hybridfree/eevblog-posts huggingface dataset:
LM3409N PFET buck controller refusing to operate? - Page 1
Forum section: electronics / projects

author: rs20
author_rank: Super Contributor
timestamp: January 11, 2016, 09:23:20 am
content: I've built up a veroboard circuit centered around a DIP LM3409N (datasheet), and it's just refusing to switch -- the PGATE pin seems to be locked to the VIN pin (which, since it's hooked up to a PFET, means "off"). I've checked with the oscilloscope, and there's no AC life on any of the pins, it's pure DC. I've annotated a diagram with the DC voltages below:Coff is connected to Vout (which lazily ramps up to about 6V after 20 seconds or so, there must be some leakage somewhere) via a 190 kiloohm resistor, and is connected to ground via a 470pF cap. I've checked for shorts from PGATE to any other node, but can't seem to see anything. There's a 10uF MLCC SMD cap between VCC and VIN. In any case, I'm surprised to not see any life on either the COFF or PGATE pins; the UVLO, IADJ and EN pins all appear to be correct. It's fairly warm here today, but not quite warm enough for the thermal cutout to activate methinks.Does anyone have any ideas what the problem might be, before I fall back on the assumption that I statically zapped my IC and I need to replace it?EDIT: Fixed broken image link.

author: MagicSmoker
author_rank: Super Contributor
timestamp: January 11, 2016, 05:35:48 pm
content: You almost certainly need to connect the die attach paddle on the underside of the IC to ground for it to work.EDIT - correction, I see you are using the PDIP version so, nevermind.

author: georges80
author_rank: Frequent Contributor
timestamp: January 11, 2016, 05:50:44 pm
content: Quote from: rs20 on January 11, 2016, 09:23:20 amVeroboard? Eek! Pictures and schematic would help...Switchers (esp high speed, high current) and veroboard, protoboards etc rarely will have a positive outcome.cheers,george.
LM3478 Boost Converter - Page 1
Forum section: electronics / projects

author: Signal Simon
author_rank: Contributor
timestamp: March 04, 2015, 12:03:43 am
content: I've made a couple of successful LM3478-based boost converters for obtaining 5V and 12V rails in a portable device powered by 3 AA Cells.The 12V is enabled/shutdown by the micro as required, which saves about 7mA - "You could fly to the moon on that" as Dave would say.Component selection primarily based on Webench, but substituting easily hand-worked component variants, eg 0805 passives and SO-8 IC and FET.Next project is a pocket power supply that will deliver 24V at 300mA or 50V at 150mA (switchable) from 4 AA Cells.The ideal scenario is that I only want to switch in a parallel resistor to the feedback network to select output voltage.However, the suggested compensation network values have ranges which do not overlap.One solution I have found (in theory!!), is to run the converter at 100kHz in the 50V mode and at 120kHz in the 24V mode, by switching in an extra 47K on the FA pin, which then means I can just switch in an extra 2K2 on the Comp pin, as the suggested values for Ccomp 1 and Ccomp2 then remain the same.Do I need to go to the trouble of an extra 2 mosfets and resistors, or can I just run at 100kHz and go with the larger compensation components for lower crossover frequency, as that's what the app note seems to imply?I've mashed my head with the old National Semiconductor Application Note AN-1286 and right half plane zeros!Simon.
LM3485 high current step-down regulator - Page 1
Forum section: electronics / projects

author: mrmp17
author_rank: Contributor
timestamp: November 03, 2013, 07:27:02 pm
content: Hi everyone!I'm working on high current switching regulator and I have a few problems to solve.Regulator will be powered from rectified 450W, 24V transformer. I need around 300W on output at around 16V (voltage must be adjustable with a pot). I'm now in breadboard testing stage and things don't work quite wellMy controller is LM3485 (Hysteretic PFET Buck Controller) datasheet:http://www.ti.com/lit/ds/symlink/lm3485.pdfPFET - IRF5305 datasheet:http://www.redrok.com/MOSFET_IRF5305_-55V_-31A_6mO_Vth-4.0_TO-220.pdfDiode - BYV32-200 datasheet:http://www.onsemi.com/pub_link/Collateral/BYV32-200-D.PDFInductor - 68uH, 3A (just for testing)Low ESR in/out capsI assembled everything on breadboard (see Typical Application Circuit in LM3485 datasheet) and on the first look it was working just fine (12V source, 5V output), but when load was connected (around 2A) voltage dropped for almost a volt !Also mosfet got really hot, even with heatsink. I measured everything and got very poor efficiency, I don't remember exactly, it was aroud 60%.I also have problems with current limit. I haven't had connected the Isense and ADJ pins on anything. I don't know how to calculate the ADJ resistors. Can anyone teach me how to calculate the resistors? When I connected the Isense wire to drain of mosfet and LM3485 went in smoke - didn't have ADJ resistors connected yet (my fault, I had the circuit connected to power). So I have to solder a new one on adapter to get testing again.So, anyone have an idea why I have so poor efficiency?
[need help] Make LM3488 regulate output from 0V - Page 1
Forum section: electronics / projects

author: Unixon
author_rank: Frequent Contributor
timestamp: July 20, 2020, 11:23:54 pm
content: Hi,I have a piece of hardware with LM3488 in non-isolated forward configuration (common ground) with 1:10 step-up transformer (ATB3225) powered from 5V input. LM3488 is used as a digitally controlled voltage source in [0-150V] range to drive a PZT actuator. The problem is the lowest stable output voltage this solution is capable of producing is about 12V (8% full scale, heavily depends on output loading) at f_sw=100kHz and I need to go down to 5V or less. At f_sw=400kHz the lowest stable Vout is ~25V. Cout~1-10uF, Rfb~0.5MOhm.I'm probably hitting the minimum "on time" T_on=325ns limit, or something like that and I'm already at the minimum switching frequency. Reaching this limit results in low frequency like 50Hz triangle wave oscillations at full Vout amplitude instead of stable constant Vout.Loading the output with additional capacitance or introducing an LC-filter after secondary transformer winding breaks regulation much faster than lowers stable output voltage. So, the only other attempts to calm LM3488 down I can think of is limiting the primary side current with a higher value current sense resistor and/or lowering the switching frequency beyond the spec limit to reach a lower minimal duty cycle.Will LM3488 tolerate lower switching frequencies like, say, 30kHz?

