hybridfree/eevblog-posts huggingface dataset:
LT1006 follower/buffer - Page 1
Forum section: electronics / projects

author: staze
author_rank: Frequent Contributor
timestamp: May 24, 2014, 02:45:33 am
content: All,Hopefully a quick/easy question. I'm using an LT1006 as a buffer for the voltage control on an OCXO, and it seems to work fine, but one thing that I'm wondering about is in the datasheet for the 1006, they show a 600R resistor from the output to ground. Why?Datasheet:http://www.redrok.com/OpAmp_LT1006_50uV_Precission-Single-Supply_Single.pdfFrom the datasheet, it says the LT1006 output can sink current, so I don't see why you'd need to provide the path to ground.Anyone?

author: c4757p
author_rank: Super Contributor
timestamp: May 24, 2014, 03:04:52 am
content: It "can" sink current, but check the data. When sinking only 1mA, the output won't go below 0.22V. The 600 ohm load increases the low-end output swing significantly.

author: staze
author_rank: Frequent Contributor
timestamp: May 24, 2014, 03:10:15 am
content: okay. so, then, the 131-100 has a 100kR input impedance... should I still be okay using that 600R, or should I up that to something a bit higher? Seems like I'd be wasting a bit of current with a 600R resistor in there. Though... obviously the OCXO is always going to be my highest draw.

author: c4757p
author_rank: Super Contributor
timestamp: May 24, 2014, 03:13:04 am
content: How low do you need the output voltage to go?Quote from: staze on May 24, 2014, 03:10:15 amBingo. You won't miss a handful of mA here or there.

author: staze
author_rank: Frequent Contributor
timestamp: May 24, 2014, 03:25:04 am
content: Though, don't stock 600R resistors. 1k work, or should I shoot for lower?

author: c4757p
author_rank: Super Contributor
timestamp: May 24, 2014, 03:35:38 am
content: 1k will probably work just fine. Otherwise, 620 or 560.

author: staze
author_rank: Frequent Contributor
timestamp: May 24, 2014, 06:12:21 am
content: had a 680 1% in my box... that seems to work just fine.Mind you, I never have the input to the amp that low, but it shouldn't be a problem. Guess we'll have to see when I build the rest of the PLL.Thanks!

author: David Hess
author_rank: Super Contributor
timestamp: June 01, 2014, 05:31:04 am
content: The datasheet does not say it directly but the resistor is only needed to prevent the output stage from saturating when operating close to the negative rail. I doubt there is any reason for you to include it.As a practical matter, driving a low output resistance will compromise the precision of the operational amplifier.

author: staze
author_rank: Frequent Contributor
timestamp: June 01, 2014, 09:46:19 am
content: *nods* seems to work fine with the one I put in. I threw in a 600R with my growing mouser order so it can be "spec". Don't see why there might be a case where the amp may have to go toward ground when the ocxo goes a bit too high. Better safe than saturated.
LT1027 based Reference Voltage - Page 1
Forum section: electronics / projects

author: iTist
author_rank: Contributor
timestamp: February 09, 2014, 10:25:22 pm
content: Hi,beside the two killer Reference Voltage threads, i would like to present my little voltage reference for beginners.It is an unbufferd 5V reference based on the LT1027. I use a LT1763 as low noise regulator which is fed by a linear 15V power supply.I put it all in a metal case and thermal Chamber made of styrofoam with an build in heater.More details and some measurements at:http://itist.de/2013/09/lt-1027-basierte-5-v-referenzspannungsquelle/GreetzOliverThe LM399s were waiting......

author: cellularmitosis
author_rank: Unknown
timestamp: February 10, 2014, 02:10:00 pm
content: neat! what are you using as a heater circuit?edit: ah, I see the PTC heater foil used as the heating element in your blog post. But how are you measuring / regulating the temperature?

author: iTist
author_rank: Contributor
timestamp: February 10, 2014, 07:21:35 pm
content: Hi,I am using a Thermocouple Type K for the temperature measurement.The Foil is "self regulating" via its PTC characteristic.I plan to build a temperature control with an KTYxx and an OpAmp but first I have to measure the real temperature of the case.My target is around 32° C because the maximum ambient Temperature is 26°C. Maybe i need another heater (Ceramic Resistors).GreetzOliver

author: Nuno_pt
author_rank: Frequent Contributor
timestamp: February 10, 2014, 07:40:26 pm
content: Try this as a heater, it's at 40° C but very stable.http://www.kuhne-electronic.de/en/products/crystal-heater/qh-40-a.html

author: branadic
author_rank: Super Contributor
timestamp: February 10, 2014, 07:54:34 pm
content: QuoteMy guess is, that this heater (QH40A) is a bit to small for this application. But I can confirm that it is a neat little beast.I have it assembled on my chip resistors (only 5ppm/K) of my LM399 reference and on a MAX6325 in plastic package. The heater is only somewhat bigger compared to a SO8 adapter board.

author: iTist
author_rank: Contributor
timestamp: February 10, 2014, 09:36:54 pm
content: QuoteHi,I think that's true but this was for a first cheap test. Is the QH 40 suitable for the whole metal case ore only for the reference IC? Could i order it at Kuehne electronic or is there a distributor?Thanks.GreetzOliver

author: branadic
author_rank: Super Contributor
timestamp: February 10, 2014, 09:58:50 pm
content: QuoteOnly for the reference. The heater is only 10,5mm x 14,0 mm in size, operating voltage 8 ... 12V and about 80mA inrush current.

