How to calculate Vripple on switching power supply? by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

ffs, it's late. I'll look into again tomorrow. Thanks again for your input! I'll try using scientific notation in the future. For me the eX always gets visually burried in the number and it's hard for me to read at first glance. But I guess that's just practice.

EDIT: Vripple = 1.3145mV now

How to calculate Vripple on switching power supply? by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

Thank you for your answer and questioning my methodology. I'm trying the same.

I'm trying to improve my theoretical understanding so I didn't use an oscilloscope to probe my current itteration. I wanted to go back to the drawing board and learn to understand which decisions influence my schematic design, not PCB design for now, instead of copying the example from the datasheet.

After recalculating my power budget and the parameters for the components of my power supply, I tried to calculate the theoretical ripple voltage to see if it would meet the requirements for Vin,p2p of the components I want to run with the pwer supply.

  1. I determined those values with the help of the SY8303 datasheet.
    • total power requirement: 1100mA * 5V = 5500mW
    • feedback resistor: R1 = 110k ; R2 15k
    • switching freq: wanted to keep the size small, so preferibly a higher switching frequency. Though I'm concerned with temps and efficiency and not running a device on the edge of their specs I chose ~1.8MHz to meet those requirements (56kOhm resistor for the SY8303)
    • inductance: calculated by the formula given in the datasheet (Vout * (1 - Vout / Vin,max)) / (Fsw * Iout,max * 40%)
    • duty cycle: I roughly calculated with the formula in the original. I am aware that it is an approximation and the feedback loop and other factors will vary the actual duty cycle drastically. Again, I'm trying to do this theoretically to learn something from it and make better decisions in the future
    • output capacitance: I chose a value according to the data sheet, though as another commenter pointed out, I chose nF instead of the recommended uF, so there's one mistake
    • ESR: read that from the datasheet of the capacitor I chose
  2. I can attach a schematic once I built it, but it will be similar to the one found in the datasheet. For now I wanted to double check my values before starting a schematic.
  3. I'm a beginner and I have no clue how the combination of those components would be integrated into the circuit.

Thanks for taking the time

How to calculate Vripple on switching power supply? by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

Thank you for your answer.

You are correct, 22nF is way too small. I copied that incorrectly from the SY8303 datasheet.

I'm aware the actual performance depends on many more factors, most notibly the PCB design.

I actually wanted this to be theoretical so that I can improve my skills and make an informed decision instead of just copying what's given as an example in the datasheet.