author: Unixon
author_rank: Frequent Contributor
timestamp: July 21, 2020, 08:58:36 am
content: Update:This topic describes similar issue with different topology:https://e2e.ti.com/support/power-management/f/196/t/333595?Reg-LM3488-Boost-convertor-output-oscillation-without-minimum-loadHere's the piece of LM3488 circuit: (see attachment)C33,C34 are replaced with 3x0.47uF caps.Regulation above minimum Vout threshold of ~12V is perfect, but below this level I also get low frequency full amplitude oscillations probably for just the same reasons.Is it possible to bring this minimum output voltage down?p.s. Most of this circuit previously belonged to DRV2700, but I had to drop that IC because of its naturally high ripple at certain Vout ranges.
lm361 datasheet error? - Page 1
Forum section: electronics / projects

author: diegoperez
author_rank: Contributor
timestamp: December 08, 2016, 10:30:30 am
content: I just wanted to double check because maybe I'm missing something; but, the footnote in the logic diagram in page 2, shouldn't it be "Output ishighwhen current is drawn from strobe pin"?Here is the link to the datasheethttp://www.ti.com/lit/ds/symlink/lm161.pdfthanks

author: diegoperez
author_rank: Contributor
timestamp: December 08, 2016, 10:47:12 am
content: Quote from: blueskull on December 08, 2016, 10:39:07 amOh, ok, thanks for answering. just one more question, what kind of transistor is q14 and is there any documentation that you would recommend where I can read about it, so that the next time I could understand better the schematic?
Lm386 Amp Circuit Housing And Effects - Page 1
Forum section: electronics / projects

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: February 04, 2013, 08:27:51 pm
content: Hey guys after i resolved my problem with the Lm386 circuit i have to put it somewhere....I have no idea where.I am thinking of making a wooden stracture maybe to house it in but i do not know what should i build.1st)I need good ventilation i was thinking about adding a fan that cools the chip directly from above and two other fans on the sides to send the hot air out of the caseQ1 what diameter fans should i useQ2 Shall i power them from an external power supply ?? (my Lm386 circuit works with 9 volts and i will need 12 volts for max speed and i think that i should add a Lm317 circuit for controlling the fan speed (1.25-16 volts which fans wont be destroyed)Q3 where should i place the fans on the box?Q4 if i add an Lm317 circuit board and power the fans from the original power will it effect the audio amplifier wattage or sound ?As for the other parts.Q1 I want to put an internal speaker to the system so that i can choose if it the output is the speaker of the orignal output (3.5mm or 6.35mm) how can i do that (will it take only a regular switch ?)Q2 I think that i will need to elevate the board from the base of the wooden stracture about 1-2cm shall i ?Ideas1) I am thinking of putting an extra Led for power with a resistor so it wont get burned.2) I will add the pot on the top of the box so i can adjust the volume3) i would like to add a female header on the circuit board so that i can change the capacitor for extra or less gain and also be able to add a bass boost with a 10k resistor and a 0.33uf capacitor.4) i would like to add more switches on the top so that i can add distortion effects on the circuit.AUDIO EFFECTS.I have no idea how to use caps for audio effects but i would like you to tell me what to do.THANK YOU.
LM3914 Li-ion voltage meter  - Page 1
Forum section: electronics / projects

author: anishkgt
author_rank: Frequent Contributor
timestamp: April 19, 2019, 05:06:25 pm
content: Hello All,Can somebody please advise the correct way to wire these up to indicate the voltage of each cell. The voltage is 7 cells in series at 4.2v and the lower voltage is 3 and highest is 4.2. I saw Dave's video on how he uses the IC with 8.4v but i do not know how it would be in a 7 cell configuration.Would appreciate if any would helpWww.Georgehobby.wordpress.comEquipments: DSO104z, Hakko FX888D, Brymen BM869sSent from my iPhone using Tapatalk
LM3916 bargraph driver board - Page 1
Forum section: electronics / projects

author: reagle
author_rank: Unknown
timestamp: July 05, 2013, 11:19:10 pm
content: Hi all, here is my attempt at making an LM391x breakout board that's usable in many different configurations.Oddly enough I did not even know of these chip's existence until I saw Dave's battery monitoring video.We, the youngsters..Schematic is inhttp://kuzyatech.com/wp-content/uploads/2013/07/DipTrace-Schematic-201305_LM3916_BargraphPreview.pdfI've built the first prototype with sockets for the bargraph array and the driver for testing purposes. Eventually they'll just be soldered in.Feeding it a ramp signal from my generator, I get a nice bouncing graph so it appears functional at the basic level.A few pictures are attached.Comments/suggestions/questions are welcome!

