TB6600 Schematic not working!!! please help - Page 1
Forum section: electronics / beginners

author: towfiq55
author_rank: Newbie
timestamp: August 01, 2025, 05:46:18 am
content: Hi everyone,I’m working on a university project involving stepper motor control, and I’ve chosen to use the TB6600 stepper driver for its reliability and ease of use. As part of the project, I’ve designed a custom schematic using the TB6600, but after proceeding with PCB fabrication, it isnt working. the motor is get powered, but not moving.I kept enable and reset pin high with 5V, cause i am not using enable pin to switch on the driver.I’d really appreciate it if someone with more experience could take a look and provide feedback.I’m particularly concerned about whether:My logic level connections are appropriate.I’ve handled the enable/sleep pins correctly.The motor power supply section is adequately protected.Any passive components (e.g., current sense resistors, flyback diodes, etc.) are missing or incorrectly chosen.I’ve attached my schematic below.Could someone please let me know if there are any issues or risks in my design?If anyone has a known-good reference schematic for the TB6600 that I could use for comparison or inspiration, that would also be incredibly helpful.Thanks in advance for your support – I really value the expertise in this forum!Best regards,Towfiq

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 01, 2025, 06:32:18 am
content: not readerble(u**y) schematics. cant understand.

author: towfiq55
author_rank: Newbie
timestamp: August 01, 2025, 06:35:30 am
content: Now I added a Clear image, Is it visible? sorry for the inconvenience.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 01, 2025, 06:48:50 am
content: That's not what I mean. The image is large enough.purpose of the components, and what are their values?The labels overlap and are impossible to read, and the orientation and placement of the power symbols are not based on convention.does not show the direction of current flow and input to output flow (implicitly).I think there is a mistake somewhere, but it's not shows the whole circuits. I have no idea.This way of drawing schematics can cause mistakes (and may already be causing mistakes), and it is impossible to understand when editing later.Would anyone else want to read this? The basics of schematics are to draw them neatly and make them understandable to everyone.First, learn how to draw a correct schematic. you wait, someone will teach you.also, need the images of both sides of the board.Why is the VCC of the TB6600HG connected to Vss?

author: towfiq55
author_rank: Newbie
timestamp: August 01, 2025, 07:20:35 am
content: Hi, Thank you for your time and welcoming me. Sorry for the compact desgin, actually i was designing a PCB with arduino uno and 2 TB6600 motor driver, so I just gave one part schematic , cause i tested the arduino was working fine.I am attaching another image which can visualize clearly . I marked in schematic:1. main voltage source 24VDC.2. Header connectors for step and direction, and output pins for bipoler stepper motor3. The 74HC14 is used for signal conditioning, noise filtering, debouncing, and pulse shaping before the signal is sent to the stepper driver. (so far I learnt from online)4. 6N137 to provide optical isolation between the microcontroller and driver5. Setting the Vref to fixing maximum current flowand unmark area is the motor driver chip.Hope its more clear now. Thank you again.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 03, 2025, 03:48:44 am
content: TB6600 is not a very good IC, nor very reliable as far as I know. Or at least not the chinese versions / clones. I've bought a few of the cheap boards with aluminimum heat sink, and on several the current select witches were broken on arrival. That does not say anything on the IC itself of course, but once I had it going, the motors were quite noisy and did not run smooth. Some of the microstepping settings were worse then what you'd expect from the settings.For your schematic... I looked at it for about 10 seconds. I really dislike schematics where pins are drawn in "IC order", instead of logical groups, so that is where I stopped.

author: amyk
author_rank: Super Contributor
timestamp: August 03, 2025, 07:27:32 am
content: That's not a schematic, it's a "pile of parts flying in loose formation."The whole point of wires is to show what's connected to what. Searching for net names (in an image!) defeats the purpose of a schematic.

author: Sauli
author_rank: Contributor
timestamp: August 03, 2025, 07:41:49 am
content: -The connector for the Step and Dir signals does not have a return (ground) path. Is there one somewhere else? Where do these signals come from?-Vreg is an output and must not be connected to +5V.-RESET and ENABLE should be low when power (Vs) is applied to the stepper driver. Are they?-M1, M2 and M3 must not be all high or all low.-U12 serves no purpose as far as I can see. TQ should not be controlled by the Step pulse. LED3 works similarly to LED4: always on when there is +5V available.-The motor won't run when ALERT is active (LED5 is on). I would connect LTC permanently high to automatically recover from thermal shutdown.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 03, 2025, 09:26:20 am
content: Beginners tend to want to use labels. I don't understand why.