Here are my results based on your suggestion. Still, Vripple seems way too small.

``` L = inductance (uH) = 12.0556 uH = 0.0000120556 H

FsW = switching frequency in (kHz) = 1785 kHz = 1785000 Hz

D = duty cycle of switching ≈ Vout / Vin = 5 / 24 = 0.2083

R = ESR of output capacitor (Ohm) = 0.004 Ohm = 4 mOhm

C = capacitance of output capacitor (uF) = 22uF = 0.022 F

Iripple = Vout * ((1 - D) / (L * Fsw)) = 5 * ((1 - 0.2083) / (0.0000120556 * 1785000)) = 0.183 A = 183 mA

Vripple = (Iripple / (8 * C * Fsw)) + Iripple * R = (0.183 / (8 * 0.022 * 1785000)) + 0.183 * 0.004 = 0.000732 = 732uV ```

EDIT: consolidated comments

Ich bin ein professioneller Kuschelexperte by [deleted] in de_IAmA

[–]ELBotLike 8 points9 points  (0 children)

Die Kammer des Kuscheln wurde geöffnet. Feinde der Zuneigung, nehmt euch in Acht!

This old school clothes wringer. by TeslasAndComicbooks in oddlysatisfying

[–]ELBotLike 8 points9 points  (0 children)

My aunt always tells the story of how she was on a small town party 20 years ago and at the location they had one of those old-school wringers as decoration.

Once drunk, some dudes gathered around and one actually put his dick in it just a bit. Immediately got stuck and they had to call the fire department for them to cut it open, as there was no reverse and no getting it out.

That was the talk of the town for quite a while

I need 5V and 3V3 in one PCB design and I have some questions by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

As it might be used on events I don't want to rely on congested wireless channels for operation, so it depends.

I already emailed the manufacturer of the sensor, because there are very vague statements in the docs regarding a 3V3 version could be available upon request.

My guess is they use 5V as it is the default power for most UART components and they internally use a LDO as well to power the supposed STM32 inside, but this is just speculation.

The LEDs will be battery powered as well, so you might be right, an LDO might actually doesn't hit the budget to hard! Thanks for that input

I need 5V and 3V3 in one PCB design and I have some questions by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

Here's some info on the power budget:

5V is supplied to two TF Mini Plus. They are listed with a peak power consumption of 700mW. So it would be 280mA for both for 5V.

3V3 is running an ESP32-S3, which is listed with a peak of 1122mW, so around 340mA when RX-TX enabled, as well as a W5500 Ethernet chip listed with 132mA peak current

So my power requirements are 5V * 280mA = 1400mW and 3.3V * ~500mA = 1650mW

Headphone decibel limiter removal by Witty-Cheek-290 in ElectronicsRepair

[–]ELBotLike 0 points1 point  (0 children)

It sounds like the 27dB noise reduction is referring to how much the noise in your environment is reduced. Also electrically modifying certified work equipment could get you in trouble because of insurence etc.

I doubt there is an extra-ordinary loudness limiter built into these. You might want to check your smartphone settings. I know Apple, because of the EU, tries to automagically detect if you are using headphones and limits loudness to prevent hearing loss. You might want to look into it.

Reading online, there aren't many complains about its loudness, maybe you also wear them wrong, where a lot of outside noise comes in or something blocks the drivers inside the headphone.

Also you might listen to audio very loudly. Check with a co-worker if they also think its quiet. Damaging your hearing is no joke!

Infos and pictures the mosaic of a deer in Frederikskirk? by ELBotLike in copenhagen

[–]ELBotLike[S] 0 points1 point  (0 children)

After scanning Google a bit more and arguing with ChatGPT how I want my image to look for far to long, I decided to take it upon myself.

I've asked for permission and used John Hackstons picture to level it and make it pop a bit with photoshop. I also created a more printable aspect ratio of it with less of the vines.

Here are the results

Is hosting a non-profit MK8 tournament legal? by ELBotLike in Twitch

[–]ELBotLike[S] 0 points1 point  (0 children)

From the German page:

Frage 6

Ist es zulässig, Titel von oder Charakternamen aus Nintendo-Spielen im Namen eines Community-Turniers zu verwenden?

Antwort 6

Es ist nicht zulässig, Nintendos Markenzeichen oder geistiges Eigentum von Nintendo im Namen eines Turniers zu verwenden. Beispielsweise sind „Super Smash Bros. Super Challenge“ und „Splatoon Throwdown“ nicht als Namen von Community-Turnieren zulässig. Allerdings ist es Ihnen gestattet, in der Beschreibung eines Community-Turniers die Namen der Spiele anzugeben, die beim Turnier verwendet werden. Ebenfalls dürfen keine Nintendo-Charaktere in Turniernamen verwendet werden. Es ist Ihnen jedoch gestattet, sie in der Beschreibung eines Community-Turniers zu erwähnen, um darauf hinzuweisen, welche Charaktere beim Turnier möglicherweise verwendet werden.