author: mariush
author_rank: Super Contributor
timestamp: July 06, 2013, 02:01:57 am
content: Why the mess with the DIP socket and having to take out the LM3916 to solder the part?I'd get rid of that third hole, two holes should be enough to support such a light pcb. move led segments toward the top.Then I'd take the three resistors and turn them 90 degrees and on the other side of the lm3916, same with that capacitor (i'd use 2 x 10uF if needed just to get small diameter to put in flat like a resistor)turn r3 and the other 90 degrees , basically get all resistors nicely aligned there ...put r5 there on board and maybe add a jumper shorting it when not needed (or disconnecting the trace etc) ...All power and input-output pins should be towards the bottom where the screw holes are so that the weight of the cables won't bend it...
LM394N substitude? - Page 1
Forum section: electronics / projects

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 29, 2022, 07:58:26 am
content: A circuit is defect and of course protected in a insane hard resin, I have managed to dig out the defect part, a LM394N, but this part is almost unoptanium. Do you know of a supermached pair that is nearly the same in specifications?Unfortunately, do I not have any idea of how precise I have to be to make sure it works greatly another 15-20 years.The LM394N is a PNP - NPN matched pair in one chip.

author: magic
author_rank: Super Contributor
timestamp: March 29, 2022, 08:08:48 am
content: LM394N is a matched 2×NPN pair and N stands for DIP8 package.

author: not1xor1
author_rank: Frequent Contributor
timestamp: March 29, 2022, 08:15:19 am
content: Quote from: FriedMule on March 29, 2022, 07:58:26 amWRONG: LM394N is just an NPN matched pair in a DIP package.

author: wraper
author_rank: Unknown
timestamp: March 29, 2022, 08:22:16 am
content: You could use SSM2212 on adapter PCB or try your luck on Aliexpress and hope to get a genuine part salvaged from e-waste.

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 29, 2022, 10:13:01 am
content: Hmm... I did search the wrong place about the chip because an "expert" had written about them being NPN-PNP pair, thanks for correcting that.The SSM2212 looks great, I have not compared them yet, but I imagine they are about the same?

author: JPortici
author_rank: Super Contributor
timestamp: March 29, 2022, 11:15:48 am
content: AS394 from many sources

author: strawberry
author_rank: Super Contributor
timestamp: March 30, 2022, 09:28:26 am
content: AS394 modern replacement in productionoriginal storehttps://www.ericasynths.lv/shop/ics/

author: JPortici
author_rank: Super Contributor
timestamp: March 30, 2022, 11:49:16 am
content: Quote from: strawberry on March 30, 2022, 09:28:26 amAFAIK the manufacturer ishttps://www.alfarzpp.lv/eng/sc/semiconductor.phpand ericasynths was just their first reseller
LM399: Buffer before voltage divider? - Page 1
Forum section: electronics / projects

author: Penguin36
author_rank: Contributor
timestamp: February 27, 2018, 12:45:20 pm
content: Hi,I‘m working on a project that needs an accurate voltage reference.Using a LM399 in bootstrap circuit I want to use the 6.95... V from the LM399 and divide that down to 5V and 2.5V (switchable voltage divider) and than buffer this output.I found, that Vz drops about 0,00010V when connecting the voltage divider (54k ohm in total) directly to the LM399. DMM is connected to LM399 output.So, is it better to add another buffer opamp between the output of the LM399 and the input of the voltage divider? I want to keep noise as low as possible too.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 27, 2018, 01:13:40 pm
content: The output impedance of the LM399 is rather low. So there is no problem to connect a constant load to it. The divider needs to be low TC anyway and thus is a constant load. One might have to do the switchable part of the divider in a way to keep the load constant - thus having the fixed divider to 5 and 2,5 V and only choose the output to a common buffer after the divider.

author: Penguin36
author_rank: Contributor
timestamp: February 27, 2018, 01:26:47 pm
content: Ok, when switching to 2.5V the load is about 22k ohms. At 5v its about 54k as I wrote before.The divider resistors are 0.01% 2ppm types btw.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 27, 2018, 02:04:35 pm
content: Switching between a 54 K and 22 K load is not such a good idea - the switch itself can already be a problem and in this case one would need a buffer or add a compensating load to bring the 54 K to 22 K too. The easier way is switching at the output of the divider.With the LM399 you don't have to worry that much about amplifier and resistor noise, as the LM399 is relatively noisy to start with.
LM4889 Audio Amp Issue - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: August 06, 2014, 09:31:59 pm
content: I decided to make a small audio amp and I'm having some issues.I used the LM386 in the past and it worked fine, but I decided to try the LM4889 since it's a 1W amp (as opposed to the 0.3W) and it's supposed to work without the huge electrolytic caps required by the LM386. Unfortunately, it does not seem to be working like I had hoped. I can get a tone from my function generator amplified through a pair of headphones, but nothing speech wise, nor through a small 8-Ohm speaker.The application information in the datasheet is so barebones and simple... It's hard to see where I went wrong. The Speaker is isolated and connected directly across the amplified output connector JP1. A verified working microphone is connected to X1.Does anyone have any ideas?LM4889 Datasheethttp://www.ti.com/lit/ds/snas157h/snas157h.pdf

author: Precipice
author_rank: Frequent Contributor
timestamp: August 06, 2014, 09:36:34 pm
content: The schematic looks fine - so I'd guess you've not built what you think you built.Photo?

