I just can’t trust Tantalum cap. It’s so delicate. For safety’s sake, it’s recommanded to use under 1/3 rated voltage and it can’t handle high dv/dt.
What’s worse it may explode and catch naked fire while over voltage. E-cap just leak or puff.
I guess E-cap plus MLCC is the best choice.
That’s a good discussion, and very educational.
This used to be true for the old technology tantalum capacitors. The new ones are getting a lot better.
The KEMET Organic Capacitor (KO-CAP) is a tantalum capacitor with a Ta anode and Ta2O5 dielectric. A conductive organic polymer replaces the traditionally used MnO2 as the cathode plate of the capacitor. This results in very low ESR and improved capacitance retention at high frequency. The KO-CAP also exhibits a benign failure mode which eliminates the ignition failures that can occur in standard MnO2 tantalum types. KO-CAPs may also be operated at voltages up to 90% of rated voltage for part types with rated voltages of ≤10 volts and up to 80% of rated voltage for part types >10 volts with equivalent or better reliability than traditional MnO2 tantalum capacitors operated at 50% of rated voltage.
The above is from way back in 2012 I believe.
Source:
https://sh.kemet.com/KO-Conductive-Polymer
However, you have a point. In an amateur circuit, with no protection, they may not be worth the risk. As usual, caveat emptor.
Tan-cap is good in density. Seeking for best performance, solid electrochemical capacitors might be better.
I did some searching and thats interesting.
100 uf 20v High Voltage Polymer:$0.5, 55mOhm, 2A max ripple current.
In the meanwhile, 100uf 35v solid electrochemical capacitors: $0.13, 23mOhm, 2.8A max ripple current.
Looks really good! how is this project going? I would love to buy one for testing 
Welcome. Hope all is well and you find what you need here.
It’s going well, thank you. The board is fine, it needs some fine tuning, but otherwise is all right. So far it hasn’t blown up or smoked or anything.
Not sure how we could do that, as I don’t really sell those. Please PD/DM me on the board, we may be able to arrange some one-off deal if you really need this.
Cheers,
Valentine
Dear Valentine, how is this project going? it sounds very interesting. is it open source? i will be a treat to learn from because it sounds like it’s not just an educational project but something that is production grade.
Hi,
Thank you for sharing this information.
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I believe I posted the schematics under open hardware share.
The link is at the beginning of the thread.
Cheers,
Valentine
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Yes, sure, Welcome.
Cheers,
Valentine
Hi Valentine, is it still available?
Thanks!
Yes but I took the schematics down.
Also these mosfets are not really good either.
Cheers,
Valentine
I noticed this comment regarding these devices. I have also tried the oldest and worst in this family called BTS7960, and it comes on a very cheap H-bridge board on the market called IBT_2. An important notice is, that they have an input to control their slew rate by applying a resistor, Rsr to ground. This is a comparison derived from the datasheets:
According to the datasheets, the IFX007T should be better than the BTN8982. And the switching losses should typically be about 10 times better than the BTS7960. It is pin-compatible devices.
The IBT_2 board have been reviewed and I have commented on it as well in this Arduino forum:
https://forum.arduino.cc/t/bts7960-btn7960n-ibt-2-motor-drive-module/1142926/5
I think the IFX007T should be fair to use in an H-bridge (two half bridges) for use with brushed DC motors or with large stepper motors, and with a PWM frequency at motor of 20 kHz. They got current sense, and it improves their performance for fast control loops, because you are able to measure the signed DC motor current. The devices got some protective measures if the supply voltages exceed 27VDC. If you use active breaking, you need to apply sensitive over voltage protection, if used with 24 VDC.
The IBT_2 boards are often sold for about 3 euro, and they have got a fair heat sink. I got at plan to try to replace the BTS7960 with IFX007T on such a board to find out about the performance. I estimate that they should be able to handle a DC motor current continuously of about 12 A and with four quadrant fast servo control. Even though this forum are for BLDC motors, I like to say, that brushed DC motors are still a cheaper alternative for many applications. But I also think BLDC motors are taking more and more market shares.
I do NOT think these devices are applicable for BLDC motors with use of current vectoring control and use of these current sensors. You cannot measure negative currents in the upper transistors with the sensors in the upper transistors. Therefore in about half the cases, you cannot calculate the correct current vector in the motor. You may of cause then add in line current sensors to compensate for that, but then I think other solutions will be more preferable anyway.
In my experience anything over 10k on these is dangerously close to overheating to a point no heatsink can remove the heat fast enough, you hit the casing thermal limit. I mean they are OK for DIY but anything serious you need discrete components or really carefully calibrate your use case.
However they fill a very important niche of high voltage, high current, high integration (low implementation complexity) and low cost. Unbeatable, especially for intermittent motor power at steady state.
Cheers,
Valentine
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When you drive an H-bridge for a DC-motor the “right” way, each half bridge is switched at 10 kHz, and it causes the motor to see a PWM frequency of 20 kHz. Look the link to the Arduino forum above for details. However, I start to get the impression, that most users use the next best way to drive an H-bridge for a DC-motor, with only one half-bridge active most of the time.
I have not analyzed the frequencies a BLDC motor will see, when each of the three half-bridges are given a 10 kHz PWM frequency.
The link above do provide my conclusions regarding temperature, with the use of two BTS7960 for an H-bridge. I think it should manage a motor current of about 6 A at 20 kHz motor PWM frequency and with 24 VDC supply to the H-bridge. I have not tried the IFX007 yet, but according to the data sheets, it should have about 9 times less switching losses.
So it seems, that we have got different experiences here.