Please review my ESP based WLED controller board for WS2815 12V LED Strips - New - Page 1
Forum section: electronics / general

author: ElecGeek
author_rank: Contributor
timestamp: June 30, 2025, 12:21:57 am
content: I'm designing an ESP-based WLED controller board for WS2815 12V LED strips, with a primary focus on energy efficiency.To minimize power consumption, my goal is to completely shut down the system when the LED strip is turned off.However, the current buck converter powering the ESP module draws about 8 watts even when the LEDs are idle, making it unsuitable for low-power operation.I am using below components:Buck Converter: TPS562201 (12V → 5V regulated)Microcontroller: XIAO ESP32-C3 (with built-in USB-C)LED Strip: WS2815 (12V digital LED strip)Switching MOSFET: Logic-level N-MOSFET (IRLZ44N)Level Shifter: BSS138 MOSFET-based (3.3V to 5V data line)Status LED: Green LEDI've attached the schematic—could you please review it and let me know if I've missed anything or if there are areas for improvement?I designed it with limited experience, so I’d really appreciate your feedback on whether the setup is correct and functional.Thanks

author: PlainName
author_rank: Super Contributor
timestamp: July 01, 2025, 01:12:28 pm
content: Just a note about the schematic...Usually, power is up and ground is down. Your chips have power down and ground up. The ground wire above the buck converter is confusing. You would do better to reorientate or redraw the chip symbols so you connect power to the top of them and have ground come out low down.Also, concerning ground, usually the ground symbol is used wherever a connection is required (within reason). That would remove quite a lot of confusing wire in your schematic and make the design clearer. (But don't conflate this with saying you should use net labels instead of wires - no, ground (and power) is a special case.)Connectors... one has pin1 for power a t'other has pin1 for ground. Scope for seriously screwing up there. It's a personal thing but generally I always make pin1 ground (on the basis that ground is always connected, and there will always be a pin1). Then, logically, power will be at the other end.Also on connectors, it would help if you label what the pin function is. Not net labels per se, just what it is (+5V, 0V, data) so one doesn't have to check where connections go to figure out what they are.

author: ElecGeek
author_rank: Contributor
timestamp: July 06, 2025, 07:06:39 am
content: Thanks for the suggestions. I have re-wired everything and made some improvements. Please have a look and review once.I have one query, the R2 for buck convertor was connected to AGND, I have connected it to Ground, I did right?Also can you please let me know what would be the best way to extend it, so that it can be used with a 5V strip as well?

author: PlainName
author_rank: Super Contributor
timestamp: July 06, 2025, 09:24:52 am
content: While not perfect it's much better to figure out what's going onBut it ain't going to work. An obvious issue is U7, the dual-supply bus transceiver. According to the schematic, the intention seems to be to have U7 interface between signal levels on the ESP32 and the LED string fed from U8. In fact, U7 is taking it's voltage source from the U8 data signal, so nothing will happen. Instead, U7.8 (VCCB) should connect to whatever voltage the LED string needs for data (presumably +5V) and R8 connect to U7.7 (1B).The DIR pin (U7.5) is superfluous for your purposes since data will only go one way: towards the LED string. Connect it to either VCCA or VCCB to keep it pulled how, so data always goes A->B. Then D4 on the ESP32 is your data pin and should connect to U7.2.I am failing to understand the intention for Q1.Anyyay, as to your query about R2: there is no AGND. Is that something you saw on the datasheet and figured it means GND? In this case that would likely be correct.

author: ElecGeek
author_rank: Contributor
timestamp: July 06, 2025, 11:23:36 pm
content: My bad, my understanding was wrong for level shifter I used here. Corrected it out.Intention of Q1 is to save energy when LED strip is off. So I added N-Channel Mosfet to turn of completely. Am I doing it correctly here?For R2, I see it in datasheet. Please have a look.Updated Schematic:

author: tooki
author_rank: Super Contributor
timestamp: July 07, 2025, 07:39:01 am
content: Quote from: ElecGeek on July 06, 2025, 11:23:36 pmThe TPS62203 datasheet is pretty bad (including the totally stupid symbol with the pins in physical order). Take a look at the documentation for the part’s evaluation board; it has a real-world schematic.

author: PlainName
author_rank: Super Contributor
timestamp: July 07, 2025, 08:45:06 am
content: QuoteThat's a low-side switch of ground, which could lead to tears. Take ground out and the 12V may be fed back down the data line into the shifter. Further, if there is any ground around the LED string there's a chance that the still live 12V could short to it.It would be much better to switch the supply, i.e. 12V.However, on checking theWS8215 datasheetit seems that the quiescent current is max 1uA per LED, which is not a lot even if you have a few of them in the string. Of course, a wall panel pretending to be a TV would be a different matter, but then your circuit wouldn't be able to drive even a small corner of thatAlso, the minimum high level input (VIH) is 0.7VDD. For a 12V supply that would be 8.4V, so your 5V shifter likely won't provide sufficient voltage to drive the data line.