author: iTist
author_rank: Contributor
timestamp: February 10, 2014, 10:11:16 pm
content: Okay,i used the foil for the whole case it draws 180mA at 12V and i got a temperature difference of approx. 18°. I haven't done the math.Need a more precise thermometer. Maybe a sensor with I2C bus?GreetzOliver
LT1028 noise modelling in LTSPICE - Page 1
Forum section: electronics / projects

author: splin
author_rank: Frequent Contributor
timestamp: April 01, 2016, 09:14:46 pm
content: I was just having a go at noise modelling in LTSPICE but am rather confused by the results. The circuit and noise results are attached. LTSPICE calculates the .1 to 10Hz noise to be 873,43nV rms which, as expected, is almost alll due to the input noise current in the 10k resistor. It gives the same result if the 1 ohm and 10k are swapped.However if both resistors are set to 10k the output noise drops to 613.45nV. Can anyone explain why - I was expecting it to increase by approx sqrt(2)?

author: Marco
author_rank: Super Contributor
timestamp: April 01, 2016, 09:58:52 pm
content: I suspect the modeled current noise for the two inputs has high correlation (presumably caused by the current source for the differential pair input stage) and thus sums out when the source resistances are equal.

author: splin
author_rank: Frequent Contributor
timestamp: April 01, 2016, 10:22:03 pm
content: Thank you both - I just assumed that they would be uncorrelated.Ironically I had (skim) read that note on page 11, but it was a long time ago and I didn't really understand it at the time - it now makes sense! Very clever of LTSPICE to model it correctly.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 01, 2016, 11:47:16 pm
content: A "gotcha for young players", amps with input bias current cancellation. There's a paragraph about it in AoE3: the input current noise is much higher than the shot noise from the input bias current. For these, obviously you need to keep Rsrc under 10k or so (preferably under 1k), but much more importantly is to keep the resistances matched.Tim
LT1185 as positive regulator with floating ground - Page 1
Forum section: electronics / projects

author: the Chris
author_rank: Regular Contributor
timestamp: June 21, 2024, 03:57:29 am
content: I accidentally ordered LT1185 instead of LT1085 and was wondering if it still could fullfill the intended job.I would like to build a simple battery pack for my motorized equatorial telescope mount. It is currently being driven by a 12V DC 2A power supply. I did some measurements and found out that the tracking consumes no more than ~350mA and that even by fast forwarding multiple axis I could not get past 0.9A. I didn't want to lug around the manufacturers pack with 8 mono D cells as I won't use the capacity and rechargeable ones with low self discharge are hard to come by. Therefore, I bought an empty pack for four 18650 cells and four LiFePo batteries which should be regulated to 12V by the LDO LT1185. I expect the usable effective capacity to be somewhere around 1500mAh which would be OK for the restricted time I have at hand for nighttime observations. I don't mind recharging after one session.The datasheet of the LT1185 mentions the option to use it as a positive regulator for a floating ground application. To me, it looks like this is the case here and that I just need to invert input polarity of the reference design to gwt the job done. The regulator would only see the attached motor controller and no other voltage sources.Am I missing something here or do you thing this should work out?https://www.analog.com/LT1185/datasheetThanks for help,Christian

author: Someone
author_rank: Super Contributor
timestamp: June 21, 2024, 04:21:02 am
content: Quote from: the Chris on June 21, 2024, 03:57:29 amAs long as the batteries are not connected to anything else at the same time (which risks bypassing the regulator).
LT1210 based power-amplifier for function generator - Page 1
Forum section: electronics / projects

author: charliehorse55
author_rank: Contributor
timestamp: August 22, 2025, 09:17:34 pm
content: I'm working on a power amplifier for my function generator (Siglent SDG2122X). I have run into a few use cases where it'd be nice to have a very low impedance source. After some research, I came across the LT1210. It seems well suited for the task, especially when used in parallel. Expanding on a reference design in the LT1210 datasheet, I came up with this:And each channel:To power it, I'm looking at using 2x 15V/10A Meanwell supplies (https://www.mouser.ca/ProductDetail/709-LRS150F-15)Some design notes:The 500mOhm output resistors balance the current due to offset voltage differences in the LT1210s. A maximum of 40mV offset voltage gives 80mA, but more typically it's +-3mV for +-6mA eachThe LM7171 has a gain of 2, so that when selecting High-Z mode on the function gen the voltage will matchThe 255 ohm resistor on the input balances the input impedances of the op-amp to minimize offset voltage due to bias currentsSimulated bandwidth is about ~23 MHz -3dB, primarily limited by the input filter. This gives it a nice, smooth response across a variety of output loadsMaximum output capacitance is determined by the the RC pole frequency with the output resistors. 10nF gives ~200 MHz, which is above ~100MHz bandwidth of the 1210A few questions:Bypassing capacitors have not been added yet - how to design this? How low of a frequency range needs to be bypassed before the PSU can cover it? I think I will need tantalums in parallel with ceramics, are there any tricks to make sure you don't get parallel resonance among the dissimilar capacitors?I used a 220 ohm feedback resistor, which is lower than mentioned in the datasheet. However, it didn't seem to cause any problems in simulation, even with an added gaussian noise term. If the resistor is <50 ohms, the sim shows problems with stability. I'm not sure how to analyze the phase margin of this combined op-amp setup.Any other design notes?
LT1763CS8 family LDOs - fixed vs. adjustable? - Page 1
Forum section: electronics / projects

