tango17
author_rank: Regular Contributor
timestamp: February 26, 2016, 06:21:51 pm
content: I'm building a 30v 5A PS using rail to rail op amps, and need to be able to pull a control diode below ground. A charge pump will provide unregulated input to the negative rail, which I plan to be at -1.25v provided by an LM337.Q1. Can I just connect the adjust lead directly to ground to set the -1.25 I want or is there some reason I need a resistor between adjust and ground? IOW, can I treat the 337 as a fixed -1.25 regulator?Q2. Do I need to guarantee min output current by connecting a resistor across the output to pull all that cuurrent, or can I rely on the other components to pull some of that current? I'll be powering a dual opamp MC33072 and another single op amp TLE2141, both from near 40v to -1.25. The 337 specs seem to say 10mA max may be needed for regulation. The 33072 says 2.8mA and the 2141 says 3.4mA. Those are worst case idle currents with no loads. Can I just pull another 4mA with a 330R resistor to guarantee regulation?Thanks

author: tango17
author_rank: Regular Contributor
timestamp: February 26, 2016, 06:32:55 pm
content: Actually, I just realized the 33072 numbers are per amplifier, and I forgot its powered from only 20v, so it looks like the specs say 1.6mA per amp is minimum, which times 2 is 3.2, not far off the 2.8 used above.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: February 26, 2016, 07:03:49 pm
content: A1. It does not matter about the adj pin. Connect it straight to ground if you want. I believe it is internally connected to an op-amp so it does not matter.A2. It does no harm to put the 330R resistor on. about 2-3mA will guarantee it being stable.

author: tango17
author_rank: Regular Contributor
timestamp: February 26, 2016, 07:17:21 pm
content: Thanks. The charge pump can't produce a lot of current, so I didn't want to draw any more than needed. My simulation says it draws 20mA even without the 330 ohm, and it's keeping the 337 happy up to 40mA, so I've got some room to work with, I just didn't want to waste any of the limited output current.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: February 26, 2016, 08:36:07 pm
content: I forgot about the charge pump. Send me what you are using for the charge pump and ill test if it is stable with the lm337.
LM338 Power supply update - Page 1
Forum section: electronics / projects

author: rpetitho
author_rank: Contributor
timestamp: November 05, 2019, 09:58:31 pm
content: So I built up my power supply from a previous post. (https://www.eevblog.com/forum/projects/my-first-power-supply-212774/msg2719512/#msg2719512) I had to make a few adjustments for performance and created a new schematic, pdf attached. Here are some performance curves, let me know your thoughts.Transient Load Response: Set at about 9.7v, switch a ~10ohm resistor and drive about 1 amp. Drops by 600mv then recovers in about 3us. I think its good.Overcurrent Cut-out. Set at about 9.7v and current limit at about 0.25 amps, instant connect ~10ohm load. Voltage drops most of the way in about 40us, and settles after about 150us. Decent?Finally, a bit of a strange one here. A similar test to the first except this is the response when disconnecting a 10ohm load (about 1 amp). The response starts off as an inverse picture to the first curve, but then goes into a long saw tooth shape. Not sure why this is happening. I found this on the internet reference a LM317 doing somthing similar. (https://e2e.ti.com/support/power-management/f/196/t/372417) I think the performance is still decent, but curios why it is happening.-Bob

author: ezeisel
author_rank: Newbie
timestamp: November 06, 2019, 04:24:46 am
content: The transconductance and so essentially the speed of the NPN series pass transistor in the LM338 is proportional to its output current, hence the asymmetry: it can charge the output node up fast, but the node is only discharged by the 5 mA min load + quiescent current and output voltage setting divider current... so pulldown is slow.That doesn't really explain why it's underdamped. But I think that is also related to the asymmetry: the output stage is very slow when the current is low, so the output pole is closer to the internal dominant pole, reducing the phase margin when voltage is dropping, leading to undershoot that is then corrected with another overshoot etc.