author: Pack34
author_rank: Frequent Contributor
timestamp: August 06, 2014, 09:53:03 pm
content: I got ahead of myself and had some made. It's hard to say no when iTead is only $15...EDIT:// I started with one of these small microphones below until I attached a standard 3.5mm microphone to the board just in case I damaged the thing when I soldered it on.Microphone datasheet:http://www.cui.com/product/resource/cmc-5042pf-ac.pdf

author: mamalala
author_rank: Unknown
timestamp: August 06, 2014, 10:40:54 pm
content: Quote from: Pack34 on August 06, 2014, 09:53:03 pmThat is an electret microphone, you need to hook it up to the supply through a resistor. The negative side of the mic goes to gnd, the positive side splits into two: one through a resistor to the supply voltage, the other to the audio input of your circuit (that is, into the input of X1 in your schematic). You already have a capacitor in line there (C4) which is required, otherwise you get DC on the amp's input.Greetings,Chris

author: Pack34
author_rank: Frequent Contributor
timestamp: August 06, 2014, 10:52:30 pm
content: Quote from: mamalala on August 06, 2014, 10:40:54 pmAnd I think that did it. I slapped on a 2k2 pull-up on the microphone. It sounds good and loud through a set of headphones but not the 8 ohm speaker. I guess at this point it's playing with the feedback look to get the gain to where I want it.Thanks! I'll be sure to share the design files when I'm happy with the output.EDIT:// As per the datasheet, the gain is proportional to the feedback resistor divided by the resistor in series with the input. Scaling up the Rf to 200k seemed to do the trick for me. Also slapping a 22pF cap in parallel with it helped.
LM5019 Buck controller ....constant on time mode - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: September 18, 2018, 03:58:14 pm
content: The LM5019 is a Buck controller which is meant to operate in constant on time mode.The internal power FET is turned ON and stays on for the ON time as calculated by expression (3) of page 11 of the datasheet.[however, the ON time can be prematurely curtailed if....a).....the Vout divider voltage goes above 1.62Vb)....the inductor current goes above 240mA]The internal FET OFF time is terminated either...........a)...by the vout divider voltage falling back through the reference voltage of 1.225Vb).....By the OFF time as calculated by expression (4) of page 11Presumably, the OFF time given by expression (4) of page 11 never occurs unless the inductor current hits the 240mA threshold?If the inductor current hits the 240mA threshold, then i would expect the OFF time to wait as long as it takes for the vout divider voltage to fall back though the 1.225V reference voltage....is this what happens?LM5019 datasheethttp://www.ti.com/lit/ds/symlink/lm5019.pdf

author: Jebnor
author_rank: Regular Contributor
timestamp: September 18, 2018, 04:28:20 pm
content: No idea, but I will add that concept to my bag of tricks. An interesting spec sheet read
LM5035 PWM controller help - Page 1
Forum section: electronics / projects

author: Kedar264
author_rank: Regular Contributor
timestamp: December 04, 2018, 01:03:11 pm
content: HiI am using LM5035 , in my voltage regulator can anybody help me finding pin for output voltage controlLm 5035 datasheethttps://www.google.co.in/url?sa=t&source=web&rct=j&url=http://www.ti.com/lit/ds/symlink/lm5035.pdf&ved=2ahUKEwi2g5_znYbfAhWCfisKHft-DWsQFjAAegQIARAB&usg=AOvVaw0H5h77Ns1tq3fI-zkGWIoSAny help is precious thanks

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 04, 2018, 02:43:05 pm
content: Quote from: Kedar264 on December 04, 2018, 01:03:11 pmThe adjustment is made here. What is your circuit for the error amplifier?
LM5106 - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: October 23, 2013, 08:12:27 pm
content: To reduce the number of PWM outputs that I need, I was looking at the LM5106 and was wondering if anyone here had some experience with it. It's intended purpose is to be a FET driver with a programmable dead-time between the PWM pulses.My only concern is the effect of leaving the high side source and boot strap connections floating and if that would have an impact on the output signal on the high side output.LM5106 Datasheethttp://www.ti.com/lit/ds/snvs424c/snvs424c.pdfEDIT:// Just to clarify, I know how an H-Bridge works and why the boost rail exists. It looks like leaving the high-side source pin floating should give me the output that I need, I was just wondering if someone here had experience with the chip so I wouldn't have to have breakout boards made to test the chip on my bench.

author: free_electron
author_rank: Super Contributor
timestamp: October 23, 2013, 08:50:16 pm
content: It would help if you explain what it is you are trying to do.leaving the bootstrap disconnected will not work. this chip is a half bridge driver. you can not run this at 100% duty cycle nor at 0% duty cycle. there needs to be residual switching for the bootstrap pump to work to create the drive voltage for the top fet.

author: Pack34
author_rank: Frequent Contributor
timestamp: October 23, 2013, 09:40:06 pm
content: I'm looking at implementing an array of H bridges with a minimal amount of source PWM lines. To keep my circuit as small as possible I'm looking at utilizing an H-bridge chip to take care of the motor driving instead of building my own. What I need to supply it are the two source PWM lines to command the internal H-Bridge.I am looking at the LM5106 due to it taking care of dead-timing the H-Bridge input as well as generating the second complimentary PWM. These two PWM channels would then feed into the H-Bridge solution.If I can do this then I'd be able to mvoe forward with a single microcontroller solution as eight channel PWM chips are fairly common but I haven't been able to find a micro that has more than two complimentary PWM channel outputs.Toshiba TB67H301FTG Datasheethttp://www.semicon.toshiba.co.jp/info/docget.jsp?type=datasheet&lang=en&pid=TB67H301FTG

author: Pack34
author_rank: Frequent Contributor
timestamp: November 02, 2013, 02:54:31 pm
content: It looked like it would work on paper but, it's a no-go. Instead of trying to use a one chip solution I decided to just make my own and be done with it.The basics of it is to start with the source PWM signal, say 20kHz, then split the signal using a 2NAND gate and a 2AND gate. The NAND inverts the signal on that branch and the purpose of the AND gate is for timing purposes. After this, each branch feeds into it's own 2XOR gate with one input being delayed using a basic RC circuit. According to the basic simulation tool I used, it seems like it should work.Thoughts?
LM5146-Q1: UVLO doesn't get activated until the power source is restarted. - Page 1
Forum section: electronics / projects

author: ElectroAJ
author_rank: Newbie
timestamp: September 28, 2020, 10:02:22 am
content: For the IC LM5146 Upon reaching the UVLO voltage set by the external resistor divider (which generates 1.2V at the UVLO pin upon reaching the desired cutoff voltage) the buck is still operational until the input power source is restarted and a similar thing happens in the case of recovering from UVLO. The buck is not enabled even after the input voltage is raised above UVLO unless the input power source is restarted.