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: February 12, 2021, 01:42:54 am
content: I've been reviewing a reference design for a particular ADC that requires four supply voltages. For the three positive ones (+15, +5 and +3.3V), they use the same adjustable LT1763CS8 LDO with the corresponding resistor divider values to get the voltages. But the LT1763CS8 also comes in fixed voltage versions including for +3.3V and +5V. So, I'm curious why they would choose the adjustable version. Is there any technical benefit? It seems a waste of two extra high precision resistors and more pads on the board for each LDO. For mere mortals, they are the same price on Mouser etc.https://www.analog.com/media/en/technical-documentation/data-sheets/1763fh.pdfhttps://www.analog.com/media/en/technical-documentation/eval-board-schematic/DC2365A2-SCH.PDF

author: KE5FX
author_rank: Super Contributor
timestamp: February 12, 2021, 02:02:22 am
content: The adjustable LDO can save a BOM line item, if you need more than one voltage and happen to have existing resistors somewhere on the BOM that will work. (Or, more likely, if you can use the same resistors somewhere less critical, in place of standard values.)Then there's always the chance that you need an unsupported voltage, although for these low current point-of-load parts that seems pretty unlikely. They cover all the common ones from 1.5V to 5V.There is a slight drawback to parts like this that use the same part # for different pinouts/functions, in that it is asking for trouble at the assembly house. I've had that happen with the LT1965 regulator, which works the same way. I used one each of the 1.2V, 3.3V, and adjustable versions on the same PCBA. They ran out of one and (fortunately) asked me if they could use another in its place. It would have been smarter, and possibly cheaper, if I had used the adjustable version in all three places, as it sounds like your reference design did.A bad policy on the part of the vendor IMO, but they are good LDOs.Edit: another reason might be that itisrare for anyone to use the adjustable version, and LT made too many of them. There might have been some encouragement to use the unwanted parts on their demo boards.
lt3080 lt1965 laser diode driver, feedback? - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: April 26, 2018, 07:11:54 pm
content: I have these two IC's, I know its ridiclous, but I wanted to use them to drive this 100mW green laser diode. Right now it has a simple little driver, but I was gonna add a trimpot and a switch that can be used to regulate it, and a steel enclosure, so I figure I might as well replace the chinese IC's and deadbug a little power circuit directly on the heat sink with the diode.Benefits would be it could run up to 20V or more (depending on the vreg I use) depending on ambient temperatureAnyway, I was thinking of power vs current control. The diode I have does have a feedback diode.I noticed some commercial lasers have a selectable current mode or power mode. Current mode is easy, I just use the LT3080 as a current source.Power mode would mean I would need to get the diode output voltage and route it back into the feedback pin on the LT3080 with a scaling network (voltage divider I guess?) to set the setpoint.Any thoughts on this?

author: elecom
author_rank: Newbie
timestamp: May 30, 2018, 04:51:50 pm
content: Any updated information?

author: CopperCone
author_rank: Super Contributor
timestamp: May 30, 2018, 06:45:48 pm
content: The diode I had was built like a piece of complete shit and minor rotation caused supposedly strain relief bond wires to break so I gave up on the project.The mechanical design on those is garbage, I don't really even want to deal with one until I figure out some kind of nice tidy way to make a socket-like connector for them.And im broke as fuck so I can't go forward. And some how oil got on my optics, and it was all fuzzy.Word of advise : If you are doing machine work for lasers that involves cutting fluids or tapping fluids, I would recommend getting a ultrasonic cleaner (which I don't own) to clean them up afterwords. I did what I could with acetone but not enough.

author: CopperCone
author_rank: Super Contributor
timestamp: May 30, 2018, 06:51:30 pm
content: and that laser had some kind of ridiculous fucking thread, for which I don't have the tools to tap, and the body was positive.I cannot tolerate a positive body. I wanted to earth the chassis.But I did design something using one of those LTC protection circuits thats real nice.I kind of don't want to attempt this project again until I have the money to replenish my welding supplies and make a custom box for it (instead of trying to hack a junction box), and get some kind of laser that has a earthed or floating body.And for power mode, it turns out that the solution commercial manufacturers have is to just use a thermistor on the heat sink, to prevent thermal runaway, which can happen.It's like a tiny thread, meant for like 1/8 inch screws, on a god damn 1/2 inchnot worth my time unless I can make it right, otherwise it will just come out like some cheap garbage
LT3080 LTSPICE Simulation error. (Dave PSU) - Page 1
Forum section: electronics / projects

author: xReM1x
author_rank: Regular Contributor
timestamp: June 29, 2015, 01:14:13 pm
content: I set the current to 1.1Aas you can see, it set the current to 768mA.I have no idea why is that.

author: void_error
author_rank: Frequent Contributor
timestamp: June 29, 2015, 01:47:20 pm
content: Why is R1 shorted?

author: xReM1x
author_rank: Regular Contributor
timestamp: June 29, 2015, 02:07:25 pm
content: Quote from: void_error on June 29, 2015, 01:47:20 pmshorted?still the same thing, it does limit the current, its just not accurate at all.

author: void_error
author_rank: Frequent Contributor
timestamp: June 29, 2015, 02:12:13 pm
content: Try using a LTC6101 for current sensing.

author: xReM1x
author_rank: Regular Contributor
timestamp: June 29, 2015, 02:18:08 pm
content: Quote from: void_error on June 29, 2015, 02:12:13 pmnothing.

author: void_error
author_rank: Frequent Contributor
timestamp: June 29, 2015, 02:51:51 pm
content: You're using it wrong. Check the datasheet first. Your current sense circuit using the LTC6101 should look like this (without the LTC2433):You need RINand ROUTfor it to work.

