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The RF Workbench / Re: Class D audio amps - protection circuits
« on: May 04, 2023, 1827 UTC »
Yep, agree these ICs are based on a common die with metal and bond-out/package options. Defeatured parts like the 3111 go into the 28 pin package, actual 3116/8 parts are 32 pins. So while it's true that if you have a part branded 3118 in a 28 pin package, it's a fake. Having a 32 pint part doesn't guarantee that it's genuine but the one I've had in a transmitter for a couple of years looks genuine and I've never had any of these problems with it.
In fact I wonder if metalization options may even determine the power rating, based on the number of output FETs that are actually connected. Also how many of these rebranded 3111 parts are final test failures? I say that because I've now broken at least four of them. Three were the kind with screw terminals which came with PLIMIT configured to limit the output voltage to 1/2 of PVCC. After changing them to allow full voltage swing, all have died with the outputs at full PVCC rather than half. That indicated a shorted high side FET, even though the 3111 is rated to 26V just as the 31118 is (and they did work, for a while at least). Speculate they may have been test failures that were sold with the stipulation that the output had to be derated (as a former test engineering manager I well know the manufacturing mantra that there's a buyer for everything..at the right price).
The biggest culprit here is me - as I didn't follow my elementary school teachers advice about paying attention. If I had been I'd have known the 28 pin amplifiers could not be true 3116/8 parts despite what the friendly eBay seller claims. A bag of 10 more showed up yesterday, so I've got plenty of LM-386 replacements now :-)
I'd started laying out a PCB to make my own, but it seems there may be some reliable suppliers of genuine TI 3189 parts, which is all I am after (although the ability to control power-up sequencing and integrate the modulator with the RF section would be pluses). I also have one of what I think are referred to a the "Drok amp" which has the onboard boost converter to make it's own 24V, which has worked well, but seems to be hard to find. The actual board is marked with the name "Shareelec" and that comes up in search as CIRMECH: https://shareelec.aliexpress.com/store/1101230787
One part on this page is a $4.50 board that claims to have a TPA3116D2 although it's hidden by the heatsink - has anyone used any of the CIRMECH amps?
A company with a range of products like this seems to be a cut above the bargain-basement eBay sellers of products they don't understand or have any control over. I'll be buying and trying more of these amps as modulators but lesson learned - only 32 pin parts!
Any sources of the Drok-type class D BTL amplfiers with the built-in boost converter? I think they were sold as "bass amplifiers".
Bob
In fact I wonder if metalization options may even determine the power rating, based on the number of output FETs that are actually connected. Also how many of these rebranded 3111 parts are final test failures? I say that because I've now broken at least four of them. Three were the kind with screw terminals which came with PLIMIT configured to limit the output voltage to 1/2 of PVCC. After changing them to allow full voltage swing, all have died with the outputs at full PVCC rather than half. That indicated a shorted high side FET, even though the 3111 is rated to 26V just as the 31118 is (and they did work, for a while at least). Speculate they may have been test failures that were sold with the stipulation that the output had to be derated (as a former test engineering manager I well know the manufacturing mantra that there's a buyer for everything..at the right price).
The biggest culprit here is me - as I didn't follow my elementary school teachers advice about paying attention. If I had been I'd have known the 28 pin amplifiers could not be true 3116/8 parts despite what the friendly eBay seller claims. A bag of 10 more showed up yesterday, so I've got plenty of LM-386 replacements now :-)
I'd started laying out a PCB to make my own, but it seems there may be some reliable suppliers of genuine TI 3189 parts, which is all I am after (although the ability to control power-up sequencing and integrate the modulator with the RF section would be pluses). I also have one of what I think are referred to a the "Drok amp" which has the onboard boost converter to make it's own 24V, which has worked well, but seems to be hard to find. The actual board is marked with the name "Shareelec" and that comes up in search as CIRMECH: https://shareelec.aliexpress.com/store/1101230787
One part on this page is a $4.50 board that claims to have a TPA3116D2 although it's hidden by the heatsink - has anyone used any of the CIRMECH amps?
A company with a range of products like this seems to be a cut above the bargain-basement eBay sellers of products they don't understand or have any control over. I'll be buying and trying more of these amps as modulators but lesson learned - only 32 pin parts!
Any sources of the Drok-type class D BTL amplfiers with the built-in boost converter? I think they were sold as "bass amplifiers".
Bob