author: ElecGeek
author_rank: Contributor
timestamp: July 07, 2025, 09:41:25 am
content: I think there is some confusion with WS2815. Please refer to below link. I think 5V data line would work. Mine is WS2815B.https://github.com/stanleyondrus/LedBoxV2/issues/1Also, you are suggesting to use P-Channel Mosfet to switch 12V instead of 0V Neutral, which is what I am doing right now?

author: PlainName
author_rank: Super Contributor
timestamp: July 07, 2025, 09:57:21 am
content: OK. The datasheets for these things can be suboptimalIt would be normal to use high-side switching for something like this. P-channel MOSFET would be appropriate.

author: ElecGeek
author_rank: Contributor
timestamp: July 07, 2025, 09:47:24 pm
content: Thanks for your suggestions. Please find the updated schematic below. Is everything fine now? Any other suggestions/improvements?Adding PCB as well. Can you please also review it and give me feedback.

author: PlainName
author_rank: Super Contributor
timestamp: July 07, 2025, 10:40:52 pm
content: Two things:1. Please use the forum's tools for attaching images. That way they don't get in the way until one wishes to look at them, and when they do pop up they fit the window. Yours don't fit my window (too big), and I don't want to look at both at the same time not have to sideways scroll to see them.2. The PMOS needs a pullup. Do a google for how to drive them, or check this link as a for instance:https://electronics.stackexchange.com/questions/595465/can-you-drive-a-p-mosfet-as-a-high-side-switch-directly-from-a-microcontroller

author: ElecGeek
author_rank: Contributor
timestamp: July 08, 2025, 05:03:55 am
content: Here you go. Updated it. Hope everything is fine now. Please provide feedback.

author: floobydust
author_rank: Super Contributor
timestamp: July 08, 2025, 05:31:20 am
content: How does it start up? You need U1 EN +ve to turn it on, yet the ESP32 is powered from that 5V reg - which is off.Fuse comes first. D2 should be after the fuse.

author: ElecGeek
author_rank: Contributor
timestamp: July 08, 2025, 03:00:08 pm
content: That is true, I will remove EN altogether as it will not waste too much power. But if I want to drive buck convertor what would be the best way to turn it off completely?Also is there a way in Easy EDA to run this circuit in simulation, so that I can avoid these type of mistakes?

author: floobydust
author_rank: Super Contributor
timestamp: July 11, 2025, 03:14:30 am
content: I don't see a need to turn off the buck-converterThe WS2815's will draw a lot of quiescent current.At some point, electronics with modules can be too much for a simulator. I don't know Easy EDA.Most of us build a prototype to see if it's going to work. Or ask for a review here like you have done, to spot bigger issues.

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 01:18:33 pm
content: Quote from: PlainName on July 07, 2025, 08:45:06 amThat’s some outdated third-party version of the datasheet. The current datasheet on Worldsemi’s own webpage, attached below to save everyone from having to fill out a form to get to the downloads, is crystal clear on the voltages:Absolute maximum ratings:Power supply voltage VDD: 9.5V … 13.5VLogical input voltage VI: -0.5V … 5.7VElectrical characteristics (for VDD= 12V):VIH: 2.7V … 5.7VVIL: -0.3V … 1.5V

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 01:25:44 pm
content: Quote from: floobydust on July 11, 2025, 03:14:30 amDatasheet says 1 μA, so probably not a concern until into the hundreds of LEDs?

author: PlainName
author_rank: Super Contributor
timestamp: July 11, 2025, 01:45:27 pm
content: QuoteEr, this was resolved and corrected up-thread. Is there some reason you need to pick over it again several days later?(At least I provided a link the one I used, to be helpful.)