author: xReM1x
author_rank: Regular Contributor
timestamp: June 29, 2015, 03:09:28 pm
content: Quote from: void_error on June 29, 2015, 02:51:51 pm

author: indole
author_rank: Unknown
timestamp: June 29, 2015, 03:47:07 pm
content: Have a look at the current limit input-to-output differential graph on the datasheet. I have a feeling that dropping 14V is what's causing it to limit it's output current to 800mA.

author: void_error
author_rank: Frequent Contributor
timestamp: June 29, 2015, 03:55:27 pm
content: There's that and there's also the fact that the LT1013 doesn't swing close enough to ground (from the datasheet it can only go down to V- +1V) so the transistor doesn't switch off. You might want to use the LT1368 instead.

author: indole
author_rank: Unknown
timestamp: June 29, 2015, 04:06:03 pm
content: Unless I'm mistaken in reading the LT1013 datasheet, in single supply operation it can swing within a couple mV of ground.Quote

author: void_error
author_rank: Frequent Contributor
timestamp: June 29, 2015, 04:19:55 pm
content: Quote from: indole on June 29, 2015, 04:06:03 pmI was looking at the output voltage swing specified for RL=2k and +/-15V supply which is not the case here, oops...Anyway, xReM1x, here's a version that will work. You had R1 set too low, giving you 0.1V/1A at the output. You could go with an op amp for current sensing but your accuracy will depend on the op amp's input offset voltage and the matching of the four resistors of the difference amplifier. LTC6101 is the easy way here and it will work.EDIT: V3 should be 0.5V not 5V.
lt3080 setpoint higher then supply voltage noise effect - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: June 18, 2017, 03:09:41 am
content: What happens when the setpoint is above the supply voltage (due to a droop).I'm interested in the noise behavior. Does it still have PSRR?( i got unlucky with my transformer).
LT3080 Voltage adjustment - Page 1
Forum section: electronics / projects

author: echen1024
author_rank: Super Contributor
timestamp: September 22, 2013, 04:00:54 am
content: For simpler MCU control, and output down to 0v, I have decided to move away from the LM317 to the LT3080. However, I have some questions about how voltage is adjusted on the 3080. On the 317, I know that it tries to form a 1.25v voltage reference between Voutand Vset, but I have read that the 3080 simply outputs the DAC voltage after an Op-Amp. Please help me as I am new to Op-Amp theory and analog circuits in general. I have a MCP4725 on hand and a 10k 256 wiper digital pot as well.

author: Bored@Work
author_rank: Super Contributor
timestamp: September 22, 2013, 07:05:30 am
content: It is all in the datasheet, really. The LT3080 has a (weak) current source. The current is driven through an external (programming) resistor. This establishes the reference voltage on the set pin. Since the current source is weak, it can be overridden by an external voltage source driven into that pin.Sounds good? Well, the LT3080 and some related regulators have a very ugly failure mode. If the voltage difference between the set and the output pin becomes to high, the thing blows up. Such situations can easily happen during power-up, power-down, short circuit, or when rapidly changing the programming voltage.

author: IanJ
author_rank: Unknown
timestamp: September 22, 2013, 10:11:17 am
content: Just a note:LT1083 adjustable regs (similar operation to LM317) also have a problem whereby if you pull adjust pin to zero V suddenly and then release back to some voltage then output doesn't return. You have to reset the device by power down the input. Not much good when designing a CC psu.Ian.

author: echen1024
author_rank: Super Contributor
timestamp: September 22, 2013, 05:38:16 pm
content: Huh... So what would be a good LDO that can easily be Digitally controlled, in any way possible, and preferably down to 0v...

author: kizzap
author_rank: Unknown
timestamp: September 23, 2013, 05:52:11 am
content: Just use any form of LDO, and drive it with an op-amp that will be able to drive the adjust pin to your negative voltage. I'm considering the LT1085-kizzap
LT3081 Lowest Maximum Limited Current Output? - Page 1
Forum section: electronics / projects

author: KJ-90
author_rank: Contributor
timestamp: December 31, 2016, 03:10:39 pm
content: I was wondering if anyone knows if the Linear Technologies LT3081 voltage regulator can be used with a limit resistor ( Ilim ), below 450 ohms to limit output currents to below 135mA. This would be in the voltage range from 2-8 Vdc for various LEDs, including the UV-C that operates on 6.5-8 Vdc at 60-80mA. The data sheet gives no minimum value for Ilim, and just says that a typical value is no less than 450 ohms. What would happen with lower values of current limiting resistors? The Rlim equation is also written in a confusing manner.

author: StillTrying
author_rank: Super Contributor
timestamp: January 01, 2017, 07:38:06 pm
content: Quote from: KJ-90 on December 31, 2016, 03:10:39 pmAs I understand it, you don't need to go below 450 ohms because the programmed output current is already down to zero at 450 ohms.The typical ratio of current limit to resistor value is 360mA/k? with a 450 ohm offset.For 135mA I make it. 135mA = 135/360 kohm + 0.450 kohm = 0.825 k
LT3086 regulator -current boost - Page 1
Forum section: electronics / projects

author: IconicPCB
author_rank: Super Contributor
timestamp: March 20, 2019, 12:03:41 am
content: Are there any attempts to boost the current capability of LT3086?If so are there any gotchas?

author: RES
author_rank: Regular Contributor
timestamp: March 20, 2019, 11:25:01 am
content: https://www.analog.com/en/design-center/reference-designs/circuit-collections/lt3086-paralleling-two-regulators-for-5v-4-2a.html#cc-overviewhttps://www.analog.com/media/en/technical-documentation/data-sheets/3086fb.pdf

author: IconicPCB
author_rank: Super Contributor
timestamp: March 20, 2019, 08:00:26 pm
content: Thanks RES,I am aware of parallel operation of the regulator.I am thinking of an additional external current boost transistorso as to retain the nice features of the regulator but increase current from 2.something amps up to 50 amps.