author: exe
author_rank: Unknown
timestamp: September 28, 2020, 12:39:40 pm
content: Did you measure voltage at UVLO pin? The datasheet says it has hysteresis because of 10uA sink. Chances are divider resistors should have a lower value.
LM51772 Buck-Boost controller I2C configuration - Page 1
Forum section: electronics / projects

author: lja246
author_rank: Contributor
timestamp: February 20, 2024, 01:34:32 am
content: Hi all,I'm planning on making a high power dc-dc buck boost converter mainly for powering LEDs and I found the LM51772 from TI which looks good. In order to configure different settings on the IC you use resistors on different pins but two of the configuration pins are also used for the I2C when its enabled. As I want to use the I2C on this chip i'm not sure how to configure it.I was wondering if anyone else has had any experience with this controller or if you've used other IC's that are configured in a similar way?Or if anyone has suggestions for a different Buck-Boost controller with similar specs? ideally has I2C communication.I've attached a screenshot of the section from the datasheet where it talks about the CFG pins.

author: tooki
author_rank: Super Contributor
timestamp: February 21, 2024, 08:58:47 am
content: I started looking at it, and I have to say that is by far the worst data sheet I’ve ever seen from TI.Have you also looked at the evaluation board? Those (or their documentation) sometimes explain things more clearly and succinctly than the data sheets.https://www.ti.com/tool/LM51772EVM-HP

author: lja246
author_rank: Contributor
timestamp: February 21, 2024, 10:41:58 am
content: For people who don't want to look at the datasheet the CFG3 and CFG4 pins which are used to configure different settings for the IC are shared with the I2C SCL and SDA pins.After looking at the evaluation board I think that if you plan on using I2C with the IC then you just use CFG1 to enable I2C and then ignore any resistors for the R2D circuit on CFG3 and CFG4 for the IC settings. Just use a normal pull up resistor for normal I2C operation and then the settings which previously had to be configured using the pull down resistors on CFG3 and CFG4 can be changed using I2C.I'm still not sure if this is actually how it works and as you've seen the datasheet is kind of a mess at the moment and I can't justify paying $400 AUD for an evaluation board. As it is a new IC there isn't any documentation on it other than the unfinished datasheet.I might have to wait until there is more information or just find a different DC-DC converter.
LM5642 BUCK CONVERTER NOT WORK - Page 1
Forum section: electronics / projects

author: SILVESTROS13
author_rank: Newbie
timestamp: December 01, 2019, 06:15:57 pm
content: Hello to all !getting some info from AN1292 (Texas application for LM5642 ),I made dc-dc converter to use at a solar controller. At test with no load the converter not work . no output, no pulses 200khz to drive mosfets. it seems to be disable ( on/ss pins below 2volts ). I was checked hardware for errors many times , but I don't find something. The measurements shows that ic is ok , but something disable output. Any idea for possible reasons ?

author: Xenoamor
author_rank: Regular Contributor
timestamp: December 02, 2019, 01:36:50 pm
content: Does it operate with a load?

author: SILVESTROS13
author_rank: Newbie
timestamp: December 02, 2019, 03:02:15 pm
content: Xenoamor,no, the converter works as voltage regulator with feedback control. So, there is no need load to set the output voltage. The converter remains in disable mode for some reason that I try to find.

author: deskpro256
author_rank: Contributor
timestamp: December 07, 2019, 10:24:05 am
content: QuoteIf I understand correctly, the SS1 and SS2 pins need to be HIGH for the outputs to work. According to your measurements, those pins are below 1.2V, hence the chip is in shudown mode.Others? Does that seem right?
LM7171 taking a lot of current - Page 1
Forum section: electronics / projects

author: hammil
author_rank: Regular Contributor
timestamp: March 27, 2013, 10:06:03 am
content: So I bought a couple of LM7171 high-speed op-amps, and hooked up a simple follower circuit, with a +/-15V supply (specced in the datasheet).For some reason, the damn thing was drawing tens of mA with nothing connected (despite a 6.5mA suppy current spec) and heating up pretty badly. Inputting a signal however... it drew something like 100mA and got pretty toasty.The pinout is the standard op-amp layout, with all non-essential pins marked NC. I can replace the chip with a TL081 in the exact same circuit and it works fine.. What's more, replacing the chip with another identical one doesn't have any effect. It seems to be an integral problem...Thoughts, anyone?

author: oPossum
author_rank: Super Contributor
timestamp: March 27, 2013, 10:15:35 am
content: Most high speed op-amps can't be used as a unity gain voltage follower - they will oscillate. Try a gain of 3 or more.