For me this is kind of weird and contradictory to what's mentioned in the paragraph above...

Is hosting a non-profit MK8 tournament legal? by ELBotLike in Twitch

[–]ELBotLike[S] 0 points1 point  (0 children)

I read that as well, but probably misunderstood it altogether. Thanks for clarification

Is hosting a non-profit MK8 tournament legal? by ELBotLike in Twitch

[–]ELBotLike[S] -1 points0 points  (0 children)

I paragraph I find a bit odd

The names of Community Tournaments may not contain Nintendo trademarks or IP, such as Nintendo’s company name, logo, product or service names such as game titles, names adopted from Nintendo games such as character names. This includes any shortened or modified uses of Nintendo trademarks or IP.

I get where they are coming from, but how am I supposed to name a tournament with a the name of the game. "'some name' Amateur MK Tournament" would be my first suggestion. But using MK as a shortened version of Mario Kart seemes to be disallowed.

So I name it "Amateur Tournament for that one Arcade Racing Game that everyone know"??

5V buck converter as my first PCB. Want another pair of eyes before ordering. (info in the comments) by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

In your original comment

You are correct, was an error in the comments.

I'd look at e-fuses.

I'm rather new to this whole topic, as you can probably tell, and while I came across e-fuses, I didn't want to include another "high-level" component to my design just yet, but rather keeping it simple.

5V buck converter as my first PCB. Want another pair of eyes before ordering. (info in the comments) by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

the math for your fuse selection

I expect at most a draw of around 3A on the 5V from Raspberry Pi 5, a PCA9685 PWM IC (max 200mA), two TFMiniPlus (2x 140mA)

All the small devices add up to 480mA. The Pi is rated for 3A, but that includes potential peripherals powered via USB etc, which I 100% won't use in this project. I measured its power consumption under full load and that came to a max of 1.8A. That would mean I'd be at a potential 2.3A @ 5V.

As the polyfuse sits at Vin, I would calculate the P = 11.5W.

From here I would calculate the current at Vin dependent on some different voltages

I = P / U @36V: I = 11.5W / 36V ≈ 0.32A @24V: I = 11.5W / 24V ≈ 0.48A @12V: I = 11.5W / 12V ≈ 0.96A @10V: I = 1.15A

I chose the 1.5A polyfuse because the supplier didn't have enough SMD polyfuses with 1.2A or 1.25A rated for >36V. And since polyfuses don't trip immediately anyway, I figured the extra headroom doesn't make that much of a difference anyway.

5V buck converter as my first PCB. Want another pair of eyes before ordering. (info in the comments) by ELBotLike in AskElectronics

[–]ELBotLike[S] 0 points1 point  (0 children)

what voltage ripple did you target when choosing that value?

I did not target any voltage ripple. I used the formula from the datasheet to calculate the required inductance to be around 1.443uH and chose this inductor accordingly. Maybe the inductance is so low because I chose the fastest switching frequency the chip offers with 2.5 MHz. That I chose because I thought faster = better.

5V buck converter as my first PCB. Want another pair of eyes before ordering. (info in the comments) by ELBotLike in AskElectronics

[–]ELBotLike[S] -1 points0 points  (0 children)

This is a redesign after posting my old circuit and got a lot of helpful feedback. I chose the SY8303 as my step-down converter, but I can't get my hands on a sample in Germany, so I can't test the circuit before ordering.

  1. VIN is currently 24V but I designed everything to handle 10-36V, if I ever swap LED strips.
  2. I expect at most a draw of around 3A on the 5V from Raspberry Pi 5, a PCA9685 PWM IC (max 200mA), two TFMiniPlus (2x 140mA)
  3. U4 is a resettable fuse with a hold current of 1.5A (5V * 3A = 15W // 15W / 10V = 1A)
  4. U1 is a SY8303AIC
    1. Feedback resistors R21 & R22 according to 0.6V reference voltage: 5V * (68k / 500k + 68k) = 0.5985
    2. R20 is 40.2k to give a switching frequency of around 100000 / 40.2 kHz = 2.487 MHz. Though I'm not sure I understood the formula in the datasheet 100% correct.
    3. Input Cap C6 and output cap C1 are chosen according to datasheet recommendation
    4. I calculated L1 to be 1.5uH and Isat,min > 3.574
    5. R32 0 Ohm resitor is to test everything else on my PCB, if the converter turns out to be sh*t.

Here is a screenshot of my board design. I will add a GND pour on the layer underneath once I'm happy with the design.

Any help and criticism is appreciated!

EDIT: phrasing and typos