author: battmyrne216
author_rank: Newbie
timestamp: March 21, 2019, 03:15:59 am
content: 50 amps is crazy what are you trying to do? build a welder?

author: IconicPCB
author_rank: Super Contributor
timestamp: March 21, 2019, 03:45:36 am
content: Radio coms room... switch mode power supply is likely to affect the noise floor of the room.It needs to be linear power supply.
LT3094 input diode - Page 1
Forum section: electronics / projects

author: cape zoloh
author_rank: Contributor
timestamp: July 31, 2020, 09:48:24 am
content: I'm currently constructing a bipolar power supply based of the LT3045 and LT3094.I don't want to use the "Power Good" function, but I still need reverse input protection. This is lost if not using the function, but"if reverse input protection is additionally required, tie the anode of a 1N4148 diode to IN and its cathode to PGFB"- Page 12, LT3045 datasheet. The schematic for this to go with the text is located on page 28, the last figure, I've also attached it as an image.I'm trying to find the equivalent solution for the LT3094, but it is not mentioned in the datasheet. This is where I need your help.LT3045 datasheet:https://www.analog.com/media/en/technical-documentation/data-sheets/LT3045.pdfLT3045 datasheet:https://www.analog.com/media/en/technical-documentation/data-sheets/LT3094.pdf

author: exe
author_rank: Unknown
timestamp: July 31, 2020, 11:54:30 am
content: What do you mean by reverse input protection? Do you expect input wires to be swapped?Anyway, you can add a diode at the input for protection (this will increase dropout by 0.7-0.8V).

author: cape zoloh
author_rank: Contributor
timestamp: July 31, 2020, 03:38:13 pm
content: Yes, I need reverse input protection without the voltage drop of putting one in series, which is possible with the LT3045. I wonder how to do the same thing with the LT3094.

author: exe
author_rank: Unknown
timestamp: July 31, 2020, 06:17:47 pm
content: Quote from: cape zoloh on July 31, 2020, 03:38:13 pmNo, lt3045 doesn't have a diode in series with the input. The diode there does something else.

author: David Hess
author_rank: Super Contributor
timestamp: July 31, 2020, 06:58:30 pm
content: The LT3045 has built in reverse input protection because the PNP output transistor has a high base-emitter breakdown voltage and its collector is isolated from the substrate. The LT3094 does not because the NPN output transistor has a low base-emitter breakdown voltage and its collector is not isolated from the substrate.The only reason to have reverse input protection is if the input can be shorted, like with a crowbar circuit. Usually it is sufficient to put a power diode across the input-to-output to limit the reverse voltage across the regulator to a low value and this is commonly seen on 3-terminal linear regulators for exactly this purpose. For the LT3094, a big schottky diode should be used because of the substrate diode but may be this will not be enough.
Lt317 problems  - Page 1
Forum section: electronics / projects

author: House91320
author_rank: Regular Contributor
timestamp: May 29, 2011, 11:09:16 pm
content: I have a power supply that i built recently before the lt317 is 8 after the lt317 its 4 any one got any ideas.

author: Unknown
author_rank: Unknown
timestamp: May 29, 2011, 11:15:53 pm
content: Your schematic appears to have disappeared in thin air, so it's somewhat hard to debug. Dropping voltage is exactly what a linear regulator is supposed to do, so depending on what you connected to the adjust pins, this could be within spec.

author: House91320
author_rank: Regular Contributor
timestamp: May 29, 2011, 11:21:06 pm
content: http://www.eleccircuit.com/lm317-lm338-lm350-current-regulator-calculator/its this but the resistor is 1ohm

author: EEVblog
author_rank: Unknown
timestamp: May 29, 2011, 11:34:15 pm
content: Quote from: House91320 on May 29, 2011, 11:21:06 pmThat's a constant current circuit, not a voltage regulator for a power supply.I think you have the wrong circuit.Try:http://www.electronics-lab.com/articles/LM317/Dave.

author: House91320
author_rank: Regular Contributor
timestamp: May 29, 2011, 11:38:13 pm
content: i know i am using another regulator for the variable out put voltage and that works fine. I am using the 317 as the current regulation

author: Bored@Work
author_rank: Super Contributor
timestamp: May 30, 2011, 05:13:09 am
content: Quote from: House91320 on May 29, 2011, 11:38:13 pmAnd we are now supposed to beg you to give us the complete schematic? From my point of view, you either show us the real and full schematics, and you write a useful problem description, or you can stick it where the sun doesn't shine.

author: Simon
author_rank: Unknown
timestamp: May 30, 2011, 07:45:34 am
content: Quote from: BoredAtWork on May 30, 2011, 05:13:09 amhahaha couldn't have put it better myselfHouse: we need to see the full schematic to get an idea of what your up to. My guess is that you have a lower resistance load than the final current regulator can supply current to so there is a massive voltage drop

author: Zero999
author_rank: Super Contributor
timestamp: May 30, 2011, 05:55:23 pm
content: It's not a very good way of doing it. The current limiter circuit drops around 4V just before the current limiting kicks in and the voltage regulator will drop around 2.5V so the input voltage needs to be a whopping 6.5V higher than the output voltage.