author: blackdog
author_rank: Frequent Contributor
timestamp: March 27, 2013, 10:42:30 am
content: Hi hammil,The minimum gain of a LM7171 = +2You cant load a high speed opamp capacitive, use a small resistor on the output to measure, 10 to 100 Ohm.Reed about decoupling, verry inportant!Regarts,Blackdog

author: hammil
author_rank: Regular Contributor
timestamp: March 27, 2013, 12:11:34 pm
content: Ah, I see.. Interesting. Thanks for the help

author: Coyote
author_rank: Contributor
timestamp: August 16, 2017, 08:58:50 pm
content: In the datasheet of LM7171 there is an application note like instrumentation amplifier, where the difference amplifier has a gain of 1, resistors are all the same 1k. Now, would such difference amplifier also oscillate or cause troubles? What is an alternative opamp to LM7171, preferably with null offset adjust?
LM723 and Variable Current Control Technique???? - Page 1
Forum section: electronics / projects

author: Gurumurthy
author_rank: Regular Contributor
timestamp: June 17, 2017, 07:02:30 pm
content: Hi to all!!This was a circuit Discussed in our Forum Last year.the doubt is first circuit , how does the current control knob operates that is 1Kohm 10 turns potentiometer in the first circuit?the second circuit contain potentiometer of 500ohm which control the current in output of regulator Circuit?the third circuit contain potentiometer accross a Diode, How does it make Current variable regulator?Please help me in such way i could understand Variable current control circuit LM723 Voltage regulator.I have also Discussed this in my previous thread topic, current limiting is not happening in LM723???...So i am totally confused with these circuit. Please make me to understand the Technique behind Current control transistor in LM723 for Variable current control in power supplies..Help me in this regard.. I think i have conveyed my thoughts.if any thing is incomplete . Correct me if i am wrong..

author: Kleinstein
author_rank: Super Contributor
timestamp: June 17, 2017, 07:32:35 pm
content: The Current limit in the LM723 engages with more than about 0.6 V between pins 2 and 3. In Circuit 3 the ampmeter is used as a shunt for the current limit. So it would not work well without. The pot reduces the voltage of the diode and the shunt a little to set a higher current limit. Due to the diode the characteristic is a little nonlinear and can work with a relatively low drop on the shunt. The nonlinear curve is in a good sense more like a log scale for the current. So the current limit can be set to low values. However thermal stability sets a practical lower limit, as the diode and LM723 internal transistor will have different temperature.The first circuit works rather similar. The difference is that the base to emitter drop of the output stage is used instead of the extra diode. With the two diode drops, the adjustment can go all the way to zero. However thermal drift can be a bigger problem than with the 3rd circuit.The Circuit 2 is a little tricky. Here one a shunt is used to make up the drop. The additional pot as a divider increases the point where the current limit sets in even more. So only a moderate adjustment range is practical - with higher setting there will be a lot of power loss at the shunt. So this not a really practical circuit.

author: Gurumurthy
author_rank: Regular Contributor
timestamp: June 18, 2017, 01:39:51 am
content: HI Kleinstein,In circuit 3, the voltage accross the diode is say 0.7V . The current control transistor , base emitter pin is at 2 and 3 which has cut in potential of 0.65. hence a difference of 0.05 is going to do the current control with the help of pontentiometer.whether my thinking is correct. Correct me if i am wrong..

author: Gurumurthy
author_rank: Regular Contributor
timestamp: June 20, 2017, 06:19:58 am
content: Dear Sir,What are the ways to monitor current and Design a Variable current control Power Supply. Teach me the way or give some references from books.
LM723 Negative Voltage Regulator - Higher currents, + Current Limiting? - Page 1
Forum section: electronics / projects

author: fivefish
author_rank: Frequent Contributor
timestamp: August 02, 2015, 11:45:02 am
content: I'm trying out a 723 negative voltage regulator circuit for 1st time.The Positive voltage regulator in datasheet shows how to set current limit.But for their negative voltage regulator (Fig. 18), there is no provision.How do you set current limit value in a negative regulator schematic?

author: SeanB
author_rank: Super Contributor
timestamp: August 02, 2015, 12:08:33 pm
content: Add an external PNP transistor to operate to steal base current, just like the NPN version does. Connected between base of the pass device and emitter, like the positive version, with a sense resistor.
lm78xx series question and some more stuff - Page 1
Forum section: electronics / projects

author: Kilroywashere
author_rank: Regular Contributor
timestamp: January 23, 2020, 12:47:23 am
content: Hello world,I'm building a lab power supply and I only have 1 Lm317, I want to have a current limit of up to 1 amp . I know that you can use a 78xx series to provide a constant output current, I was wondering can I just use a 7805 as my current regulator or will 1 amp be too much for this thing to handle ? (get super hot and such) I wanted to save the Lm317 for the voltage adjustment, or is it better to use it for current if you only have one?Also some designs I look at have two 1n4001 diodes and a transistor leading into -10volts (I guess to bring the output to 0 v?) is it better to have some sort of duel + - power rails powering the thing?

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 23, 2020, 07:27:11 am
content: Quote from: Kilroywashere on January 23, 2020, 12:47:23 am- yes.

author: MarkF
author_rank: Super Contributor
timestamp: January 23, 2020, 01:05:36 pm
content: Do you want to just limit the current to 1A or do you want an adjustable current limit?If you want an adjustable current and are okay with a minimum of 1.2V of the LM317,you can do something like this:If you just want a fixed 1A current limit,take a look at this battery charger circuit:The sense resistor value can set a fixed current limit with the minimum LM317 voltage output.You will probably want a full-wave bridge and a large cap for the input. But you get the idea.(You can use any NPN transistor, 2N2222, 2N3904, etc. But will need to select a different sense resistor value.)Quote from: Kilroywashere on January 23, 2020, 12:47:23 amYou only need a negative if you want to pull the minimum output voltage down to 0V.