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 02:50:39 pm
content: Quote from: PlainName on July 11, 2025, 01:45:27 pmHuh? Where? The GitHub page linked earlier has screenshots with the same incorrect values.Quote from: PlainName on July 11, 2025, 01:45:27 pmBecause I was scrolling through myUpdated Topicslist and it showed up? And it didn’t look like the voltage question had been conclusively answered?Quote from: PlainName on July 11, 2025, 01:45:27 pmHuh? So did I, I attached the PDF, since I can’t be sure if a link would even work, since it required filling out a form to download it.Stating the unequivocal values is also helpful to anyone who stumbles upon this thread in the future (for example, from a web search on the topic).

author: PlainName
author_rank: Super Contributor
timestamp: July 11, 2025, 03:57:50 pm
content: QuoteIt shows the erroneous one and then the correct one (for the B).QuoteSorry, I missed that. Too used to checking in-text links, I guess

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 06:19:31 pm
content: Quote from: PlainName on July 11, 2025, 03:57:50 pmI even said “attached below” in the text!Quote from: PlainName on July 11, 2025, 03:57:50 pmAnd just as you overlooked my attachment, I overlooked the last screenshot in the GitHub thread!!However, the thread does not include the voltage logic thresholds table at all, and the last screenshot there does not agree with thecurrentdatasheet (the one I attached).

author: floobydust
author_rank: Super Contributor
timestamp: July 11, 2025, 06:19:53 pm
content: Quote from: tooki on July 11, 2025, 01:25:44 pmWhat I've seen on the datasheets, Input Current is +/-1uA (I take to mean DIN) but quiescent current (all LEDs off) is 2.1mA or say 210mA for a string of 100 LED's.I think you would use a switch to disconnect power from them, if OP's board is battery powered. It's high parasite drain compared to the buck-converter.There are also variants WS2815B, C.

author: tooki
author_rank: Super Contributor
timestamp: July 11, 2025, 06:23:59 pm
content: Quote from: floobydust on July 11, 2025, 06:19:53 pmOh, I think you’re right about the input current meaning the data pin. But in that case I don’t see quiescent current anywhere on the datasheet.

author: floobydust
author_rank: Super Contributor
timestamp: July 11, 2025, 06:45:22 pm
content: It's kind of a mess with theWorldsemi Co.datasheets. Even timing, LED current has moved around.WS2815B-V1_V2.2seems to be the latest and says "Quiescent Current＜2mA".OlderWS2815 V1.1gives 2.1mAWS2815B-V1"added power consumption" at V2.1 {which appears to be the datasheet version}

author: tooki
author_rank: Super Contributor
timestamp: July 12, 2025, 09:20:35 am
content: Quote from: floobydust on July 11, 2025, 06:45:22 pmOk, I finally did a text search in the datasheet for “quiescent” and found it as a header in the table of the LED emitter characteristics (where the light output and wavelengths are listed)… wtf? (I mean, what is the “quiescent current” of an LED? Not the control chip, but the LED itself…)

author: ElecGeek
author_rank: Contributor
timestamp: July 15, 2025, 08:04:04 am
content: Based on the suggestions, I have made some changes in the schematic. Can you guys please review it. Am I missing anything here?

author: tooki
author_rank: Super Contributor
timestamp: July 15, 2025, 10:03:38 am
content: You know, you could probably save a bit of power by dispensing with the level shifter altogether and using a 12V->3.3V buck converter so you’re not burning off 5V->3.3V in the LDO on the MCU board.The ESP32-C3 datasheet specifies a minimum logic high output as 0.8xVdd, which works out to 2.64V. That’s awfully close to the 2.7V specified in the WS2815B datasheet. Given that in practice, the MCU is practically guaranteed to output close to 3.3V as a high, it would likely just work. But if you wanted to be on the safe side, you could use an adjustable buck converter and set it to 3.4V, which is still well within the MCU’s 3.6V absolute limit, and which would guarantee a logic high output of 2.72V.

author: ledtester
author_rank: Super Contributor
timestamp: July 15, 2025, 12:17:59 pm
content: Quote from: ElecGeek on July 15, 2025, 08:04:04 amThe EN pin of the TPS562203 needs to be at least 1.2V in order to turn the switcher on.See sections 5.5 and 6.3.6 of the datasheet:https://www.ti.com/lit/ds/symlink/tps562203.pdfThere also seems something amiss with your +12/VCC high-side switch... R7 should be connected to +12V instead of VCC. And it would help if you flipped Q1 so that +12V was on top.And in your PIN OUT section is "+12V" connected to "VCC" or is it just a comment/label and not a net name?

author: PlainName
author_rank: Super Contributor
timestamp: July 15, 2025, 01:03:40 pm
content: Quote from: ElecGeek on July 15, 2025, 08:04:04 amPlease don't succumb to using labels instead of wires. Looks pretty but is less usable than your original.

author: ElecGeek
author_rank: Contributor
timestamp: July 15, 2025, 07:02:50 pm
content: Quote from: tooki on July 15, 2025, 10:03:38 amMakes sense actually, minimum is 2.7V in the WS2815B datasheet. In my current setup it is working without level shifter. I would like to decrease the complexity as much as I can. So shall I just remove level shifter altogether?WLED project suggests to add level shifter though.Quote from: ledtester on July 15, 2025, 12:17:59 pmThanks for pointing out. Still learning.Updated the schematic.Quote from: PlainName on July 15, 2025, 01:03:40 pmPoint noted.