author: House91320
author_rank: Regular Contributor
timestamp: May 30, 2011, 07:54:39 pm
content: solved it i had the taps on my power supply wrong
LT3652 Efficient Solar charger. Example schematic from datasheet - weird - Page 1
Forum section: electronics / projects

author: rowifi
author_rank: Contributor
timestamp: January 02, 2024, 12:38:24 pm
content: THE DATA SHEET HAS A SCHEMATIC DIAGRAM FOR : 2A Solar Panel Power Manager With 7.2V LiFePO4 Battery and 17V Peak Power Tracking.The input comes from a solar panel and is specified to be lower than 40V,The battery is 7.2VThere are two diodes in the schematic, one from the battery and another from the solar panel both connected to the LOAD.As I see it the higher voltage will make it to the load, so if the load is requires 7Volt and the solar panel supplies 10v to 40v that higher voltage will likely destroy the load.I can't work out what is the intention for this schematic am I missing something.Thanks

author: Peabody
author_rank: Super Contributor
timestamp: January 02, 2024, 02:41:07 pm
content: It looks like that's right. And the lighter the load is, the more likely it will be toasted. You would need a regulator before the load - either a buck or a buck/boost depending what voltage you need for the load.This circuit also has a diode drop in the battery line. That's not a huge problem in a 2S circuit, but not ideal.

author: magic
author_rank: Super Contributor
timestamp: January 02, 2024, 03:02:02 pm
content: You could omit direct connection to the panel and power the load from the LT's buck converter, but doing so interferes with Li-ion charge termination logic: when battery voltage reaches 4.2V per cell the charger enters CV mode and is supposed to stop charging when battery current drops to 10%, allowing the battery to rest and fall below 4.2V. This may never happen if there is extra load in parallel with the battery.
LT5517 SDR receiver - Page 1
Forum section: electronics / projects

author: ealex
author_rank: Frequent Contributor
timestamp: November 28, 2014, 11:16:47 am
content: HelloI've been playing with a LT5517 based receiver:LT5517 datasheetThe schematic is simple, using the datasheet and and example from "GR1-MANUAL 1021 KTH-SDR WIDEBAND RECEIVER"It works quite well - very sensitive even with a bad antenna ( 3 loops of wire taped on the inside of a window ) , but i's fussy about the LO input signal - a si570 based LO is useless - square wave outputFor now i use a signal generator and ~ -5 dBm for LO over 40 MHz ( a pll based VCO is planned, but next year ). For LO under 40 MHz i need to go to 0 dBm .Also, because of it's huge bandwidth - 40 to 900Mhz it needs very good input filters, otherwise it gets overloaded ( need to build them also )I've attached a picture of the board, the schematics in KiCad and some sample audio files - the final.mp3 one got some air traffic data, processed to remove the silent portions and heavily compressed.The other one is a weak JT65 signal - i think it can be decoded from this file
LT8614 silent switcher part number confusion - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: September 17, 2020, 07:58:38 am
content: I am looking at the datasheet of the LT8614:https://www.analog.com/media/en/technical-documentation/data-sheets/LT8614.pdfThere are two -40/+125C parts, why? I can't see any difference between them.

author: ilqpli
author_rank: Newbie
timestamp: September 17, 2020, 08:46:59 am
content: As i know, both are designed to work within -40/+125C, but "E" was only tested under 0/+85C in QC, but "I" was tested in -40/+125C. (modified the min. tested temperature of e grade)detail can be found in below:https://www.analog.com/media/en/technical-documentation/product-selector-card/2PB_MP.pdf

author: Simon
author_rank: Unknown
timestamp: September 17, 2020, 09:35:55 am
content: I see, thanks, you would have thought that at £10 a chip they would be more honest. I ended up picking the 150C part just to be on the safe side as clearly that is tested.

author: mikerj
author_rank: Super Contributor
timestamp: September 17, 2020, 12:26:25 pm
content: The datasheet does explain this quite clearly, I don't see how they are being dishonest?Operating Junction Temperature Range (Note 2)LT8614E............................................. –40°C to 125°CLT8614I.............................................. –40°C to 125°CLT8614H ............................................ –40°C to 150°CNote 2: The LT8614E is guaranteed to meet performance specificationsfrom 0°C to 125°C junction temperature. Specifications over the –40°Cto 125°C operating junction temperature range are assured by design,characterization, and correlation with statistical process controls. TheLT8614I is guaranteed over the full –40°C to 125°C operating junctiontemperature range. The LT8614H is guaranteed to meet performancespecifications from –40°C to 150°C operating junction temperature range.

author: Simon
author_rank: Unknown
timestamp: September 17, 2020, 01:26:23 pm
content: Yes I missed that bit but it's double dutch and intentionally written to be ambiguous in fact it's still not clear. All they have to say is this part is tested, this other part is not but we believe it will work. I mean screw me, people bitch about AVR specs yet they write it much more plainly than that.
Ltc 1250 differential thermocuple circuit analysis and questions - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: February 11, 2024, 10:36:04 pm
content: I'm trying to understand this thermocouple circuit made with ltc 1250. As far as I understand, the output should be 10mV/C, but there was an error in the datasheet its writed (100mV/C).A difference amplifier was designed for the K type thermometer, assuming the Seebeck effect was 40uV per C degree. The gain of this difference amplifier was set as 250, so we can obtain 10mV at 1 degree change. I understand so far.The other thing is the connection of LTC1025. LTC 1025 is set as the reference point of the 3k resistor. Adding a voltage reference to this point in the difference amplifiers creates a constant dc bias at the output and it is not multiplied by the gain. The voltage coming from the LTC1025 thus adds 10mV/C offset to the output.What I don't understand here is the connection of LTC1025 to the negative power supply with 33k. I think the LTC1025 will be 0 C when measuring (-) degrees lower than 0. And it will switch to sinking mode. However, in order not to create an offset while sinking, the more negative V-supply is connected as the sinking source. Is this true?My other question is what is the purpose of capacitors C1 and C2?Another question is how were Resistance values determined when multiplying by 250 times? I think it was calculated from the noninverting and inverting gain coefficients, but I couldn't understand the exact purpose of 5k.Another question is, did we also apply the offset voltage (ltc1025 Vout value) that we applied to the 3k resistor as a reference to the input of the 5k resistor?http://tinyurl.com/2bgv3x6dFalstad circuithttp://tinyurl.com/28ntbojuI think it's a kind of trimming circuit.(Not sure) I saw a trimming circuit like the one in the photo I added, but this one looked interesting. Is there a source explaining a similar trimming circuit?Thanks for your answers.