author: MarkF
author_rank: Super Contributor
timestamp: January 23, 2020, 01:13:43 pm
content: A LM317 circuit that goes down to 0V.
LM8363 clock - converting direct drive to MUX possible? - Page 1
Forum section: electronics / projects

author: Electro_Alex
author_rank: Newbie
timestamp: November 20, 2024, 11:29:36 am
content: Hello,I have an old VFD clock with LM8363. Unfortunately the display broke and I dont have a „static drive“ VFD as a replacement.But I have a multiplex drive type VFD laying arround which would fit perfectly.Even the grid/anode voltages are nearly identical.Since the LM8363 has discrete outputs for HH:MM:SS it drives each segment (20 segments) individually. There is just one grid.My new VFD needs to be multiplexed, because it just has 7 segments (which are all interconnected which other) but 5 grids.Is there a way to generate the needed multiplex signal (with for example shift registers?) from the 20 outputs of the LM8363?Would it be very diffucult or doable?Unfortunately I cant find any info how this could be done (a hint, how it would work in theory would help a lot).I dont want to replace the whole clock IC with any kind of microcontroller (this would be a more common solution, I know) but I want to keep the original electronic as much as possible.Thank you very much for your help.Best regardsAlex

author: PCB.Wiz
author_rank: Super Contributor
timestamp: November 21, 2024, 09:07:59 pm
content: Quote from: Electro_Alex on November 20, 2024, 11:29:36 amSomewhere in the middleThat many digits can not be driven non-mux from 20 pins, and data suggests they use a mains half cycle multiplex scheme on the LM8363 for HH:MM:SSThat means you need to sniff those pins, and demux the contents, then re-mux onto your display.A simple MCU is the best way to manage that, it could just use level shifters, if it has enough pins.eg If we look for 'modern DIP' (a bit of an oxymoron) I see lcsc have stocks ofAI8051U-34K64-PDIP40, that new part has a USB loader inbuilt, and is in easy to use DIP40, it might just fit with level shifters alone.STC8H8K64U-45I-SKDIP28 smaller sibling SKDIP28, that could use a VFD serial shift registerYou can also buy modules with these MCU fitted from Aliexpress.AVR mcu also come in DIP.Quote from: Electro_Alex on November 20, 2024, 11:29:36 amNo colons or decimal points to flash every second ? 5x7 comes up short for HH:MM:SS ?
LM86E - information about this component requested - Page 1
Forum section: electronics / projects

author: atsthng
author_rank: Contributor
timestamp: June 01, 2014, 04:06:34 pm
content: I'm trying to find out what this component - LM86E - is. A picture is attached.I was attempting a repair where I narrowed the problem down to this component overheating and pulling down a voltage rail. Most of the components on the board are circa late 1990s.The component label on the PCB is "TS". No schematics; one end is connected to ground, the other to a diode to the voltage rail, and likely something else.The usual suspects, Google, digikey, the component search engines, all point to LM86, which is a thermal management IC (8pin).I'm guessing it is some form of thermal sense diode based on the PCB label, and the component packaging. However, I would appreciate a pointer to more information, possibly a data sheet.

author: Bored@Work
author_rank: Super Contributor
timestamp: June 01, 2014, 05:53:01 pm
content: SMBJ15A unidirectional transorb. Several manufacturers. The particular one is from General Semiconductor, these days a Vishay brand.

author: atsthng
author_rank: Contributor
timestamp: June 01, 2014, 06:11:19 pm
content: Thank you very much!
LMH6518 Alternatives - Page 1
Forum section: electronics / projects

author: Sariel
author_rank: Regular Contributor
timestamp: October 30, 2023, 04:41:57 pm
content: Hey,I am about to design a circuit that is similar to oscilloscope's front end.I am inclined to use the LMH6518 since I need variable BW in addition to variable gain.As much as I dug in TI and AD sites, I couldn't find additional parts with variable BW.Are there any other alternative devices or circuits out there to LMH6518?Thanks
LMR16006 step down regulator circuit - Page 1
Forum section: electronics / projects

author: anvoice
author_rank: Frequent Contributor
timestamp: August 31, 2018, 01:45:03 am
content: Trying to design a circuit using the LMR16006 step down regulator. TI has software that helps you calculate which components to use (http://www.ti.com/product/LMR16006/technicaldocuments, under tools and software, though requires a potentially vulnerable java plugin to run). However, my circuit will likely draw no more than 50ma, and the software states the regulator will be unstable even at 100mA. In addition, the chart showing efficiency in the datasheet shows 100mA as the minimum value, with a 60% efficiency to boot.Is my understanding that this buck converter is unusable for my application correct, or can I make it work somehow, with low efficiency perhaps?

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 04, 2018, 04:10:04 pm
content: It won't be unstable if you make the pcb right.it will get a little hot thats all.it says it works at 1 mA on first page, just the efficiency is smaller, that's crystal clear.You can read datasheet and decide yourself the components, you'll never use what the calculator gets you.I never do...and it works.But if you want, the online calculators are not bad to avoid beginner errors for capacitors or inductors, I remember once Iput 10uF and changed to 100 cause I use stupid enough not to check with a simple tool like those online calculators.So, calculate the components, check with datasheet the C series resistence specs and watch out for a goob pcb ground between chip, capacitors and inductance.My ex-boss did some beginner errors on pcb side and at testing we had popcorn chips all over the place.Regards,pierreEnvoyé de mon iPad en utilisant Tapatalk