author: SteveThackery
author_rank: Super Contributor
timestamp: August 03, 2025, 09:33:21 am
content: @towfiq55: the way you have drawn the schematic works fine for KiCAD or whatever PCB design software you are using. However, it is EXTREMELY difficult for a human to interpret because you are using labels to connect things together rather than wires. Therefore the viewer must try to hold all the many connections in their head when trying to visualise how the circuit functions. Also, if there are several connections with the same label, the viewer must search across the whole circuit to make sure they haven't missed one.It is FAR better to draw the circuit using wires for the interconnections, and to follow the general rule: signal flows from left to right, power flows from top to bottom. It's all the same to your PCB design software, but it makes it so much easier for you and others to "read" the schematic.I do think there is a case to be made for putting the power supply components in a separate box, but that's all.Right now your schematic is a right old mess, with cramped up and overlapping labels, no apparent logic to the structure, ground and power symbols in all directions. Frankly, I find it just too hard to bother trying.Forgive me if I sound harsh. I'm only saying this because it makes it harder for people to help you.

author: towfiq55
author_rank: Newbie
timestamp: August 04, 2025, 12:52:46 am
content: Thank you @SteveThackery for your useful suggestion, I really appreciate your recommendation.

author: towfiq55
author_rank: Newbie
timestamp: August 04, 2025, 01:06:29 am
content: Thanks Sauli for reply,1. Yes, step and direction pin has return ground2. Vreg is an output pin, i connected to 5V , cause it has a inbuilt regulator in chip which provide the logic voltage for step and dir pins, and i am giving switching instruction from microcontroller to allow that 5V for step and dir pulse. I didnt connect any external 5v in that pin, (my external source signal name Vcc = 5v, Vss=24v)3. no, RESET and ENABLE was not low when power (Vs) is applied to the stepper driver. But I tried by keeping them low by connecting pins with a jumper wire from ground pin, still wasnt working.4. M1 is high, M2 and M3 are low.

author: towfiq55
author_rank: Newbie
timestamp: August 04, 2025, 01:10:45 am
content: Hi Doctorandus_P, Thank for your reply, do you have any recommendation for a good ic, which can offer 24V and 4.2 Imax for nema 23? I found TB67S581FNG on pololu, but confused if i need large heatsink for operating that in such high current. and that one pretty expensive as well.

author: PGPG
author_rank: Frequent Contributor
timestamp: August 04, 2025, 09:23:39 am
content: Quote from: towfiq55 on August 01, 2025, 07:20:35 amTransoptors allow to communicate between devices working at different GND potentials (depending on type they can accept even several kV voltage difference).If you connect transoptor LED side and output side to the same GND than you not use its isolation properties.The only you get is delay in signal and may be some level shift or logic negation.

author: Sauli
author_rank: Contributor
timestamp: August 04, 2025, 12:55:43 pm
content: QuoteYour schematic shows +5V is used for a lot more than just logic voltage for Step_pin and Dir_pin. The TB6600HG datasheet does not give the maximum load current for Vreg, but it does say that you can use it for ALERT and MO pullup resistors with 1mA max each. LED3 and LED4 alone use a lot more and if ALERT goes active, LED5 is also fed by +5V.My advice is to check all the pins of the driver chip with an oscilloscope to see if the voltages are what they should be. Don't create any shorts while doing thatAnd of course you have checked the Vref voltage? The motor won't run if it is too low.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 04, 2025, 01:49:12 pm
content: Quote from: towfiq55 on August 04, 2025, 01:06:29 amUsing Vss as a symbol for positive voltage is completelyridiculous.It will inevitably lead to misunderstandings.VDD, VCC, GND, EARTH, VEE, and VSS all have clear meanings and should be distinguished from each other, but let's leave the difficult stuff aside for now.Use VCC (VDD) for positive voltage, GND for ground, and VSS for negative voltage.when multiple voltage domain exist within a circuit, to prevent misunderstandings, specify a specific voltage as a symbol.if the same voltage is used in different domains, add an underscore to the name.+3V3, +5V0, +3V3_LVLOGIC, +5V0_HVLOGIC

author: TimFox
author_rank: Super Contributor
timestamp: August 04, 2025, 03:55:20 pm
content: Quote from: squadchannel on August 04, 2025, 01:49:12 pmVdd is the voltage supply for drains (which is positive for NMOS).Vcc is the voltage supply for collectors (which is positive for NPN)Vee is the voltage supply for emitters (which is negative for NPN)Vss is the voltage supply for sources (which is negative for NMOS)This is ambiguous when NPN and PNP are mixed, etc.Vbb is the voltage supply for vacuum-tube plates (which is always positive)Tags +5V0, etc. are unambiguous.