author: moffy
author_rank: Super Contributor
timestamp: February 11, 2024, 11:39:12 pm
content: Some answers:1. R9 is only necessary if the LT1025 has to sink current for temperatures below 0C.2. The LT1025 adds to the +ve input: (10mV/C)*R2/(R4 + R5)3. C1 is for stability of the opamp
ltc app note directory - Page 1
Forum section: electronics / projects

author: CopperCone
author_rank: Super Contributor
timestamp: May 22, 2018, 06:49:28 pm
content: Is it available on the Analog devices website? I can't find a web page with all the link s to the individual PDF. It's rather annoying.You can go tohttp://www.analog.com/media/en/technical-documentation/application-notes/anbut then you need to fill in the PDF file name, so its a pain in the balls.Does anyone have a text file of the notes at least? So I can painstakinly download everything. Figures AD does not give a shit, they always felt super corporate to me.

author: GerryBags
author_rank: Frequent Contributor
timestamp: May 22, 2018, 07:05:37 pm
content: Yes, it's changed pretty recently. The linear.com address from my history redirected to the new site. I did get to this:http://www.analog.com/en/design-center/search.html?q=application%20noteAny use? The linear and ADI notes are all together, there are 1348

author: CopperCone
author_rank: Super Contributor
timestamp: May 22, 2018, 07:09:41 pm
content: Man you would need to wire yourself to an expresso machine to process that. LTI had it nicely on their webpage.It might just be faster to go on the way back when machine and get the specific file names. I was really used to using the LT one to find stuff.This is what I think:

author: GerryBags
author_rank: Frequent Contributor
timestamp: May 22, 2018, 07:13:26 pm
content: Linear's app notes have beenassimilated!
LTC1046CN8 or ICL7660 - Page 1
Forum section: electronics / projects

author: Andbro
author_rank: Regular Contributor
timestamp: October 21, 2019, 07:10:40 pm
content: Hi,Which one do you recommend as a regulator between the LTC1046 and the ICL7660?If I want to put a tantalum capacitor at the input and output, does the ESR value is important ?Thank

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 21, 2019, 07:22:51 pm
content: It would pretty much depend on how much current you're going to draw from the output.The LT1046 has a significantly lower output resistance, meaning you can draw more current for a given voltage drop. OTOH, it has higher supply current and a slightly lower efficiency.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 21, 2019, 08:03:27 pm
content: The capacitor ESR can matter, as these switched capacitor converters can produce quite some current peaks, especially the lower resistance LTC1046. Filtering can work better with low ESR caps - though some ESR helps to avoid possible resonances if there are more caps in parallel.

author: mariush
author_rank: Super Contributor
timestamp: October 21, 2019, 09:04:42 pm
content: The LT would be better, but it depends on your needs, if you really need the current the IC can supply.There's also other pin compatible chips out there, and clones of 7660 ...Here's over 300 charge pump inverter chips, which can convert 5v to -5v... if you need higher voltages filter further to see only chips that can do more than your input voltage :https://www.digikey.com/short/pd8qp8Some may not have the same pinout so double check, but all can do 25ma or more. The surface mount ones could in theory be installed on some DIP adapters if needed.
LTC1052 TLC2652 - Page 1
Forum section: electronics / projects

author: R_G_B_
author_rank: Frequent Contributor
timestamp: October 03, 2014, 06:49:15 pm
content: Are these two Devices the same the reason I ask is that Texas instruments off both types of IC with the same package and pin out?If they are not the same device overall which of these Devices has the better performance.R_G_B

author: bobcat
author_rank: Regular Contributor
timestamp: October 03, 2014, 07:06:20 pm
content: The best way to determine is to compare the data sheet specs. Also check to see if either are EOL and one replaces the other for new designs.
?: LTC2400 with buffer, troubles, need help - Page 1
Forum section: electronics / projects

author: GigaJoe
author_rank: Frequent Contributor
timestamp: January 23, 2018, 03:06:14 am
content: Hello, everyoneUPD: opamp faulty, seems Chinese fake ...( replace it , and all !!!! )need some help in understanding:U2 - LTC2400 , NOT 74LTC2400 (U2) + buffer (U1) , input shorted. LTC Vref- 5.0000V , Vsup- 4.95VResult:if U2 input disconnected , U1 output grounded over 1M resistor the output 2mkVremoving resistor and connecting input LTC2400 (U2) - R4, C3 - around 2.5V slowly discharging over voltmeter resistance.shorting capacitor by 100K resistor, output very low , and i'm getting triangle impulses around 200 mV p-p.LTC2400 digital output hang in the air.?: Where is my mistake ....? What else for debugging ?or it opamp faulty ?

