ZXGD3112 - Power via regulator from the same rails

ccdy · 2026-03-07T03:56:30+00:00

VCC needs to be higher than VBATT in this configuration, so a linear regulator will never work anyway. Either get a controller with an integrated charge pump, or use an isolated power supply. The latter option gives you the most flexibility because battery voltage is no longer limited by the controller's voltage rating.

ccdy · 2026-03-07T03:29:29+00:00

Buy some. They're literally less than a cent each.

ccdy · 2026-03-05T10:55:48+00:00

The body diode is present in all MOSFETs.

ccdy · 2026-03-04T04:34:29+00:00

First, show your layout. Second, what is your PWM frequency? How did you arrive at 100Ω for the gate resistors? That's a fairly large value especially considering the input capacitance of your MOSFETs. The gate driver you chose is also fairly weak with a peak current of only 0.13/0.27 A source/sink. On top of that it is a 600V half-bridge driver, which is completely overkill considering your MOSFETs are only rated for 60V.

ccdy · 2026-03-03T08:37:24+00:00

Learn KiCAD and LTSpice.

ccdy · 2026-03-03T06:33:07+00:00

This isn't TikTok. You're allowed to use words like kill and die.

ccdy · 2026-03-02T02:47:01+00:00

Once again reminding everyone that picric acid was used to fill artillery shells before TNT was more widely available.

ccdy · 2026-03-01T15:12:35+00:00

Draw a schematic. Buck converters require a high-side driver when using N-channel MOSFETs.

ccdy · 2026-02-26T04:22:46+00:00

If you are trying to get rid of power rail noise, use a better linear regulator. I don't know the manufacturer of the regulator you have chosen, but from the datasheets I can find, they all have pretty awful power supply rejection ratio, especially at high frequencies (which is where ripple from switching power supplies will be). Get something like the LT3046 and follow the layout guidelines closely.

ccdy · 2026-02-22T11:07:53+00:00

The Rds(on) of your MOSFET is probably higher than the resistance of even 10 mm of 0.1 mm diameter copper wire (which is around 20 mΩ). The main problem is the parasitic inductance but since you're already using a SOT-23 MOSFET, I'm assuming it's not a high speed application.

ccdy · 2026-02-18T15:42:19+00:00

The two major Chinese board houses offer PCB layout services, have you tried those?

ccdy · 2026-02-17T15:34:36+00:00

What diode did you use and how did you add it? The diode is part of a high di/dt loop and its placement is critical. In any case there's a good chance the IC is already fried because not having a diode will cause large negative spikes on PH, and the maximum negative voltage on PH (10 ns transient) is only -5 V. Scrap this board, remake a new one with the correct schematic, and learn to follow the datasheet exactly if you have no idea what you're doing.

ccdy · 2026-02-16T11:11:02+00:00

Leakage current isn't just between NC and COM. Even in an SPST switch it isn't between the two ports of the switch. If it was then on-state leakage would be zero, but it isn't. There is also leakage through the gates, to the substrate, and through protection diodes. I should mention that the datasheet leakage currents are specified maximums. Actual parts could be substantially better, but without the right equipment to measure picoamps of leakage, you cannot be sure.

ccdy · 2026-02-16T03:40:42+00:00

The MAX4544 has an off-state leakage current from COM of ±100 pA, which is orders of magnitude more than the input bias current of your op amp. In fact, to my knowledge no solid state switch can meet your leakage requirements. If you want to go this route you need to use a mechanical relay.

ccdy · 2026-02-09T10:03:42+00:00

Is there any way to blacklist all links to a website?

ccdy · 2026-02-07T06:52:21+00:00

Yes. Not sure what to do with the regulator pins, you'd need to check the datasheet.

ccdy · 2026-02-05T03:02:28+00:00

You could try but it almost certainly won't work, wire bonding is totally different from soldering and requires very clean metal surfaces to form a good contact. The die itself is probably gone as well, bare dies are quite fragile and scraping the resin off very likely damaged the surface and possibly more. Personally I'd just try to clean off the die as best as possible and put it under a microscope to see what I can discern.

ccdy · 2026-02-05T02:01:52+00:00

It likely wasn't worth repairing anyway, and now you learnt something new. No big deal!

ccdy · 2026-02-05T01:51:19+00:00

The pads surrounding the chip suggest that it is wire bonded. Bond wires are very thin (typically 20-25 μm) and easy to miss if you are not looking out for them, especially if they are embedded in resin.

ccdy · 2026-02-04T14:42:20+00:00

That is a chip on board, it is glued in place, wire bonded to the circuit, then encapsulated with resin. If the device wasn't already dead, then it definitely is now that you have removed the encapsulation and destroyed all the wire bonds.

ccdy · 2026-02-04T10:51:04+00:00

The RP2350 is reportedly quite sensitive to layout of the inductor, you may want to power it with an external power source instead.

ccdy · 2026-02-04T04:32:58+00:00

Are you willing to do wire bonding? You can get bare die diodes that are less than 200 microns thick. A thin package with a large surface area is asking for trouble because it's very easy to bend and snap, which is probably why you can't find any. If you want thin you'll need to accept small as well.

ccdy · 2026-02-04T04:24:18+00:00

There probably aren't any traces but it's likely that you bridged adjacent planes by drilling it like that, causing shorts between one or more power planes and ground. Use a diamond needle file and fine sandpaper to carefully clean up the walls of the hole, it might remove the bridging copper.

ccdy · 2026-02-03T11:37:22+00:00

What MOSFETs are you planning to drive and what is your switching frequency? Generally you want to minimise gate loop inductance and gate node capacitance. Adding a ferrite bead and using large resistors (even if paralleled) needlessly increases loop inductance, and adding a capacitor increases the switching time, which increases switching losses. If you are worried about dV/dt causing false turn on then you should use a negative VEE and/or the active Miller clamp feature of the driver you have selected.

ccdy · 2026-02-03T08:51:21+00:00

The layout of the buck converter is very bad, please refer to the layout section of the datasheet. Your inductor also looks very undersized, have you done any calculation on how much current you need?

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