Diodes, Inc

It avalanches but they don't specify the voltage!

torsdag den 20. juli 2023 kl. 16.44.27 UTC+2 skrev John Larkin:

the drain-gate zener makes it shunt so one would assume it does that at ~60V and avalanche never happens

torsdag den 20. juli 2023 kl. 16.29.37 UTC+2 skrev John Larkin:

I am now using a 250W 12V to 24V inverter to activate 4 relays.

Abs max is 60 volts, without a clue what that zener clamps at.

Same as avalanche-rated fets, no hint of the actual clamp voltage. Grrrr.

torsdag den 20. juli 2023 kl. 19.51.24 UTC+2 skrev John Larkin:

Aussitôt dit, aussitôt fait.

I measured this on a clunky ERNI REL20 relay from my junk box. When the armature moves, the coil current actually briefly drops. See

Jeroen Belleman

Lots of words, no numbers.

torsdag den 20. juli 2023 kl. 22.57.57 UTC+2 skrev John Larkin:

atleast 60 and less than the mosfets avalance voltage ..

which is never even hinted it.

I buy parts and test them. Sometimes that's really interesting. Some parts are fine at 5x abs max voltage, some blow up at 10% over.

fredag den 21. juli 2023 kl. 13.49.55 UTC+2 skrev John Larkin:

"The back‐to‐back Zener stack, shown in figure 2, between the MOSFET’s gate and drain connections, is the key component in this low‐side, active clamp configuration. The clamp voltage is set by the Zener stack voltage and is designed to be less than the avalanche breakdown voltage of the MOSFET’s drain to source junction but high enough not to be triggered in normal operation."

and sometimes the damage doesn't show up until later, it all depends on what you are doing

I would not rely on internal zeners. I have 2x 13V 10W zeners on my 24V relay driver. Probably overkill, but zeners are cheap.

Why isn't that voltage on the data sheet?

I tested a bunch of polymer electrolytics at reverse voltage for over a month. That's not specified. Leakage current very gradually declined, so they looked OK for production.

fredag den 21. juli 2023 kl. 17.56.49 UTC+2 skrev John Larkin:

No. It doesn't zener at 60. What would the flyback voltage actually be? It might be sorta guessed from the abs max flyback energy, but I'd like to know the decay time when driving a relay. All the curves, including SOAR, end at 60 volts.

The pattern I've seen in discretes is breakdown voltages between 1.5 and 2.0 x specified abs max. Most go into soft conduction (like the EPC GaN parts) and some fail and die hard, even current limited.

I want to know that.

I've seen some ICs, like LM1117, that work at 5x rated abs max. One opamp wasn't even reliable at abs max.

What makes them dynamite as compared to, say, TPS564201? Looks like a boring synchronous buck. What do I miss?

Best regards, Piotr

maybe not much, but the AP66200 can take 60v input

I love those little TI switchers. We use tons of them. But the best they can do on input voltage is 28, and their current rating is optimistic, in my opinion.

I have 48 volts and need to make 12 to power a brickwall of relays. HV-input switchers are rare. I'd use the trusty old LM2576HV but I don't have room for it and its giant catch diode and inductor and caps. It switches at 50 KHz!

Pulse skip mode is fine for powering relays but can cause problems in analog circuits, so we prefer to stock parts that don't do that. The TIs do have spread-spectrum, which is cool for EMI tests and somehow doesn't seem to get into the DC output. Clever.

SRH05 is a very cool part, but only good for 500 mA out. I guess I could use four of them.

(Being a Red-Blooded Real American, I say "the future.")

OK, that's something! Some of the TI parts can take 38V at most.

Best regards, Piotr