author: ledtester
author_rank: Super Contributor
timestamp: July 15, 2025, 07:23:08 pm
content: If you read the datasheet for the buck converter you'll see that they recommend a 100k pull-up from Vin (+12V in this case) to the EN pin.R7 should go from +12V to the gate of the P-MOSFET. You also need a wire from +12V to the P-MOSFET source.If you flip the P-MOSFET symbol you will avoid the wire crossing in the schematic and it will look more conventional.

author: ElecGeek
author_rank: Contributor
timestamp: July 15, 2025, 11:05:41 pm
content: Quote from: ledtester on July 15, 2025, 07:23:08 pmUpdated the schematic. Thanks for pointing out. I misread the value. I still need to add 15KOHM to ground as well, right?Any suggestion for omitting level shifter altogether here?

author: ledtester
author_rank: Super Contributor
timestamp: July 16, 2025, 12:58:22 am
content: Quote from: ElecGeek on July 15, 2025, 11:05:41 pmNo. Section 6.3.6 says you only need the 100k resistor. The 15k, Zener and current source are internal to the switcher and are shown only to help you understand what's going on.QuoteSee tooki's post above - Reply #26. Most of the ESP32/WS2815B projects I see on the web don't use a level translator.

author: ElecGeek
author_rank: Contributor
timestamp: July 16, 2025, 03:01:38 am
content: Quote from: ledtester on July 16, 2025, 12:58:22 amGot it. I removed Level shifter as well. Here is the final schematic. Sorry for too many mistakes. Its my first PCB.I replaced Xiao ESP32 with cheaper ESP-12F(ESP8266MOD) as I don't need 5V anymore.Let me know if any improvement can be done here. Also, can you please suggest PCB key considerations and component placement.

author: ledtester
author_rank: Super Contributor
timestamp: July 16, 2025, 03:57:33 pm
content: I don't have any more comments but that doesn't mean there aren't more issues.The only other additional advice I have is to follow the recommendations in the TSP562203 datasheet on page 22 for laying out the copper traces around the chip.

author: ElecGeek
author_rank: Contributor
timestamp: July 16, 2025, 05:50:32 pm
content: Quote from: ledtester on July 16, 2025, 03:57:33 pmShall I get all the components and try it on breadboard before ordering PCBs? Is there any emulation that can be run on schematic itself?

author: ledtester
author_rank: Super Contributor
timestamp: July 16, 2025, 06:26:52 pm
content: Yes, it would be a good idea to test the buck converter before ordering PCBs.You can test the TPS chip by using a SMD breakout PCB like what's shown here:https://www.adafruit.com/product/1212or by getting a small copper clad board like these:https://www.amazon.com/uxcell-100x70mm-Double-Sided-Thickness-Prototyping/dp/B07R585RVN/and etching the copper pattern for the chip. Search the web for "diy etching pcb", e.g.:DIY PCB Fabrication (Dry Film Inkjet Method) -- TechBuilderhttps://youtu.be/xyBgbNPrWg8You can also use a knife or dremel to make the copper patterns or suggestions made in this video:Copper Clad Circuit Prototyping Tools -- shabazhttps://youtu.be/jQxTQjB64L0Basically I would become familiar with the chip's operation, make sure the choice of components is adequate for the voltage and current you want to produce.

author: ElecGeek
author_rank: Contributor
timestamp: July 19, 2025, 01:07:32 am
content: Thanks for the detailed information.One more suggestion, which is better, low side switching or high side switching?

author: Kean
author_rank: Unknown
timestamp: July 20, 2025, 03:20:14 pm
content: Quote from: ElecGeek on July 19, 2025, 01:07:32 amI generally only recommend low-side switching for things like relays where there is no other electrical connections sharing the common ground reference. It almost always causes issues if you use low-side switching to a circuit that also has other power or data connections - as you do here with your LED data signal that is referenced to the now disconnected ground.Even with high-side switching you can have problems if you have any other voltages on data lines when power is off. The signal voltage on the data lines can traverse ESD clamping diodes in the ICs to the power rail and lead to all kinds of weird operation, or at least unexpected power draw.

author: ElecGeek
author_rank: Contributor
timestamp: August 06, 2025, 11:40:02 pm
content: Quote from: ledtester on July 16, 2025, 06:26:52 pmIs there any simulation that I can run on this circuit to make sure it works. Custom PCB looks to be a bit difficult. Any other to confirm if it will work fine?