author: Kleinstein
author_rank: Super Contributor
timestamp: January 23, 2018, 01:01:13 pm
content: The diodes for input protection are a little odd. The negative sid would allow up to -8 V and this too much for the LTC2400. This diode could go towards GND.The positive side diode is only towards a divider, so with more current from the input the voltage could rise well over the set 4 V. The should be more like a lower impedance sink. So maby a divider to 3 V plus an PNP transistor to amplify the current.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: January 23, 2018, 10:38:28 pm
content: D2 - are correct in my real schematics , grounded to the neutral.I'm not 100% certain about input diode protection , it just a prototype , to hook arduino over ADUM isolation. So i have 2 independent transformers to run , for digital and analog parts , then debugging the code to get a data , them see any improvements , analog parts again , pcb construction etc ... that a plan for now ...thinking, for a next cycle need a different model of LTC24XXX , with differential input and differential Vref,
LTC2928: what is the trick to allow *four negative* voltage monitoring? - Page 1
Forum section: electronics / projects

author: F1GWR
author_rank: Regular Contributor
timestamp: August 14, 2024, 08:56:54 am
content: Hi,I saw an example of one LTC2928 (among three) used in the Agilent DSO9404A tomonitor four negative voltages. Schematic is not available.The question is not "would this be possible?", because it is, but "which application circuit using this LTC2928 would be able to monitorfour negativevoltages?" As this IC was initially designed solely forfour positiveorone negative and three positivedepending on the VSEL tying.Checked datasheet, app notes and design notes but didn't find any clue...Any help appreciated.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: August 14, 2024, 11:26:37 am
content: look to the left: OP484, likely 3 of the four channels of it do it.

author: F1GWR
author_rank: Regular Contributor
timestamp: August 21, 2024, 08:25:42 am
content: Quote from: Andree Henkel on August 14, 2024, 11:26:37 amHi Andree,Thanks. Sorry for late answer, just saw your message.Yeah you may be right obviously! This fourfold opamp should be wired as an inverting amplifier with gain -1. I'll check that when I will have some time after urgent tasks...Will let you know.Christian
LTC3130-1 reverse current - Page 1
Forum section: electronics / projects

author: kuon
author_rank: Regular Contributor
timestamp: November 01, 2019, 08:50:31 pm
content: I am using a LTC3130-1 in one of my project, and I power an nRF52840 with it.In the doc of the nRF52840 there is this part:QuoteI'd like to keep high efficiency (that's why I use the LTC3130-1), and I was wondering if I needed a protection. I have an LTC4162-F behind the LTC3130-1 which handle the battery charging.Do you have any recommendations?
LTC3588 energy harvesting regulator - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: April 19, 2014, 06:36:03 pm
content: Consider the attached schematic.It does work, but after prolonged operation it occasionally, intermittently, kills its LTC3588s.Any idea why the chips are dying sometimes? And how can this failure be prevented?Overvoltage from the pizeoelectric transducer is a possibility, but the chip is supposed to have protective internal clamps to protect against this.The only goal of the circuit is to light up a LED, powered by mechanical energy harvesting. A large output capacitor is used, along with a very high brightness, high efficiency LED and a very small current through the LED, in order to allow the capacitor to carry the load during occasional intermittency in the mechanical excitation, and allow the LED to smoothly carry on shining for a couple of seconds without the capacitor being discharged too fast.

author: David Hess
author_rank: Super Contributor
timestamp: April 20, 2014, 07:34:35 pm
content: The first thing that comes to mind is a common mode voltage spike, maybe caused by ESD, between the cantilever and the LTC3588 ground. This could also enter from the LED side.
Ltc3780 - Page 1
Forum section: electronics / projects

author: GOD
author_rank: Contributor
timestamp: April 25, 2020, 06:04:51 pm
content: Hello guys as a fellow newbie how do I set the current limit on this buck converter? Planning to build a power supply with it but cant figure out how to set current limit

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 25, 2020, 06:23:51 pm
content: Quote from: GOD on April 25, 2020, 06:04:51 pmHi,read page 17 of the datasheet:RSENSE Selection and Maximum Output CurrentRSENSE is chosen based on the required output current.The current comparator threshold sets the peak of theinductor current in boost mode and the maximum inductorvalley current in buck mode. ….This is a buck-boost controller. Not really a good candidate for a newbie ...Regards,Jay_Diddy_B

author: GOD
author_rank: Contributor
timestamp: April 26, 2020, 04:19:14 pm
content: Quote from: Jay_Diddy_B on April 25, 2020, 06:23:51 pmwhat would recommend for power supply with current liming
LTC3803 - DC649A Evaluation / development kit, change of transformer - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: January 16, 2021, 03:30:03 pm
content: LTC3803 - DC649A Evaluation / development kitI'd like to adapt this isolated design to run at 12V input. I only need about 2W for tests. (In fact, ideally I'd like to adapt the dev board to deliver 12V output at 100mA or so).I can adjust feedback resistors but the flyback transformer is still a problem. I think about 20uH to 70uH will be OK given my load requirements and the 200kHz, 6.5 to 80% duty.(a) I can't see it anywhere on the PCB layout shown on the PDF (https://www.analog.com/media/en/dsp-documentation/evaluation-kit-manuals/dc649A.pdf)(b) I'm happy to bodge-in a replacement, I am wondering if this will doBourns SRF1260-470M (http://www.farnell.com/datasheets/2178764.pdf)Interestingly, LT put the output windings in parallel - I assume this works due to close voltage matching, the "slack" ending up heating the coils?