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 04, 2018, 04:13:29 pm
content: Sawed you have in datasheet a layout example but imho it's ugly and can be done better (I did the same 2 weeks ago with some ap1509, a cheap dcdc chip)Envoyé de mon iPad en utilisant Tapatalk
LMR16006 voltage ripple issue - Page 1
Forum section: electronics / projects

author: uer166
author_rank: Super Contributor
timestamp: September 19, 2019, 02:13:30 am
content: I've never had issues with TI Webench online tool before but lately it's been either misleading, or maybe I'm reading it wrong. Seems like the more time I spend trying to design a power supply the more it sucks..Goal is a 48V->3.3V supply at 300mA, nothing hard. Attached circuit. According to the TI tool I remember the output voltage ripple being <10mV. But, what seems is the controller works in bursts: bursts a couple pulses, inductor goes to 0 (DCM), then rinse and repeat. While the voltage ripple during the pulses is well under 10mV (I mean it operates at 2.1MHz), the second-order ripple due to this bursty behavior at around 100KHz is something like 200mV, completely unusable for my application.I don't see how the above could be an issue with ECO mode since this persists even at 600mA full output current. Only thing I can think of is there is a minimum ON time on the switch which happens to generate a voltage above 3.3V, enforcing burst mode?I even double checked the output ripple voltage and other parameters using the datasheet provided equations.. So what gives? The layout is plenty tight, almost no visible ringing during the switch transitions (except low energy ringing whenever inductor current reaches 0, as expected).

author: thinkfat
author_rank: Unknown
timestamp: September 19, 2019, 09:25:35 am
content: The only odd thing I saw is that Cbootseems mighty large at 1µF, typically that's in the 100nF range. But I'm not sure if that would cause such behavior.

author: mikerj
author_rank: Super Contributor
timestamp: September 19, 2019, 12:59:24 pm
content: I think the problem is that you are dropping a lot of voltage, which requires a low switch duty cycle (3.3/48=6.9%). If I'm interpreting it correctly the datasheet shows the minimum on time at 2.1MHz is 80ns, giving a minimum duty cycle of 16.8%. Using the 700kHz part (with appropriate value inductor) would help.
LMX2582 sine or square wave output  (RF Synthesizer with Integrated VCO) - Page 1
Forum section: electronics / projects

author: sorin
author_rank: Frequent Contributor
timestamp: May 15, 2016, 03:47:37 pm
content: Please can anyone tell me what output should have this Synthesizer, sinewave or squaewave?Ther are 2 type of outputs, direct from VCO and the other from the counter outputCan we use this Ic as a signal generator?Thanks in advance!http://www.ti.com/product/lmx2582Datasheet:http://www.ti.com/lit/ds/symlink/lmx2582.pdf

author: danadak
author_rank: Super Contributor
timestamp: May 15, 2016, 07:02:53 pm
content: The output of the VCO is a squarewave, the counter out a pulsewith varying duty cycles depending on /n and fractional dividerlogic.If you want a Sine, Triangle, Saw, Square then a DDS chip more appropriate.http://www.analog.com/en/products/rf-microwave/direct-digital-synthesis-modulators.htmlRegards, Dana.

author: SaabFAN
author_rank: Frequent Contributor
timestamp: May 16, 2016, 01:33:21 am
content: I doubt there is a cost-effective DDS-Solution available that can generate a sine-wave in the 5Ghz-Range.A sine-shaping circuit to turn the square-wave into a sine-wave would probably the best solution.TI has an application-note about that topic.
LMZM23600V3SILT - what are the likely gotchas? - Page 1
Forum section: electronics / projects

author: peter-h
author_rank: Super Contributor
timestamp: May 06, 2025, 10:06:43 am
content: This is an amazing tiny stepdown switcher.I've been doing switchers for about 40 years and would expect this one to radiate like hell - both radiated and (especially) conducted.OTOH its plus is the compact size so radiating loops would be minimal.The DS recommends a sizeable input cap, only.https://www.ti.com/lit/ds/symlink/lmzm23600.pdfThey now recommend this onehttps://www.ti.com/lit/ds/symlink/tpsm365r6.pdfand looking at that having spread-spectrum, I reckon TI bit off more than they could chew with the earlier one
LNA DESİGN  - Page 1
Forum section: electronics / projects

author: joyboy
author_rank: Newbie
timestamp: May 20, 2021, 01:34:14 pm
content: Hello I'm working on some project about LNA.I need your help with the matching my Transmission Lines in my LNA Design project.You don'T have to tell me the values or anything I just want to know how to match them so that I get my desired Gain from the LNA for my project.Currently I get around 7db gain for 5 to 6GHz frequency I attached my design as 2 screenshots because its too big I hope u can help me.Thanks in advance.

author: joyboy
author_rank: Newbie
timestamp: June 16, 2021, 01:49:27 pm
content: up
LNK306 based AC-DC converter does not work - Page 1
Forum section: electronics / projects

author: electrotwelve
author_rank: Contributor
timestamp: May 29, 2016, 04:32:07 pm
content: I've been following theAN37guide to build a non-isolated +/- 3.3V power supply. Attached here is the schematic as well. for the inductor I chose a 1mH inductorsimilar to this. The line filter capacitors are 4.7uF/450V. The first time I powered on the circuit the 1mH inductor blew. I replaced that with a 470uH inductor much likethis one. This time the chip blew. What is going wrong here and how do I fix it?

author: ebclr
author_rank: Super Contributor
timestamp: May 29, 2016, 05:33:13 pm
content: Try to put a small Resistor 8.2R 2W in series with input or even better a inrush NTC Like page 4 of the datasheet

author: electrotwelve
author_rank: Contributor
timestamp: May 29, 2016, 06:31:49 pm
content: Thanks folks. What kind of inductor would be suitable for the AC line filter section?

author: ebclr
author_rank: Super Contributor
timestamp: May 29, 2016, 09:09:51 pm
content: Your answer is on the page 5 of AN 36 that you refereed, there is a table with models according to your configuration